Next Article in Journal
Comparative Transcriptome Analysis Reveals the Effects of a High-Protein Diet on Silkworm Midgut
Previous Article in Journal
The Delineation of Management Zones of the Halyomorpha halys (Hemiptera: Pentatomidae) Population Based on Its Spatiotemporal Distribution for Precision Agriculture Purposes
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Insects
Volume 16
Issue 4
10.3390/insects16040338
insects-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Phototaxis Characteristics of Lymantria xylina (Lepidoptera: Erebidae)

by
Jifeng Zhang
1,
Baode Wang
2,*,
Rong Wang
1,
Xiancheng Peng
1,
Junnan Li
3,
Changchun Xu
4,
Yonghong Cui
1,
Mengxia Liu
1 and
Feiping Zhang
1,*
1
Forestry College, Fujian Agriculture and Forestry University, Fuzhou 350002, China
2
US Department of Agriculture, Animal and Plant Health Inspection Service, S&T, Forest Pest Methods Laboratory, Buzzards Bay, MA 02542, USA
3
Fujian Academy of Forestry Sciences, Fuzhou 350012, China
4
Zhejiang LOIHOI Agriculture and Forestry Technology Co., Ltd., Taizhou 318058, China
*
Authors to whom correspondence should be addressed.
Insects 2025, 16(4), 338; https://doi.org/10.3390/insects16040338
Submission received: 12 February 2025 / Revised: 13 March 2025 / Accepted: 22 March 2025 / Published: 24 March 2025
(This article belongs to the Section Insect Behavior and Pathology)
Browse Figures
Review Reports Versions Notes

Simple Summary

Lymantria xylina Swinhoe (Lepidoptera: Erebidae), a significant forestry pest in southeastern coastal areas of China, is a regulated invasive insect in some countries. Evidence suggests that L. xylina females exhibit phototaxis and possess certain flight abilities, raising concerns about their potential to be attracted to and fly to vessels docked at ports, and egg masses or adults have been intercepted on freighters arriving at a few seaports in the United States and Korea. However, the specific phototactic characteristics and sensitive wavelengths of L. xylina remain unclear. To address this knowledge gap, we conducted a comprehensive study on the phototaxis of L. xylina adults. We employed different wavelengths and powers of insecticidal lamps to trap adults in the field and tested their phototactic response in various reproductive states in a darkroom. By combining these field and laboratory experiments with data on the weight and egg-carrying capacity of light-trapped female moths, we aim to elucidate the phototaxis characteristics and dispersal ability of L. xylina. This research will add more information for evaluating the risk of L. xylina reaching vessels through phototaxis flight and spreading long distances via ocean-going vessels.

Abstract

Lymantria xylina Swinhoe (Lepidoptera: Erebidae) is considered a potentially internationally invasive forest pest with limited knowledge about its phototactic behavior. This study investigated the phototaxis of L. xylina males and females using various insecticidal lamps in the field. The results showed that all lamps attracted both males and females, but females were captured in a very low numbers, with a female-to-male ratio of 1:322. The insecticidal lamp with a peak wavelength of 363 nm was most effective for male trapping. Males exhibited a distinct light-trapping rhythm, peaking around midnight (23:00–0:00), with 29.5% capture, while females were most active at dusk (19:00–20:00), with 44.4% capture. Light-trapped females were smaller and lighter than indoor-emerged females and had lower egg-carrying capacity. Females, when laying eggs, did not exhibit phototactic behavior. Only 14.6% of non-ovipositing females showed phototactic behavior, and only 0.6% flew directly toward the lamp. These findings suggest that while non-ovipositing females can exhibit phototaxis, only a small proportion will, potentially reducing the risk of long-distance dispersal of L. xylina via ocean-going freighters. The results showed that the non-ovipositing females could fly under phototaxis, but their phototaxis was limited. This study provides a basis for the risk assessment of the long-distance dispersal of L. xylina via ocean-going freighters through female moth phototactic flight.

