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Insects, Volume 3, Issue 2 (June 2012), Pages 367-592

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Research

Jump to: Review

Open AccessArticle Individual Behavior of Workers of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae) on Consecutive Days of Tunnel Construction
Insects 2012, 3(2), 367-377; doi:10.3390/insects3020367
Received: 20 February 2012 / Revised: 1 March 2012 / Accepted: 16 March 2012 / Published: 23 March 2012
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Abstract
This study examines the individual behavior of workers of the Formosan subterranean termite, Coptotermes formosanus Shirkai, on two consecutive days of tunnel construction. In each trial, a group of 30 termite workers was observed continuously during the first 60 min of construction of a new tunnel on two consecutive days. On each day, an average of 68% of individuals did not participate in tunnel construction, 19% spent < 25 min tunneling, and 13% spent ≥ 25 min tunneling. There were specific individuals that did most of the work in the construction of new tunnels on both days. An individual that spent at least 25 min tunneling on Day 1 was significantly more likely to spend at least 25 min tunneling on Day 2 than individuals that spent < 25 min tunneling on Day 1. When individuals were ranked based on the time spent tunneling on Day 1 and Day 2, there were individuals ranked as one of the top four excavators on both days in three of the four groups. These results indicate that there is evidence of task allocation by termite workers during the construction of a new tunnel. Full article
(This article belongs to the Special Issue Feature Papers 2012)
Open AccessArticle Differences in Immune Defense Evasion of Selected Inbred Lines of Heterorhabditis Bacteriophora in Two White Grub Species
Insects 2012, 3(2), 378-389; doi:10.3390/insects3020378
Received: 7 February 2012 / Revised: 1 March 2012 / Accepted: 14 March 2012 / Published: 23 March 2012
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Abstract
We determined virulence of seven Heterorhabditis bacteriophora strain GPS11 inbred lines possessing superior infective juvenile longevity, and heat and ultra violet radiation tolerance against white grubs Popillia japonica and Cyclocephala borealis. At 1 and 2 weeks after treatment, inbred line A2 [...] Read more.
We determined virulence of seven Heterorhabditis bacteriophora strain GPS11 inbred lines possessing superior infective juvenile longevity, and heat and ultra violet radiation tolerance against white grubs Popillia japonica and Cyclocephala borealis. At 1 and 2 weeks after treatment, inbred line A2 was significantly more virulent towards P. japonica compared to the parent strain GPS11 and inbred lines A7, A8, A12 and A21; and line A2 caused significantly higher C. borealis mortality than lines A6 and A12. Penetration, encapsulation and survival of two inbred lines, A2 and A12, that showed the highest and lowest virulence against both grub species were then assessed. There were no differences between the two lines for the total number of nematodes penetrated in either P. japonica or C. borealis within the first 24 h, but a significantly higher percentage of penetrated nematodes were alive in line A2 compared to the line A12 in both grub species. P. japonica immune response over time to hemocoel-injected nematodes of A2, A12 and the parent strain was further investigated. While all injected nematodes were encapsulated at 6 h post injection, non-encapsulated living nematodes were detected at 12 and 24 h post injection, showing the breakage out of encapsulation. A higher percentage of non-encapsulated living nematodes and a lower percentage of dead nematodes were found in line A2 as compared to the line A12 after 12 h post injection. These data suggest that virulence differences in the studied H. bacteriophora inbred lines are not due to differences in nematode penetration or recognition by the grub immune system, but are related to the ability of the infective juveniles to break out of encapsulation. Full article
(This article belongs to the Special Issue Pest Control and Management)
Open AccessArticle Termite Resistance of Thermally-Modified Dendrocalamus asper (Schultes f.) Backer ex Heyne
Insects 2012, 3(2), 390-395; doi:10.3390/insects3020390
Received: 8 February 2012 / Revised: 15 March 2012 / Accepted: 16 March 2012 / Published: 27 March 2012
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Abstract
The effects of thermal modification on the resistance of Dendrocalamus asper against Microcerotermes losbañosensis were investigated after exposure to virgin coconut oil at 140–200 °C for 30–120 min. The results showed that heat treatment significantly improved bamboo’s resistance to termites based on [...] Read more.