1. Introduction

Phototaxis, a fundamental behavioral response to light stimuli by most insects, plays a pivotal role in insect behavior, influencing navigation, host and food finding, dispersal, mating, and predator avoidance [1,2,3]. Positive phototaxis is exploited in light trapping, a key tool in Integrated Pest Management (IPM) and has become an important monitoring and pest control tool. By attracting and capturing insects, light traps offer several advantages, including delaying pesticide resistance, reducing control costs, and minimizing environmental impacts [4,5].
Lymantria xylina Swinhoe, commonly known as the casuarina moth, is a lepidopteran pest of the family Erebidae. It is also known as the casuarina tussock moth, xylina tussock moth, acacia tussock moth, and dark-margined tussock moth [6,7,8,9]. Adult L. xylina exhibits typical sexual dimorphism, with apparent differences in the morphology, body weight, and potential flight ability between male and female moths [10,11,12]. It is primarily distributed in Japan (Kyushu and Okinawa, Japan), India, and regions of China, such as Fujian, Taiwan, Guangxi, Guangdong, and Zhejiang. Its extensive host plants pose significant potential risks, as it can damage 424 plant species and shrubs across 103 families (3 subfamilies), including 58 economic crops. In regions like Fujian and Taiwan, L. xylina is one of the primary pests of Casuarina equisetifolia Forst and Acacia confusa Merr; it hinders the normal growth of trees, accelerates the weakness of trees, and even causes the death of whole trees [10,13]. In Fujian, China, L. xylina adults generally begin to emerge at the end of May, show peak emergence in early June, and end in late June [14]. In Fuzhou in 2017, the emergence period lasted about 35 days, with the initial period from 23 May to 30 May, the peak period occurring from approximately 8 June to 12 June, and the final period from 19 June to 27 June [12].
Due to its taxonomic relationship with the Asian subspecies of Lymantria dispar Linnaeus and similar biological characteristics, L. xylina is considered a major invasive pest, gaining international attention and being considered to pose a potential risk of biological invasion [15,16]. Both male and female L. xylina exhibit phototactic behavior, with males capable of long flight and some females capable of shorter flight. Females may be attracted to ships’ lights and subsequently land on ships or cargo to lay eggs, resulting in long-distance movement to a suitable habitat with the cargo or ship [12,17]. Studies have shown that L. xylina may have a severe invasion risk to subtropical areas in the United States, such as Hawaii, Florida, and Southern California [18,19]. While female L. dispar dispar is typically flightless, L. xylina females have the potential for limited flight, suggesting a greater dispersal capacity than that of L. dispar dispar [10,20,21,22]. Since 2014, several interceptions of L. xylina adults and egg masses have been found on ships in some ports in Korea, and egg masses have also been found on vessels called at the U.S. ports [12,23,24,25], further highlighting the risk of long-distance dispersal via maritime transport. However, the extent of phototactic behavior in female L. xylina remains unclear, particularly for the population in mainland China, where no reports of light trapping or phototactic flight behavior in females exist.
The movement of L. xylina egg masses via sea transportation poses a significant risk for long-distance dispersal. Female moths, attracted to light sources, may lay eggs on ships or cargo at ports or containers stored at ports [10,17]. While the phototactic behavior of L. xylina adults, especially female moths, is crucial to understanding this risk, limited research exists. Studies in Lychee orchards in Taiwan have shown that high-pressure mercury lamps can effectively trap both L. xylina male and female moths with peak activity occurring between 19:00 and 19:30 [26]. In the coastal areas of mainland China, a large number of L. xylina adults can also be attracted using frequency–vibration insecticidal lamps [27]. However, the specific wavelength preferences of L. xylina and the complete light-trapping rhythm remain unknown.
Insect compound eyes typically have three types of photoreceptors, with the most sensitive in the ultraviolet A region (315–400 nm), being generally concentrated around 365 nm [3,28]. Based on previous studies on the field light trapping of L. dispar asiatica, females are more sensitive to wavelengths of 365 nm and 380 nm [29]. To investigate the phototaxis of L. xylina and its potential for long-distance dispersal, this study examines the response of moths to insecticidal lamps with five different peak wavelengths—363 nm, 365 nm, 368 nm, 378 nm, and 439 nm—in a Casuarina plantation. The phototactic behavior of L. xylina adults with different reproductive states was tested indoors. By understanding the factors influencing female moth flight and attraction to light, we can better assess the risk of long-distance dispersal of L. xylina via ocean-going freighters and develop effective risk mitigation strategies.

2. Materials and Methods

2.1. Experimental Site

The main experimental site (Figure S1, see Supplementary Materials) was located in Pingtan County, Fuzhou City, Fujian Province, China (119°42′48.05″ E, 25°31′51.71″ N), with an elevation of 7.2 m. It is characterized by a subtropical monsoon climate and flat terrain, making it one of the three major wind channels in Pingtan, where wind speeds can reach 14.6 m/s (level 7) at night. The land has undergone sand-fixation afforestation and is predominantly composed of a monoculture of artificially planted Casuarina trees, covering an area of 1333.3 hm2. The average tree height and diameter at breast height (DBH) of Casuarina trees at this location were 7.93 m and 8.67 cm, respectively [30].

2.2. Experimental Materials

Since fluorescent lamps were one of the primary light sources for insecticidal lamps and ship lighting, the light source for insecticidal lamps was chosen to be fluorescent lamps, provided by Shenzhen Guanhongya Optoelectronic Technology Co., Ltd., Shenzhen, China, and Zhejiang LOIHOI Agricultural and Forestry Technology Co., Ltd., Taizhou, China. The wavelengths of the light sources were identified by the Physics Laboratory of the Physics Experimental Teaching Demonstration Center of Fujian Agriculture and Forestry University, Fuzhou, Fujian, China (Table 1).
The electric insecticidal parts were manufactured by LOIHOI (Figure S2). The direct current power supply was a 12 V, 20 Ah battery (6-DZF-20, Tianneng Battery Group Co., Ltd., Huzhou, China), and an alternating current was provided by a battery and inverter (NB500, Beijing Newmine Technology Company, Beijing, China). These electric insecticidal parts were equipped with a 4000 V circular high-voltage grid to electrocute the attracted pests, causing them to fall into a collection box, thus controlling and killing them.

2.3. Experimental Methods

2.3.1. Trapping Effects of Insecticidal Lamps with Different Wavelengths

Adults of L. xylina were trapped during the late peak (26–28 June and 3–5 July 2018) and peak (4–6 June 2019) period of emergence [12,14,27]. Five types of insecticidal lamps (L360, L365, L370, L380, and L405) were used, one for each lamp. The insecticidal lamps were randomly placed daily, with a hanging height of 2 m and about 50 m apart. The insecticidal lamps were turned on at 19:00 every night and off at 4:00 the next day. The number of male and female moths trapped by each lamp was recorded hourly (across nine time periods).

2.3.2. Trapping Effects of L360 Insecticidal Lamps with Different Powers

Because the L360 insecticidal lamp had the best trapping effects on male moths in 2018, the L360 insecticidal lamps with different powers (15 W, 25 W, and 35 W) was used for trapping at the peak period (5–7 June) and late peak period of emergence (15–17 June) in 2019. One lamp for each type was used, and the same method was followed as in Section 2.3.1. The daily trapping of each lamp was counted.

2.3.3. Weight and Egg-Carrying Capacity Between Light-Trapped and Indoor-Emerged Adults

In 2019, a total of 26 female L. xylina were trapped using insecticidal lamps in the forest (Table S1), and 30 trapped male moths were randomly selected. Moreover, these adults were marked as the light-trapped group (outside). A total of 30 male and 30 non-ovipositing female indoor-emerged moths were randomly selected as the indoor-emerged group (inside), and their pupae were randomly collected from the forest, the same as the light-trapped group. After weighing the adults, each female moth was dissected, and the total number of eggs was counted to determine their egg-carrying capacity.

2.3.4. Observation of Phototaxis Behavior Indoor

From May 28 to 31, 2021, the tests were conducted in a dark room measuring 7.2 m × 6 m × 3 m using an L360 insecticidal lamp (25 W) as the light source, which was placed on one side of the room (Figure S3). The non-ovipositing adults emerged from the pupae collected in the field, and the egg-laying female moths with the attached Casuarina twigs were collected from the same field. The collection sites were the same as in Section 2.1. Net cages containing L. xylina adults were placed 7.0 m from the light source. The light source was turned on from 21:00 until 4:00, and the movement of male and female moths toward the light source was continuously observed. This study was conducted three times: Test 1 involved 44 males and 43 females (1–3 days old, unmated, not laid eggs), Test 2 involved 89 males and 78 females (1–3 days old, mating status unknown, not laid eggs), and Test 3 involved 30 egg-laying females.

2.4. Data Analysis

The daily trapping number was normalized using the formula Zij = yij/mi × 100% to minimize the effects of random variations on the test results, where Zij represents the adjusted daily trapping number for each type of insecticide lamp, yij represents the daily trapping number for each type of insecticide lamp, mi represents the total daily trapping for all insecticide lamps, i represents the date, and j represents the lamp number.
After calculating the values of Zij, the variance was analyzed using SPSS 22.0 software (IBM, Armonk, NM, USA). Duncan’s test was used to make multiple comparisons. The independent sample t-test was used to compare the two groups. Linear regression was performed using the Levenberg–Marquardt method.

3. Results

3.1. Trap Catches of Insecticidal Lamps with Different Wavelengths

3.1.1. Comparison of The Trapping Effects of Insecticidal Lamps with Different Wavelengths on Male and Female L. xylina

During the late peak period of emergence, all five insecticidal lamps caught male moths of L. xylina, while no female moths were caught (Table 2 and Table S2). During the peak emergence period (4–6 June 2019), a total of 2911 L. xylina adults were caught using five types of insecticidal lamps—2902 males and 9 females—resulting in a female-to-male ratio of 1:322 (Table 2 and Table S1). A substantial number of male moths were caught using all five insecticidal lamps. The L360 lamp exhibited the highest capture rates for male moths, with the maximum total of 1046 and maximum daily catches of 773 moths (Figure S4). In contrast, female moth captures were minimal across all five lamp types. The maximum total number of females captured using any single lamp was only three (L370), and the maximum daily trapping number was two individuals (L370 and L405). The disparity between male and female captures was significant for each lamp type. The maximum total and daily female-to-male ratios of each insecticidal lamp were 1:168 and 1:62 (L405), respectively. These findings suggest that while the L. xylina female exhibits some degree of flight phototaxis in the wild, this behavior is considerably weaker than that of male moths.
The adjusted daily capture rates of male moths using different insecticidal lamps are shown in Figure 1a,b. All lamps captured a substantial number of male moths. The L360 insecticidal lamp demonstrated the highest capture rate, followed by the L370 and L365 lamps. During the peak period of emergence, no significant difference was observed in the number of male moths captured using the different lamps (F = 2.593, df = 4, p = 0.101) (Figure 1a). However, during the late peak period of emergence, the number of male moths captured using the different lamps was significantly different (F = 5.367, df = 4, p = 0.007) (Figure 1b). Notably, the L360 lamp accounted for 31.0% and 39.5% of the total male moth captures during the peak and late peak periods, respectively.

3.1.2. Light-Trapping Rhythm of Male and Female L. xylina

Due to insufficient female moth captures by individual insecticidal lamp types, data from all five lamp types were combined to assess female light-trapping rhythm. Table 3 presents the capture numbers of male and female L. xylina during the different time periods at the peak period of emergence (F = 3.156, df = 8, p = 0.020). The number of female moths captured during the period 19:00–20:00 was the highest, accounting for 44.4% of the total female captures, followed by the 20:00–21:00 period. Subsequently, female captures declined significantly, with no female moths trapped after 23:00. These findings suggest that female moths exhibit peak sensitivity to these lamps shortly after dusk (19:00–20:00).
Significant differences were observed in the number of male moths captured across different time periods (F = 3.156, df = 8, p = 0.020). The highest capture rate for male moths occurred between 23:00 and 0:00, accounting for 29.5% of the total male captures, followed by the 22:00–23:00, 0:00–1:00, and 21:00–22:00. These results show that the male moths exhibit peak sensitivity to these light sources around midnight.

3.2. Comparison of Trapping Effects of L360 Insecticidal Lamps with Different Powers

Capture rates were comparable for the L360 lamps with 15 W and 25 W, while the 35 W lamp caught the least (Figure 2a,b). No significant difference in male moth captures was observed among the different power levels for the L360 lamps during the peak period of emergence (F = 0.924, df = 2, p = 0.447) (Figure 2a). However, during the late peak period of emergence, a significant difference (F = 19.922, df = 2, p = 0.002) was found in male moths captures using L360 lamps with different power levels (Figure 2b). Notably, the 25 W lamp captured no female moths, while the 15 W and 35 W lamps captured only one female moth during the peak period of emergence.

3.3. Comparison of Weight and Egg-Carrying Capacity Between Light-Trapped and Indoor-Emerged Adults

The average weight of indoor-emerged female moths (1.03 ± 0.06 g) and light-trapped female moths (0.75 ± 0.05 g) was higher than that of male moths (indoor-emerged group: 0.21 ± 0.05 g; light-trapped group: 0.12 ± 0.02 g) (Figure 3a). In the same sex, there was a significant difference in weight between the indoor-emerged group and light-trapped group (female moth: F = 2.379, df = 54, p = 0.0003; male moth: F = 9.428, df = 58, p < 0.001).
Light-trapped females (383.8 ± 32.3 eggs) exhibited significantly lower egg-carrying capacity compared to indoor-emerged females (685.2 ± 42.4 eggs), with the latter being 1.79 times greater (F = 5.312, df = 54, p < 0.001) (Figure 3b).
A strong linear correlation was observed between the weight and egg-carrying capacity in both groups (indoor-emerged females: r2 = 0.941, p < 0.001; light-trapped females: r2 = 0.903, p < 0.001). However, the linear slopes indicated a lower egg-carrying capacity for light-trapped females compared to indoor-emerged females at equivalent weights (Figure 3c).
In general, compared with the indoor-emerged female moths, the light-trapped female moths were lighter in weight and lower in egg-carrying capacity.