The effects of thermal modification on the resistance of Dendrocalamus asper against Microcerotermes losbañosensis were investigated after exposure to virgin coconut oil at 140–200 °C for 30–120 min. The results showed that heat treatment significantly improved bamboo’s resistance to termites based on mass losses and visual observations. The enhancement was highest at 200 °C. Prolonged treatment had a positive effect on the resistance at lower temperatures only. Full article
Open AccessArticle Termite-Susceptible Species of Wood for Inclusion as a Reference in Indonesian Standardized Laboratory Testing
Insects 2012, 3(2), 396-401; doi:10.3390/insects3020396
Received: 17 February 2012 / Revised: 24 February 2012 / Accepted: 19 March 2012 / Published: 28 March 2012
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Abstract
Standardized laboratory testing of wood and wood-based products against subterranean termites in Indonesia (SNI 01.7207-2006) (SNI) has no requirement for the inclusion of a comparative reference species of wood (reference control). This is considered a weakness of the Indonesian standard. Consequently, a [...] Read more.
Standardized laboratory testing of wood and wood-based products against subterranean termites in Indonesia (SNI 01.7207-2006) (SNI) has no requirement for the inclusion of a comparative reference species of wood (reference control). This is considered a weakness of the Indonesian standard. Consequently, a study was undertaken to identify a suitable Indonesian species of community wood that could be used as a reference control. Four candidate species of community woods: Acacia mangium, Hevea brasiliensis, Paraserianthes falcataria and Pinus merkusii were selected for testing their susceptibility to feeding by Coptotermes formosanus. Two testing methods (SNI and the Japanese standard method JIS K 1571-2004) were used to compare the susceptibility of each species of wood. Included in the study was Cryptomeria japonica, the reference control specified in the Japanese standard. The results of the study indicated that P. merkusii is a suitable reference species of wood for inclusion in laboratory tests against subterranean termites, conducted in accordance with the Indonesian standard (SNI 01.7207-2006). Full article
Open AccessArticle Comparison of Three Bed Bug Management Strategies in a Low-Income Apartment Building
Insects 2012, 3(2), 402-409; doi:10.3390/insects3020402
Received: 18 February 2012 / Revised: 22 February 2012 / Accepted: 20 March 2012 / Published: 2 April 2012
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Abstract
Bed bug (Cimex lectularius L.) infestations are currently controlled by a variety of non-chemical and chemical methods. There have been few studies on the comparative effectiveness of these control techniques. We evaluated three bed bug management strategies in an apartment building: [...] Read more.
Bed bug (Cimex lectularius L.) infestations are currently controlled by a variety of non-chemical and chemical methods. There have been few studies on the comparative effectiveness of these control techniques. We evaluated three bed bug management strategies in an apartment building: (1) non-chemical methods only (n = 9); (2) insecticides only (n = 6); and (3) integrated pest management including both non-chemical methods and insecticides (n = 9). The apartments were one-bedroom units occupied by seniors or people with disabilities. Bed bug numbers in each apartment were determined by visual inspection and/or installing intercepting devices under bed and sofa legs. The median (min, max) bed bug counts in the non-chemical methods only, insecticides only, and integrated pest management (IPM) treatment were: 4 (1, 57), 19 (1, 250), and 14 (1, 219), respectively prior to the treatments. The apartments were retreated if found necessary during biweekly to monthly inspections. After 10 weeks, bed bugs were found to be eliminated from 67, 33, and 44% of the apartments in the three treatment groups, respectively. The final (after 10 weeks) median (min, max) bed bug counts in the non-chemical methods only, insecticides only, and IPM treatment were: 0 (0, 134), 11.5 (0, 58), and 1 (0, 38), respectively. There were no significant differences in the speed of bed bug count reduction or the final bed bug counts. Lack of resident cooperation partially contributed to the failure in eliminating bed bugs from some of the apartments. Results of this study suggest that non-chemical methods can effectively eliminate bed bugs in lightly infested apartments. Full article
(This article belongs to the Special Issue Feature Papers 2012)
Open AccessArticle Japanese Interest in “Hotaru” (Fireflies) and “Kabuto-Mushi” (Japanese Rhinoceros Beetles) Corresponds with Seasonality in Visible Abundance
Insects 2012, 3(2), 424-431; doi:10.3390/insects3020424
Received: 17 March 2012 / Revised: 31 March 2012 / Accepted: 2 April 2012 / Published: 10 April 2012
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Abstract
Seasonal changes in the popularity of fireflies [usually Genji-fireflies (Luciola cruciata Motschulsky) in Japan] and Japanese rhinoceros beetles [Allomyrina dichotoma (Linne)] were investigated to examine whether contemporary Japanese are interested in visible emergence of these insects as seasonal events. The [...] Read more.