3.4. Phototactic Behavior of L. xylina Adults Indoors

In Test 1, 14 out of 44 male moths flew directly toward the lamp, while 13 males exhibited displacement behavior (flying, crawling, and wing flapping) close to the lamp, resulting in a phototactic response rate of 61.4% (Figure 4). Among 43 non-ovipositing female moths, 7 females exhibited displacement behavior close to the lamp, showing a phototactic response rate of 16.3%. In Test 2, 31 out of 89 male moths flew directly toward the lamp, and 17 exhibited displacement behavior close to the lamp, showing a phototactic response rate of 53.9%. Only 1 of the 78 non-ovipositing female moths flew directly toward the lamp, and 9 females exhibited displacement behavior close to the lamp, showing a phototactic response rate of 12.8%. In Test 3, none of the 30 egg-laying female moths showed a phototactic response.
These results suggested that egg-laying females were not sensitive to light sources and did not respond to phototaxis during oviposition. Non-ovipositing female moths exhibited a low phototactic response rate, averaging 14.6%. However, only 0.6% of them (one female) flew directly toward the lamp. Male moths exhibited much a higher phototactic response rate, averaging 57.7%, and 33.3% (45 males) flew directly toward the lamp.

4. Discussion

Non-ovipositing female moths exhibit phototactic flight behavior, albeit significantly weaker than that observed in male moths. The field light-trapping test revealed that all five insecticidal lamp types captured a limited number of female L. xylina during the peak emergence period (4–6 June 2019). In contrast, all lamps captured much higher numbers of male moths, with the 363 nm lamp exhibiting the highest capture rates. These field observations were further supported by the results of indoor phototactic behavior tests. Egg-laying female moths exhibited no phototactic response, while non-ovipositing females displayed a low average phototactic response rate of 14.6%, with only 0.6% flying directly toward the lamp. In contrast, male moths exhibited a significantly higher phototactic response rate, with an average of 57.7% and 33.3% flying directly toward the lamp. In addition, female L. xylina were relatively sensitive to light sources just after dark (19:00–20:00), while male moths were more sensitive to light sources around midnight.
These findings suggest that sexual dimorphism plays a crucial role in the phototactic behavior of L. xylina, with males exhibiting stronger responses likely associated with their greater flight activity and mating behavior. The observed differences in phototaxis between male and female adults highlight the diverse preferences and sensitivities of the two sexes to light sources. Even under identical conditions, male and female insects often exhibit distinct phototactic responses [3,31]. For example, most Noctuidae insects trapped by light in the wild are male, and the number of males is far more than that of females, such as Spodoptera exigua Hübner [32]
Light source characteristics, particularly wavelength and intensity, significantly influence insect phototaxis. Insects possess visual proteins sensitive to different wavelengths, including UV, blue, and green light [28,33]. For example, Drosophila melanogaster is sensitive to 345 nm, 370 nm, 480 nm, and 520 nm [28], while Narathura japonica females exhibit greater sensitivity to 460 nm and 560 nm wavelengths compared to males [34]. Light intensity also plays a crucial role. Within a specific range, increasing light intensity generally enhances insect phototactic behavior [3,35]. However, the optimal light intensity varies among species. For example, Lymantria dispar asiatica females initiate flight at light levels below 3 lux, while D. melanogaster exhibits optimal flight activity at 7 lux [36,37]. These findings provide a foundation for further investigation into the factors influencing the phototactic behavior of L. xylina and other insect species. Due to the limited light sources and the small number of female L. xylina trapped in this study, it was still necessary to deeply study the sensitive wavelengths and light intensities, especially their interaction.
Oviposition behavior significantly influences the phototactic flight behavior of female L. xylina. Previous studies have shown that both L. xylina and L. dispar japonica females cease active flight after initiating egg laying [10,38]. Indoor tests confirmed that egg-laying females exhibited no phototactic response to light stimuli. These findings suggest that the decline in flight activity after oviposition likely contributes to the low phototactic response and low capture rates of egg-laying females in light traps.
Mating status also influences female flight behavior. Studies have shown that a high proportion of female moths attracted to light sources in the evening are unmated [18,39]. This suggests that mating activity may influence female flight behavior and subsequent light attraction. Mated females may prioritize seeking suitable oviposition sites over engaging in long-distance flights, which could reduce their exposure to light traps.
Flight capability is a critical determinant of an insect’s ability to reach and be captured using light traps. Flight mill tests have revealed that female L. xylina exhibit significantly weaker flight potential compared to males. Their flight duration and distance decline rapidly with age, with most females exhibiting minimal flight activity after four days [10].
Interspecific comparisons further emphasize the importance of flight capability in determining light trap capture rates. Flight mill tests have shown that unmated female L. dispar asiatica exhibit greater flight distances than unmated female L. xylina [10,40]. This suggests that the lower female-to-male ratios observed in L. xylina light traps may be partially attributed to the weaker flight potential of female L. xylina compared to both males of the same species and females of other species such as L. dispar asiatica.
Phototactic behavior may vary among female L. xylina populations from different geographic regions. L. xylina exhibits significant geographic variation in host plant utilization, body size, sex ratio, and egg mass size [13,41]. For example, the number of eggs per egg mass in Nantou County, Taiwan [41,42], is significantly lower than the egg-carrying capacity of individual females observed in this study and the number of eggs per egg mass reported for Pingtan County, Fujian [11]. A strong positive correlation exists between body weight and egg-carrying capacity in female L. xylina. Given this relationship, it can be inferred that female L. xylina in Pingtan County may be heavier and larger than those in Nantou County. Flight mill tests further support this hypothesis, demonstrating that female moths with longer total flight distances tend to be lighter in weight, smaller in size, and exhibit lower egg-carrying capacity. These geographic variations in female L. xylina morphology and reproductive characteristics may also be influenced by flight–fecundity tradeoffs. Flight–fecundity tradeoffs are well documented in various insects, particularly those exhibiting wing dimorphism [43,44,45]. In Mythimna separata, for example, increasing flight capability requires a tradeoff with reproductive output, leading to reduced juvenile hormone levels and inhibited ovarian development. Conversely, the juvenile hormone content increased, the pre-oviposition period shortened, and the flight capability decreased [46,47,48].
In L. xylina, limited energy resources may necessitate tradeoffs between energy allocation to flight and reproduction. This may explain why female L. xylina with strong flight potential exhibit lower egg-carrying capacity. Furthermore, female L. xylina may prioritize reproductive activities over long-distance flight, resulting in reduced phototactic behavior.
This study provides valuable insights into the factors influencing female L. xylina phototaxis. However, further research is necessary to fully understand the extent of geographic variation in female phototactic behavior. This research should include (1) controlled experiments to investigate the influence of specific wavelengths and light intensities on female phototaxis, (2) studies to determine the mating status of female moths captured in light traps in different geographic locations, and (3) comparative studies of flight behavior and phototaxis in L. xylina populations from different geographic regions. These studies will provide a more comprehensive understanding of the factors influencing female L. xylina phototaxis and contribute to the development of more effective monitoring and control strategies for this important pest.

5. Conclusions

This study investigated the phototactic behavior of L. xylina through field light-trapping experiments and indoor behavioral tests. The results demonstrated that non-ovipositing female moths exhibits phototactic flight behavior, albeit significantly weaker than that observed in male moths. Male moths exhibited strong phototactic responses, with the 363 nm insecticidal lamp demonstrating the highest capture rates.
The phototaxis of L. xylina is influenced by multiple factors, including the wavelength and light intensity of light source and the flight capability of both male and female moths. Female moths are additionally affected by other factors, such as geographical population, reproductive status, and behavior characteristics. Egg-laying females exhibits no phototaxis response, while non-ovipositing females displayed limited phototactic behavior. Furthermore, phototactic behavior may vary among L. xylina populations from different geographic regions. These findings highlight the importance of considering species-specific characteristics, including sex, reproductive status, and geographic variation, when developing and implementing effective monitoring and control strategies for L. xylina.
The limited phototactic flight capability of female moths, particularly those engaged in oviposition, may have significant implications for the long-distance dispersal of this pest. This study provides valuable insights into the factors influencing the phototactic behavior of L. xylina and contributes to a better understanding of its dispersal potential and surveillance using different type of traps.
This information will be crucial for developing more effective monitoring and control strategies for this important pest and for enhancing our understanding of insect phototaxis and its ecological significance.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/insects16040338/s1: Figure S1. The environment of the outdoor experiment; Figure S2. Part of the insecticidal lamps were assembled and tested in LOIHOI; Figure S3. The phototactic behavior response tests of Lymantria xylina adults in a darkroom; Figure S4. The trapping effect of the L360 insecticidal lamp on L. xylina adults; Table S1. The number of female and male L. xylina trapped using insecticide lamps at the peak period of emergence in 2019; Table S2. The number of male L. xylina trapped using insecticide lamps at the late peak period of emergence in 2018.

Author Contributions

Methodology, J.Z., B.W., R.W. and F.Z.; formal analysis, J.Z., R.W. and M.L.; investigation, J.Z., X.P., J.L., C.X. and Y.C.; resources, B.W., J.L., X.P., C.X., Y.C. and R.W.; visualization, J.Z. and M.L.; writing—original draft preparation, J.Z. and R.W.; writing—review and editing, J.Z., R.W., B.W. and F.Z.; supervision, B.W. and F.Z.; project administration, F.Z.; funding acquisition, B.W., R.W. and F.Z. All authors edited and revised the manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

This material was made possible, in part, by a Cooperative Agreement from the United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS), grant number 8130-0369-CA. This material may not necessarily express APHIS’s views. The findings and conclusions in this article are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy. This research was also supported by the National Natural Science Foundation of China (NSFC), grant number 31600522, and by the Natural Science Foundation of Fujian Province, grant number 2017J0106.

Data Availability Statement

Data are contained within the article.

Acknowledgments

The authors thank the USDA’s APHIS for the funding. The authors thank Xiaoshan Lin and Zhenqin Zheng (Pingtan State-owned Protective Forest Farm in Fujian Province) for providing the test site. The authors also thank Meixiang Chen (the Physics Laboratory of the Physical Experiment Teaching Demonstration Center of Fujian Agriculture and Forestry University) for identifying the wavelength of the lights.

Conflicts of Interest

Author Changchun Xu was employed by the company Zhejiang LOIHOI Agriculture and Forestry Technology Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Disclaimer/Funders’ Note

The findings and conclusions in this article are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy.