Seasonal changes in the popularity of fireflies [usually Genji-fireflies (Luciola cruciata Motschulsky) in Japan] and Japanese rhinoceros beetles [Allomyrina dichotoma (Linne)] were investigated to examine whether contemporary Japanese are interested in visible emergence of these insects as seasonal events. The popularity of fireflies and Japanese rhinoceros beetles was assessed by the Google search volume of their Japanese names, “Hotaru” and “Kabuto-mushi” in Japanese Katakana script using Google Trends. The search volume index for fireflies and Japanese rhinoceros beetles was distributed across seasons with a clear peak in only particular times of each year from 2004 to 2011. In addition, the seasonal peak of popularity for fireflies occurred at the beginning of June, whereas that for Japanese rhinoceros beetles occurred from the middle of July to the beginning of August. Thus seasonal peak of each species coincided with the peak period of the emergence of each adult stage. These findings indicated that the Japanese are interested in these insects primarily during the time when the two species are most visibly abundant. Although untested, this could suggest that fireflies and Japanese rhinoceros beetles are perceived by the general public as indicators or symbols of summer in Japan. Full article
(This article belongs to the Special Issue Feature Papers 2012)
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Open AccessArticle Bed Bug (Cimex lectularius L.) Population Composition as Determined by Baited Traps
Insects 2012, 3(2), 442-452; doi:10.3390/insects3020442
Received: 17 April 2012 / Revised: 26 April 2012 / Accepted: 27 April 2012 / Published: 30 April 2012
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Abstract
Two established field populations of bed bugs were sampled using host-mimicking traps baited with a combination of CO2, heat and a synthetic kairomone. The proportion of first instar nymphs (between 52% and 78% of all captured insects) was significantly higher than reported [...] Read more.
Two established field populations of bed bugs were sampled using host-mimicking traps baited with a combination of CO2, heat and a synthetic kairomone. The proportion of first instar nymphs (between 52% and 78% of all captured insects) was significantly higher than reported in previous studies, which had employed different sampling methods. The proportion of adults was correspondingly much lower than previously reported, between 5% and 7% of total capture. As many as 120 bed bugs were captured in a single trap in one night; the variation in catches between sampling locations within the same room and between days at the same location indicates that multiple nights of trapping may be required to obtain an accurate representation of population structure. Full article
(This article belongs to the Special Issue Feature Papers 2012)
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Open AccessArticle Shared Ancestry of Symbionts? Sagrinae and Donaciinae (Coleoptera, Chrysomelidae) Harbor Similar Bacteria
Insects 2012, 3(2), 473-491; doi:10.3390/insects3020473
Received: 28 March 2012 / Revised: 11 April 2012 / Accepted: 17 April 2012 / Published: 7 May 2012
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Abstract
When symbioses between insects and bacteria are discussed, the origin of a given association is regularly of interest. We examined the evolution of the symbiosis between reed beetles (Coleoptera, Chrysomelidae, Donaciinae) and intracellular symbionts belonging to the Enterobacteriaceae. We analyzed the partial [...] Read more.