References

  1. Van Grunsven, R.H.A.; Donners, M.; Boekee, K.; Tichelaar, I.; van Geffen, K.G.; Groenendijk, D.; Beredse, F.; Veenendaal, E.M. Spectral composition of light sources and insect phototaxis, with an evaluation of existing spectral response models. J. Insect Conserv. 2014, 18, 225–231. [Google Scholar] [CrossRef]
  2. Kim, K.N.; Song, H.S.; Li, C.S.; Huang, Q.Y.; Lei, C.L. Effect of several factors on the phototactic response of the oriental armyworm, Mythimna separata (Lepidoptera: Noctuidae). J. Asia-Pac. Entomol. 2018, 21, 952–957. [Google Scholar] [CrossRef]
  3. Kim, K.N.; Huang, Q.Y.; Lei, C.L. Advances in insect phototaxis and application to pest management: A review. Pest Manag. Sci. 2019, 75, 3135–3143. [Google Scholar] [CrossRef] [PubMed]
  4. De Andres-Bragado, L.; Sprecher, S.G. Mechanisms of vision in the fruit fly. Curr. Opin. Insect Sci. 2019, 36, 25–32. [Google Scholar] [CrossRef] [PubMed]
  5. Shimoda, M.; Honda, K.I. Insect reactions to light and its applications to pest management. Appl. Entomol. Zool. 2013, 48, 413–421. [Google Scholar] [CrossRef]
  6. Lafontaine, J.D.; Fibiger, M. Revised higher classification of the Noctuoidea (Lepidoptera). Can. Entomol. 2006, 138, 610–635. [Google Scholar] [CrossRef]
  7. Wang, H.; Wahlberg, N.; Holloway, J.D.; Bergsten, J.; Fan, X.; Janzen, D.H.; Hallwachs, W.; Wen, L.J.; Wang, M.; Nylin, S. Molecular phylogeny of Lymantriinae (Lepidoptera, Noctuoidea, Erebidae) inferred from eight gene regions. Cladistics 2015, 31, 579–592. [Google Scholar] [CrossRef]
  8. Wu, Z.; Ren, Y.; Chen, P.; Tian, H.; Xu, A. The complete mitochondrial genome of Lymantria xylina with phylogenetic analysis. Mitochondrial DNA B Resour. 2019, 4, 3128–3129. [Google Scholar] [CrossRef]
  9. Wang, R.; Zhang, Z.; Hu, X.; Wu, S.; Wang, J.; Zhang, F. Molecular detection and genetic diversity of casuarina moth, Lymantria xylina (Lepidoptera: Erebidae). J. Insect Sci. 2018, 18, 21. [Google Scholar] [CrossRef]
  10. Zhang, J.; Wang, B.; Ren, H.; Chen, J.; Li, J.; Sun, Y.; Cui, Y.; Wang, R.; Liu, M.; Zhang, F. Evaluation of the Potential Flight Ability of the Casuarina Moth, Lymantria xylina (Lepidoptera: Erebidae). Insects 2024, 15, 506. [Google Scholar] [CrossRef]
  11. Li, Y.G.; Chen, S.L.; Xie, Q.M.; Cai, Q.J.; Wu, J. Study on the Lymantriid moth Lymantria xylina Swinhoe. Acta Entomol. Sin. 1981, 27, 174–183. [Google Scholar] [CrossRef]
  12. Zhang, J.; Wang, B.; Wang, L.; Zuo, C.; Li, J.; Cui, Y.; Wen, X.; Cowan, D.; Wu, S.; Liu, M.; et al. Reproductive and Flight Characteristics of Lymantria xylina (Lepidoptera: Erebidae) in Fuzhou, China. Insects 2024, 15, 894. [Google Scholar] [CrossRef] [PubMed]
  13. Hwang, S.Y.; Hwang, F.C.; Shen, T.C. Shifts in developmental diet breadth of Lymantria xylina (Lepidoptera: Lymantriidae). J. Econ. Entomol. 2007, 100, 1166–1172. [Google Scholar] [CrossRef]
  14. Huang, J.; He, X.B. Diseases and Pests of Casuarina Trees in China, 1st ed.; China Forestry Publishing House: Beijing, China, 2012; p. 111. [Google Scholar]
  15. De Waard, J.R.; Mitchell, A.; Keena, M.A.; Gopurenko, D.; Boykin, L.M.; Armstrong, K.F.; Pogue, M.G.; Lima, J.; Floyd, R.; Hanner, R.H.; et al. Towards a global barcode library for Lymantria (Lepidoptera: Lymantriinae) tussock moths of biosecurity concern. PLoS ONE 2010, 5, e14280. [Google Scholar] [CrossRef]
  16. Purdue University. Asian Defoliator Pathway-Based Survey Reference. Available online: http://download.ceris.purdue.edu/file/3288 (accessed on 1 March 2014).
  17. Purdue University. Lymantria xylina Datasheet_Asian Defoliator. Available online: http://download.ceris.purdue.edu/file/2288 (accessed on 5 February 2014).
  18. Pogue, M.; Schaefer, P.W. A Review of Selected Species of Lymantria Hübner (1819) (Lepidoptera: Noctuidae: Lymantriinae) from Subtropical and Temperate Regions of Asia, Including the Descriptions of Three New Species, Some Potentially Invasive to North America; Forest Health Technology Enterprise Team: Washington, DC, USA, 2007. [Google Scholar]
  19. CABI. Lymantria xylina (Casuarina Tussock Moth). Available online: https://www.cabidigitallibrary.org/doi/pdf/10.1079/cabicompendium.31815 (accessed on 16 September 2022).
  20. Summerville, K.S.; Boulware, M.J.; Veech, J.A.; Crist, T.O. Spatial variation in species diversity and composition of forest Lepidoptera in eastern deciduous forests of North America. Conserv. Biol. 2003, 17, 1045–1057. [Google Scholar] [CrossRef]
  21. Keena, M.A.; Côté, M.J.; Grinberg, P.S.; Wallner, W.E. World distribution of female flight and genetic variation in Lymantria dispar (Lepidoptera: Lymantriidae). Environ. Entomol. 2014, 37, 636–649. [Google Scholar] [CrossRef]
  22. Wu, C.Y.; Wang, C.H. Characterization and polyhedrin gene cloning of Lymantria xylina multiple nucleopolyhedrovirus. J. Invertebr. Pathol. 2005, 88, 238–246. [Google Scholar] [CrossRef]
  23. Lee, K.S.; Kang, T.H.; Jeong, J.W.; Ryu, D.P.; Lee, H.S. Taxonomic review of the genus Lymantria (Lepidoptera: Erebidae: Lymantriinae) in Korea. Entomol. Res. 2015, 45, 225–234. [Google Scholar] [CrossRef]
  24. Kang, T.H.; Lee, K.S.; Lee, H.S. DNA barcoding of the Korean Lymantria Hübner, 1819 (Lepidoptera: Erebidae: Lymantriinae) for quarantine inspection. J. Econ. Entomol. 2015, 108, 1596–1611. [Google Scholar] [CrossRef]
  25. Kang, T.H.; Choi, D.S.; Hong, K.J.; Park, S. Monitoring of hitchhiker insect pests collected on foreign vessels entering Korea using by DNA barcodes. J. Asia-Pac. Entomol. 2023, 26, 102136. [Google Scholar] [CrossRef]
  26. Yeh, S.T.; Liao, C.T.; Ko, W.F.; Pai, K.F. Light attractive evaluation and insecticide trials of casuarina moth (Lymantria xylina Swinhoe) in Bagua Mountain area. Res. Rep. Agric. Improv. Field Taizhong Dist. 2010, 107, 47–59. [Google Scholar] [CrossRef]
  27. Peng, J.; Chen, K.; Zheng, X.; Chen, D.; Xu, D. Biological characteristics of Lymantria xylina and its prevention and control measures. Chin. Countrys. Well-Off Technol. 2009, 05, 55–57. [Google Scholar] [CrossRef]
  28. Van der Kooi, C.J.; Stavenga, D.G.; Arikawa, K.; Belušič, G.; Kelber, A. Evolution of insect color vision: From spectral sensitivity to visual ecology. Annu. Rev. Entomol. 2021, 66, 435–461. [Google Scholar] [CrossRef] [PubMed]
  29. Luan, Q.; Du, Y.; Yun, L.; Wang, Q.; Wang, W.; Wang, J. Light trap experiments against Lymantria dispar adults. For. Pest Dis. 2014, 33, 36–40. [Google Scholar] [CrossRef]
  30. Zhang, J.; Zuo, C.; Wang, R.; Liang, G.; Wang, B.; Zhang, F. Studies on the Distribution of Lymantria xylina egg masses in Field. Highlights Sci. Online 2018, 11, 1543–1551. [Google Scholar]
  31. Garris, H.W.; Snyder, J.A. Sex-specific attraction of moth species to ultraviolet light traps. Southeast. Nat. 2010, 9, 427–434. [Google Scholar] [CrossRef]
  32. Allen, C.E.; Zwaan, B.J.; Brakefield, P.M. Evolution of sexual dimorphism in the Lepidoptera. Annu. Rev. Entomol. 2010, 56, 445–464. [Google Scholar] [CrossRef]
  33. Crook, D.J.; Hull-Sanders, H.M.; Hibbard, E.L.; Mastro, V.C. A comparison of electrophysiologically determined spectral responses in six subspecies of Lymantria. J. Econ. Entomol. 2014, 107, 667–674. [Google Scholar] [CrossRef]
  34. Mafuku, M.; Shimizu, I.; Imai, H.; Shichida, Y. Sexual difference in color sense in a lycaenid butterfly, Narathura japonica. Zool. Sci. 2007, 24, 611–613. [Google Scholar] [CrossRef]
  35. Park, J.H.; Lee, H.S. Phototactic behavioral response of agricultural insects and stored-product insects to light-emitting diodes (LEDs). Appl. Biol. Chem. 2017, 60, 137–144. [Google Scholar] [CrossRef]
  36. Chen, F.; Shi, J.; Keena, M. Evaluation of the effects of light intensity and time interval after the start of scotophase on the female flight propensity of Asian gypsy moth (Lepidoptera: Erebidae). Environ. Entomol. 2016, 45, 404–409. [Google Scholar] [CrossRef] [PubMed]
  37. Ho, M.; Mawji, N.; Meng, S.W.; Ng, D.T.; Smyrnis, N.E. The Effect of Exposure to Varying Light Wavelengths During Development on Locomotor Speed of Adult Drosophila Melanogaster. Available online: https://ojs.library.ubc.ca/index.php/expedition/article/download/184810/184489 (accessed on 20 February 2014).
  38. Iwaizumi, R.; Arakawa, K.; Koshio, C. Nocturnal flight activities of the female Asian gypsy moth, Lymantria dispar (Linnaeus) (Lepidoptera: Lymantriidae). Appl. Entomol. Zool. 2010, 45, 121–128. [Google Scholar] [CrossRef]
  39. Schaefer, P.W. Mass flights of Lymantria dispar japonica and Lymantria mathura (Erebidae: Lymantriinae) to commercial lighting, with notes on female viability and fecundity. J. Lepid. Soc. 2014, 2, 68. [Google Scholar] [CrossRef]
  40. Yang, F.; Luo, Y.; Shi, J. The influence of geographic population, age, and mating status on the flight activity of the Asian gypsy moth Lymantria dispar (Lepidoptera: Erebidae) in China. Appl. Entomol. Zool. 2017, 52, 265–270. [Google Scholar] [CrossRef]
  41. Yeh, S.; Liao, C.; Chen, C.; Ko, W. Biological characteristics of Casuarina Moth Lymantria xylina (Lepidoptera: Lymantriidae) in Bagua Mountain Area. Res. Rep. Agric. Improv. Field Taizhong Dist. 2006, 93, 41–54. [Google Scholar] [CrossRef]
  42. Shen, T.C.; Shae, Y.S.; Liu, C.S.; Tan, C.W.; Hwang, S.Y. Relationships between egg mass size and egg number per egg mass in the casuarina moth, Lymantria xylina (Lepidoptera: Lymantriidae). Environ. Entomol. 2003, 32, 752–755. [Google Scholar] [CrossRef]
  43. Zera, A.J.; Denno, R.F. Physiology and ecology of dispersal polymorphism in insects. Annu. Rev. Entomol. 1997, 42, 207–230. [Google Scholar] [CrossRef] [PubMed]
  44. Guerra, P.A. Evaluating the life-history trade-off between dispersal capability and reproduction in wing dimorphic insects: A meta-analysis. Biol. Rev. 2011, 86, 813–835. [Google Scholar] [CrossRef] [PubMed]
  45. Tigreros, N.; Davidowitz, G. Flight-fecundity tradeoffs in wing-monomorphic insects. Adv. Insect Physiol. 2019, 56, 1–41. [Google Scholar] [CrossRef]
  46. Zhang, L.; Cheng, L.; Chapman, J.W.; Sappington, T.W.; Liu, J.; Cheng, Y.; Jiang, X. Juvenile hormone regulates the shift from migrants to residents in adult oriental armyworm, Mythimna separata. Sci. Rep. 2020, 10, 11626. [Google Scholar] [CrossRef]
  47. Lv, W.; Zeng, L.; Zhang, Z.; He, H.; Wang, F.; Xie, X. Effects of juvenile hormone analog and days after emergence on the reproduction of oriental armyworm, Mythimna separata (Lepidoptera: Noctuidae) populations. Insects 2022, 13, 506. [Google Scholar] [CrossRef] [PubMed]
  48. Pang, Y.; Zeng, Y.; Zhu, D.H. Flight and flight energy accumulation related to the daily rhythm of juvenile hormone titer in the wing-dimorphic cricket Velarifictorus aspersus. Entomol. Exp. Appl. 2023, 171, 878–886. [Google Scholar] [CrossRef]
Insects 16 00338 g001
Figure 1. The trapping effects of different insecticidal lamps on Lymantria xylina males: (a) at the peak period of emergence and (b) at the late peak period of emergence. The data in the figure are the mean ± SE; different lowercase letters represent significant differences in the adjusted daily trapping of male moths using different insecticidal lamps (p < 0.05, Duncan’s test).