When symbioses between insects and bacteria are discussed, the origin of a given association is regularly of interest. We examined the evolution of the symbiosis between reed beetles (Coleoptera, Chrysomelidae, Donaciinae) and intracellular symbionts belonging to the Enterobacteriaceae. We analyzed the partial sequence of the 16S rRNA to assess the phylogenetic relationships with bacteria we found in other beetle groups (Cerambycidae, Anobiidae, other Chrysomelidae). We discuss the ecology of each association in the context of the phylogenetic analysis. The bacteria in Sagra femorata (Chrysomelidae, Sagrinae) are very closely related to those in the Donaciinae and are located in similar mycetomes. The Sagrinae build a cocoon for pupation like the Donaciinae, in which the bacteria produce the material required for the cocoon. These aspects support the close relationship between Sagrinae and Donaciinae derived in earlier studies and make a common ancestry of the symbioses likely. Using PCR primers specific for fungi, we found Candida sp. in the mycetomes of a cerambycid beetle along with the bacteria. Full article
(This article belongs to the Special Issue Symbiosis: A Source of Evolutionary Innovation in Insects)
Open AccessArticle Resistance of Particleboards Made from Fast-Growing Wood Species to Subterranean Termite Attack
Insects 2012, 3(2), 532-537; doi:10.3390/insects3020532
Received: 8 April 2012 / Revised: 23 April 2012 / Accepted: 14 May 2012 / Published: 29 May 2012
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Abstract
Laboratory-made particleboards were tested for their resistance to subterranean termite, Coptotermes curvignathus Holmgren (Order Isoptera, Family Termitidae) by Indonesian standard SNI 01.7207–2006, during four weeks and at the end of the test their mass loss percentage and feeding rate were determined. Particleboards [...] Read more.
Laboratory-made particleboards were tested for their resistance to subterranean termite, Coptotermes curvignathus Holmgren (Order Isoptera, Family Termitidae) by Indonesian standard SNI 01.7207–2006, during four weeks and at the end of the test their mass loss percentage and feeding rate were determined. Particleboards consisted of: jabon (Anthocephalus cadamba, Family Rubiacea) with a density of 0.41 g/cm3; sungkai (Peronema canescens, Family Verbenaceae) with a density of 0.46 g/cm3; mangium (Acacia mangium, Family Rhamnaceae) with a density of 0.60 g/cm3 separately and the three species mixture at a rate of 1:1:1. Densities of the boards were targetted at 0.60 g/cm3 and 0.80 g/cm3 by using 12% urea formaldehyde as binder with 2% paraffin as additive based on oven dry wood particle weight. The hand-formed mats and hot-pressing at 130 °C and 2.45 MPa for 10 min were applied. The results showed that particleboards density did not affect mass loss and feeding rate, but the particleboards made from higher density wood resulted in higher resistance to subterranean termite attack. The most resistant particleboards were made of magium, followed by sungkai, mixed species, and jabon. Full article
Open AccessArticle Neotenic Phenotype and Sex Ratios Provide Insight into Developmental Pathways in Reticulitermes flavipes (Isoptera: Rhinotermitidae)
Insects 2012, 3(2), 538-552; doi:10.3390/insects3020538
Received: 16 April 2012 / Revised: 13 May 2012 / Accepted: 14 May 2012 / Published: 4 June 2012
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Abstract
Several thousand Reticulitermes flavipes (Kollar) including worker, nymph, soldier, neotenic and alate castes were collected from three pine logs brought into the laboratory on dates five years apart. The neotenics, all nymphoid, were divided into three groups based on the extent of [...] Read more.
Several thousand Reticulitermes flavipes (Kollar) including worker, nymph, soldier, neotenic and alate castes were collected from three pine logs brought into the laboratory on dates five years apart. The neotenics, all nymphoid, were divided into three groups based on the extent of cuticle pigmentation and termed regular neotenics (RN), black-headed neotenics (BHN) or black neotenics (BN). All castes, from Log A, in 2008, provided a neutral sex ratio except BHN (N = 378) and BN (N = 51) which were exclusively male while the soldiers (N = 466) were female-biased. This information suggests that there is a sex-linked bifurcation along the path for termite development with a male-biased neotenic or female-biased soldier as the choice. In contrast, termites collected in 2004 from Log B provided sex ratios that included a female biased RN (N = 1017), a neutral soldier (N = 258) and male biased BHN (N = 99) and workers (N = 54). Log C, collected in 2009, provided female biased soldiers (N = 32), RNs (N = 18) and BHNs (N = 4) and only male BN (N = 5). Eight laboratory cultures, ranging in age from five to 14 years old, also were sampled and all castes sexed. The census included a 14-year old queen-right colony, an 8-year old polyandrous colony and six colonies provided nymphs and male-biased worker populations. Together these data indicate a flexible caste determination system providing a unique opportunity for a better understanding of the flexible developmental options available in R. flavipes that we discuss relative to the literature on Reticulitermes ontogeny. Full article
(This article belongs to the Special Issue Feature Papers 2012)

Review

Jump to: Research

Open AccessReview Reciprocal Trophic Interactions and Transmission of Blood Parasites between Mosquitoes and Frogs
Insects 2012, 3(2), 410-423; doi:10.3390/insects3020410
Received: 13 March 2012 / Revised: 20 March 2012 / Accepted: 21 March 2012 / Published: 3 April 2012
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Abstract
The relationship between mosquitoes and their amphibian hosts is a unique, reciprocal trophic interaction. Instead of a one-way, predator-prey relationship, there is a cyclical dance of avoidance and attraction. This has prompted spatial and temporal synchrony between organisms, reflected in emergence time [...] Read more.
The relationship between mosquitoes and their amphibian hosts is a unique, reciprocal trophic interaction. Instead of a one-way, predator-prey relationship, there is a cyclical dance of avoidance and attraction. This has prompted spatial and temporal synchrony between organisms, reflected in emergence time of mosquitoes in the spring and choice of habitat for oviposition. Frog-feeding mosquitoes also possess different sensory apparatuses than do their mammal-feeding counterparts. The reciprocal nature of this relationship is exploited by various blood parasites that use mechanical, salivary or trophic transmission to pass from mosquitoes to frogs. It is important to investigate the involvement of mosquitoes, frogs and parasites in this interaction in order to understand the consequences of anthropogenic actions, such as implementing biocontrol efforts against mosquitoes, and to determine potential causes of the global decline of amphibian species. Full article
(This article belongs to the Special Issue Trophic Interactions of Insects and Amphibians)
Open AccessReview Trophic Interactions Between Insects and Stream-Associated Amphibians in Steep, Cobble-Bottom Streams of the Pacific Coast of North America
Insects 2012, 3(2), 432-441; doi:10.3390/insects3020432
Received: 16 February 2012 / Revised: 22 March 2012 / Accepted: 26 March 2012 / Published: 10 April 2012
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Abstract
Two native, stream-associated amphibians are found in coastal streams of the west coast of North America, the tailed frog and the coastal giant salamander, and each interacts with stream insects in contrasting ways. For tailed frogs, their tadpoles are the primary life [...] Read more.
Two native, stream-associated amphibians are found in coastal streams of the west coast of North America, the tailed frog and the coastal giant salamander, and each interacts with stream insects in contrasting ways. For tailed frogs, their tadpoles are the primary life stage found in steep streams and they consume biofilm from rock surfaces, which can have trophic and non-trophic effects on stream insects. By virtue of their size the tadpoles are relatively insensitive to stream insect larvae, and tadpoles are capable of depleting biofilm levels directly (exploitative competition), and may also “bulldoze” insect larvae from the surfaces of stones (interference competition). Coastal giant salamander larvae, and sometimes adults, are found in small streams where they prey primarily on stream insects, as well as other small prey. This predator-prey interaction with stream insects does not appear to result in differences in the stream invertebrate community between streams with and without salamander larvae. These two examples illustrate the potential for trophic and non-trophic interactions between stream-associated amphibians and stream insects, and also highlights the need for further research in these systems. Full article
(This article belongs to the Special Issue Trophic Interactions of Insects and Amphibians)
Open AccessReview What is Next in Bark Beetle Phylogeography?
Insects 2012, 3(2), 453-472; doi:10.3390/insects3020453
Received: 16 April 2012 / Revised: 25 April 2012 / Accepted: 26 April 2012 / Published: 7 May 2012
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Abstract
Bark beetle species within the scolytid genera Dendroctonus, Ips, Pityogenes and Tomicus are known to cause extensive ecological and economical damage in spruce and pine forests during epidemic outbreaks all around the world. Dendroctonus ponderosae poses the most recent example [...] Read more.
Bark beetle species within the scolytid genera Dendroctonus, Ips, Pityogenes and Tomicus are known to cause extensive ecological and economical damage in spruce and pine forests during epidemic outbreaks all around the world. Dendroctonus ponderosae poses the most recent example having destroyed almost 100,000 km2 of conifer forests in North America. The success and effectiveness of scolytid species lies mostly in strategies developed over the course of time. Among these, a complex system of semiochemicals promotes the communication and aggregation on the spot of infestation facilitating an en masse attack against a host tree’s defenses; or an association with fungi that evolved either in the form of nutrition (ambrosia fungi) or even by reducing the resistance of host trees (blue-stain fungi). Although often specific to a tree genus or species, some bark beetles are polyphagous and have the ability to switch on to new hosts and extend their host range (i.e., between conifer genera such as Pityogenes chalcographus or even from conifer to deciduous trees as Polygraphus grandiclava). A combination of these capabilities in concert with life history or ecological traits explains why bark beetles are considered interesting subjects in evolutionary studies. Several bark beetle species appear in phylogeographic investigations, in an effort to improve our understanding of their ecology, epidemiology and evolution. In this paper investigations that unveil the phylogeographic history of bark beetles are reviewed. A close association between refugial areas and postglacial migration routes that insects and host trees have followed in the last 15,000 BP has been suggested in many studies. Finally, a future perspective of how next generation sequencing will influence the resolution of phylogeographic patterns in the coming years is presented. Utilization of such novel techniques will provide a more detailed insight into the genome of scolytids facilitating at the same time the application of neutral and non-neutral markers. The latter markers in particular promise to enhance the study of eco-physiological reaction types like the so-called pioneer beetles or obligate diapausing individuals. Full article
(This article belongs to the Special Issue Phylogeographic Syntheses)
Open AccessReview Eicosanoids: Exploiting Insect Immunity to Improve Biological Control Programs
Insects 2012, 3(2), 492-510; doi:10.3390/insects3020492
Received: 15 March 2012 / Revised: 24 April 2012 / Accepted: 9 May 2012 / Published: 16 May 2012
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Abstract
Insects, like all invertebrates, express robust innate, but not adaptive, immune reactions to infection and invasion. Insect immunity is usually resolved into three major components. The integument serves as a physical barrier to infections. Within the hemocoel, the circulating hemocytes are the [...] Read more.
Insects, like all invertebrates, express robust innate, but not adaptive, immune reactions to infection and invasion. Insect immunity is usually resolved into three major components. The integument serves as a physical barrier to infections. Within the hemocoel, the circulating hemocytes are the temporal first line of defense, responsible for clearing the majority of infecting bacterial cells from circulation. Specific cellular defenses include phagocytosis, microaggregation of hemocytes with adhering bacteria, nodulation and encapsulation. Infections also stimulate the humoral component of immunity, which involves the induced expression of genes encoding antimicrobial peptides and activation of prophenoloxidase. These peptides appear in the hemolymph of challenged insects 6–12 hours after the challenge. Prostaglandins and other eicosanoids are crucial mediators of innate immune responses. Eicosanoid biosynthesis is stimulated by infection in insects. Inhibition of eicosanoid biosynthesis lethally renders experimental insects unable to clear bacterial infection from hemolymph. Eicosanoids mediate specific cell actions, including phagocytosis, microaggregation, nodulation, hemocyte migration, hemocyte spreading and the release of prophenoloxidase from oenocytoids. Some invaders have evolved mechanisms to suppress insect immunity; a few of them suppress immunity by targeting the first step in the eicosanoid biosynthesis pathways, the enzyme phospholipase A2. We proposed research designed to cripple insect immunity as a technology to improve biological control of insects. We used dsRNA to silence insect genes encoding phospholipase A2, and thereby inhibited the nodulation reaction to infection. The purpose of this article is to place our view of applying dsRNA technologies into the context of eicosanoid actions in insect immunity. The long-term significance of research in this area lies in developing new pest management technologies to contribute to food security in a world with a rapidly growing human population. Full article
(This article belongs to the Special Issue Insect Immunity)
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Open AccessReview New Insights into Control of Arbovirus Replication and Spread by Insect RNA Interference Pathways
Insects 2012, 3(2), 511-531; doi:10.3390/insects3020511
Received: 1 April 2012 / Revised: 11 May 2012 / Accepted: 16 May 2012 / Published: 29 May 2012
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Abstract
Arthropod-borne (arbo) viruses are transmitted by vectors, such as mosquitoes, to susceptible vertebrates. Recent research has shown that arbovirus replication and spread in mosquitoes is not passively tolerated but induces host responses to control these pathogens. Small RNA-mediated host responses are key [...] Read more.
Arthropod-borne (arbo) viruses are transmitted by vectors, such as mosquitoes, to susceptible vertebrates. Recent research has shown that arbovirus replication and spread in mosquitoes is not passively tolerated but induces host responses to control these pathogens. Small RNA-mediated host responses are key players among these antiviral immune strategies. Studies into one such small RNA-mediated antiviral response, the exogenous RNA interference (RNAi) pathway, have generated a wealth of information on the functions of this mechanism and the enzymes which mediate antiviral activities. However, other small RNA-mediated host responses may also be involved in modulating antiviral activity. The aim of this review is to summarize recent research into the nature of small RNA-mediated antiviral responses in mosquitoes and to discuss future directions for this relatively new area of research. Full article
(This article belongs to the Special Issue Insect Immunity)
Open AccessReview Endosymbiont Tolerance and Control within Insect Hosts
Insects 2012, 3(2), 553-572; doi:10.3390/insects3020553
Received: 21 April 2012 / Revised: 31 May 2012 / Accepted: 5 June 2012 / Published: 15 June 2012
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Abstract
Bacterial endosymbioses are very common in insects and can range from obligate to facultative as well as from mutualistic to pathogenic associations. Several recent studies provide new insight into how endosymbionts manage to establish chronic infections of their hosts without being eliminated [...] Read more.
Bacterial endosymbioses are very common in insects and can range from obligate to facultative as well as from mutualistic to pathogenic associations. Several recent studies provide new insight into how endosymbionts manage to establish chronic infections of their hosts without being eliminated by the host immune system. Endosymbiont tolerance may be achieved either by specific bacterial adaptations or by host measurements shielding bacteria from innate defense mechanisms. Nevertheless, insect hosts also need to sustain control mechanisms to prevent endosymbionts from unregulated proliferation. Emerging evidence indicates that in some cases the mutual adaptations of the two organisms may have led to the integration of the endosymbionts as a part of the host immune system. In fact, endosymbionts may provide protective traits against pathogens and predators and may even be required for the proper development of the host immune system during host ontogeny. This review gives an overview of current knowledge of molecular mechanisms ensuring maintenance of chronic infections with mutualistic endosymbionts and the impact of endosymbionts on host immune competence. Full article
(This article belongs to the Special Issue Insect Immunity)
Open AccessReview Influences of Plant Traits on Immune Responses of Specialist and Generalist Herbivores
Insects 2012, 3(2), 573-592; doi:10.3390/insects3020573
Received: 30 April 2012 / Revised: 25 May 2012 / Accepted: 13 June 2012 / Published: 19 June 2012
Cited by 9 | PDF Full-text (145 KB) | HTML Full-text | XML Full-text
Abstract
Specialist and generalist insect herbivore species often differ in how they respond to host plant traits, particularly defensive traits, and these responses can include weakened or strengthened immune responses to pathogens and parasites. Accurate methods to measure immune response in the presence [...] Read more.
Specialist and generalist insect herbivore species often differ in how they respond to host plant traits, particularly defensive traits, and these responses can include weakened or strengthened immune responses to pathogens and parasites. Accurate methods to measure immune response in the presence and absence of pathogens and parasites are necessary to determine whether susceptibility to these natural enemies is reduced or increased by host plant traits. Plant chemical traits are particularly important in that host plant metabolites may function as antioxidants beneficial to the immune response, or interfere with the immune response of both specialist and generalist herbivores. Specialist herbivores that are adapted to process and sometimes accumulate specific plant compounds may experience high metabolic demands that may decrease immune response, whereas the metabolic demands of generalist species differ due to more broad-substrate enzyme systems. However, the direct deleterious effects of plant compounds on generalist herbivores may weaken their immune responses. Further research in this area is important given that the ecological relevance of plant traits to herbivore immune responses is equally important in natural systems and agroecosystems, due to potential incompatibility of some host plant species and cultivars with biological control agents of herbivorous pests. Full article
(This article belongs to the Special Issue Insect Immunity)

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