Figure 1. The trapping effects of different insecticidal lamps on Lymantria xylina males: (a) at the peak period of emergence and (b) at the late peak period of emergence. The data in the figure are the mean ± SE; different lowercase letters represent significant differences in the adjusted daily trapping of male moths using different insecticidal lamps (p < 0.05, Duncan’s test).
Insects 16 00338 g001
Insects 16 00338 g002
Figure 2. The adjusted daily trapping of L360 insecticidal lamps with different powers on male L. xylina: (a) at the peak period of emergence and (b) at the late peak period of emergence. Data in the figure are expressed as the mean ± SE; different lowercase letters indicate significant differences in adjusted daily trapping of L360 insecticidal lamps with different powers on male L. xylina at the level (p < 0.05, Duncan’s test).
Figure 2. The adjusted daily trapping of L360 insecticidal lamps with different powers on male L. xylina: (a) at the peak period of emergence and (b) at the late peak period of emergence. Data in the figure are expressed as the mean ± SE; different lowercase letters indicate significant differences in adjusted daily trapping of L360 insecticidal lamps with different powers on male L. xylina at the level (p < 0.05, Duncan’s test).
Insects 16 00338 g002
Insects 16 00338 g003
Figure 3. Comparison of weight and egg-carrying capacity between light-trapped and indoor-emerged adults: (a) weight, (b) egg-carrying capacity, and (c) correlation between weight and egg-carrying capacity. An independent samples t-test was conducted to compare the two groups, with black dots indicating outliers. Linear regression analysis was performed using the Levenberg-Marquardt algorithm.
Figure 3. Comparison of weight and egg-carrying capacity between light-trapped and indoor-emerged adults: (a) weight, (b) egg-carrying capacity, and (c) correlation between weight and egg-carrying capacity. An independent samples t-test was conducted to compare the two groups, with black dots indicating outliers. Linear regression analysis was performed using the Levenberg-Marquardt algorithm.
Insects 16 00338 g003
Insects 16 00338 g004
Figure 4. Phototactic response behavior of L. xylina adults with different reproductive states indoors.
Figure 4. Phototactic response behavior of L. xylina adults with different reproductive states indoors.
Insects 16 00338 g004
Table 1. Configuration and wavelength information of different insecticide lamps.
Table 1. Configuration and wavelength information of different insecticide lamps.
No.Central Wavelength (nm)Voltage (V)Power (W)ManufacturerElectric Insecticidal Part
L3603631215GuanhongyaGP-LH18B
3631215LOIHOIGP-LH18B
36322025LOIHOIGP-LH2203
36322035LOIHOIGP-LH2203
L3653651215LOIHOIGP-LH18B
L3703681215GuanhongyaGP-LH18B
L3803781215GuanhongyaGP-LH18B
L4054391215GuanhongyaGP-LH18B
Table 2. The number and sex ratio of L. xylina trapped using insecticide lamps at the peak and late peak periods of emergence.
Table 2. The number and sex ratio of L. xylina trapped using insecticide lamps at the peak and late peak periods of emergence.
YearEmergence PeriodLampTotal TrappingMaximum Daily Trapping
FemaleMaleSex RatioFemaleMaleSex Ratio
2018Late peak periodL3600160040
(6 days)L365080030
L370040030
L380040020
L405050030
2019Peak periodL360210461:52317731:186
(3 days)L36515021:50212341:212
L37036551:21823121:130
L38013641:36412001:112
L40523351:16821471:62
Table 3. Comparison of the number of male and female L. xylina trapped using insecticide lamps during different periods at the peak period of emergence.
Table 3. Comparison of the number of male and female L. xylina trapped using insecticide lamps during different periods at the peak period of emergence.
PeriodMean ± S.E.Cumulative Percent
FemaleMaleFemaleMale
19:00–20:001.3 ± 1.3 a14.3 ± 5.5 c44.41.5
20:00–21:001.0 ± 0.6 a35.0 ± 9.0 bc77.85.1
21:00–22:000.3 ± 0.3 a117.0 ± 37.0 abc88.917.2
22:00–23:000.3 ± 0.3 a212.3 ± 80.9 ab10039.1
23:00–0:000 a285.0 ± 89.3 a10068.6
0:00–1:000 a179.7 ± 94.6 abc10087.2
1:00–2:000 a90.0 ± 54.3 bc10096.5
2:00–3:000 a24.3 ± 9.8 c10099.0
3:00–4:000 a9.7 ± 4.2 c100100
Note: different lowercase letters indicate significant differences in the capture numbers of male and female L. xylina during the different periods at the level (p < 0.05, Duncan’s test).
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Zhang, J.; Wang, B.; Wang, R.; Peng, X.; Li, J.; Xu, C.; Cui, Y.; Liu, M.; Zhang, F. Phototaxis Characteristics of Lymantria xylina (Lepidoptera: Erebidae). Insects 2025, 16, 338. https://doi.org/10.3390/insects16040338

AMA Style

Zhang J, Wang B, Wang R, Peng X, Li J, Xu C, Cui Y, Liu M, Zhang F. Phototaxis Characteristics of Lymantria xylina (Lepidoptera: Erebidae). Insects. 2025; 16(4):338. https://doi.org/10.3390/insects16040338

Chicago/Turabian Style

Zhang, Jifeng, Baode Wang, Rong Wang, Xiancheng Peng, Junnan Li, Changchun Xu, Yonghong Cui, Mengxia Liu, and Feiping Zhang. 2025. "Phototaxis Characteristics of Lymantria xylina (Lepidoptera: Erebidae)" Insects 16, no. 4: 338. https://doi.org/10.3390/insects16040338

APA Style

Zhang, J., Wang, B., Wang, R., Peng, X., Li, J., Xu, C., Cui, Y., Liu, M., & Zhang, F. (2025). Phototaxis Characteristics of Lymantria xylina (Lepidoptera: Erebidae). Insects, 16(4), 338. https://doi.org/10.3390/insects16040338

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop