Search Results (781)

Tetranychus mexicanus (McGregor, 1950) (Tetranychidae) is considered one of the primary phytosanitary problems in passion fruit crops, resulting in significant production losses. Understanding the impact of this mite species’ activity on the physiology of passion fruit plants can serve as a basis for developing sustainable management strategies. With this in mind, this research sought to analyze, using supervised and unsupervised machine learning models, how T. mexicanus mite infestation influences gas exchange, chlorophyll “a” and chlorophyll “b” levels, fluorescence, and thermal response of passion fruit plants. We tested the hypothesis that juvenile and adult mites alter the physiological and thermal response patterns of plants. Only the variables related to the fluorescent response (Fo, Fm, and Fv) had a significant relationship with mite infestation. In the joint comparison of multiple fluorescent variables, there were differences between the treatments of plants infested and not infested by T. mexicanus. The variables’ initial fluorescence (Fo), maximum fluorescence (Fm), and variable fluorescence (Fv) of chlorophyll a had a direct negative impact on both reproductive activity, as measured by the number of eggs and nymphs produced, and the total number of mites found. The unsupervised model based on multidimensional scaling with the k-means algorithm revealed a clear separation between the groups of infested passion fruit plants (Group 1) and healthy plants (Group 2). The Fo response was described with high accuracy for the reproductive rate (75%) and total infestation of eggs, nymphs, and adults of the mites (99.99%). Kappa values were moderate (Kappa = 0.50) and high (Kappa = 0.99) for reproductive and total rates of T. mexicanus, respectively. Additionally, the thermal response revealed that the infested passion fruit plants had a median temperature of 25.1 °C, compared to a median temperature of 25.7 °C, with notable differences between these medians. Therefore, the T. mexicanus mite altered both the fluorescent and thermal patterns of passion fruit plants. Our findings have implications for the development of early detection tools and the generation of future resistance breeding. Full article

The physiological and gill health responses of juvenile spotted rose snapper (Lutjanus guttatus) were evaluated at four salinities—8, 16, 24, and 32‰—over a 70-day period. Fish reared at 8‰ exhibited the highest final body weight (126.8 ± 2.6 g), which was significantly higher than their congeners kept at 24‰ (116.0 ± 2.3 g) and 32‰ (116.0 ± 2.3 g). This superior growth at 8‰ coincides with the complete absence of parasitic monogenean infestations. In contrast, parasite prevalence increased with salinity, reaching 87.5% at 24‰, and was associated with gill pathologies like hyperplasia. Plasma osmolality and chloride levels decreased at lower salinities, while sodium and potassium levels showed a compensatory increase. Plasma cortisol and glucose levels remained stable across all treatments, indicating an absence of chronic stress. These findings suggest that the optimal rearing salinity for juvenile L. guttatus is near 8‰. The enhanced growth at this salinity appears to be the result of a net energy gain, stemming from a trade-off between the minor cost of osmoregulation in a hypo-osmotic environment and the major energetic benefit of avoiding parasitic disease. Full article

Silicon (Si) is gaining recognition as a sustainable alternative to reduce insecticide use in the management of the Asian citrus psyllid and huanglongbing (HLB). This study aimed to evaluate the effects of two silicon sources and three application methods on Diaphorina citri incidence, soil chemical properties, and foliar nutrient uptake in a Tahiti lime orchard. Using a randomized block design, treatments were applied six times over three months. Foliar and combined applications of diatomaceous earth reduced vegetative flushing and decreased natural psyllid incidence by up to 75% in the first 30 days. While silicon did not affect oviposition in induced infestations, it disrupted the nymph-to-adult transition. Silicon also improved soil conditions, increasing pH, organic matter, and the availability of phosphorus, calcium, and magnesium. In leaf tissue, higher levels of nitrogen, phosphorus, potassium, iron, and silicon (0.28–0.50%) were observed. Fruit quality improved with silicon, showing greater fresh weight (134 g) and juice content (44.7%) compared to the control (95.33 g and 28.5%). The results suggest that silicon’s effectiveness depends more on its availability and application method than its source. Incorporating silicon, especially diatomaceous earth, into fertilization programs supports pest control, enhances soil and plant nutrition, and improves fruit quality. Full article

Argasid ticks Ornithodoros erraticus and Ornithodoros moubata are major vectors of zoonotic pathogens, including the African swine fever virus and relapsing fever Borrelia spp., and their control is essential to reduce disease transmission. In this study, we evaluated the immunogenicity and protective efficacy of four Ornithodoros tick antigens formulated as mRNA–lipid nanoparticles (mRNA-LNPs): OeSOD, OeTSP1, OmPLA2, and Om86. Rabbits were immunised with three doses of each mRNA-LNP construct, and immune responses and tick biological parameters were assessed following infestation with both tick species. All mRNA-LNP constructs induced antigen-specific IgG responses that recognised native proteins in tick saliva and midgut extracts. Vaccination resulted in significant reductions in female oviposition and fertility, which correlated with antibody levels, and yielded protective efficacies of 21.9–41.6% against O. moubata and 23.1–41.6% against O. erraticus. Notably, the mRNA-LNPs of OeSOD and OeTSP1 outperformed their recombinant counterparts against O. moubata, and Om86 mRNA-LNP conferred markedly improved protection against both O. moubata and O. erraticus. These findings highlight the potential of mRNA-LNP vaccines to induce effective anti-argasid tick immunity and provide a promising platform for the development of sustainable strategies to control argasid ticks and associated pathogens. Full article

Drought-tolerant cactus Opuntia stricta sustains livestock in Brazil’s semi-arid Northeast but suffers yield losses from the armored scale insect Diaspis echinocacti. Symbiotic bacteria are thought to underpin scale fitness; however, their response to pest pressure remains unexplored. We characterized the bacterial communities of D. echinocacti collected from cladodes displaying low, intermediate, and high infestation (n = 3 replicates per level) using 16S-rRNA amplicon sequencing, processed with nf-core/ampliseq. Shannon diversity declined from low to high density, and Bray–Curtis ordination suggested compositional shifts, although group differences were not significant (Kruskal–Wallis and PERMANOVA, p > 0.05). The obligate endosymbiont “Candidatus Uzinura” dominated all samples (>85% relative abundance) irrespective of density, indicating a resilient core microbiome. PICRUSt2 predicted a contraction of metabolic breadth at higher infestations, with convergence on energy- and amino acid biosynthesis pathways. Taken together, increasing pest density was associated with modest loss of diversity and functional streamlining, rather than wholesale turnover. These baseline data can guide future work on microbiome-based strategies to complement existing scale-insect control in dryland cactus systems. Full article

The use of unmanned aerial vehicles (UAVs) in agricultural pest management has emerged as a promising alternative to conventional methods, particularly in challenging terrains. This study assessed the effectiveness of UAV-based versus ground-based bait spraying for controlling the olive fruit fly Bactrocera oleae in four regions in Greece (Larisa, Zakynthos, Trifillia, and Crete) over a four-year period (2021–2024). In each region, three olive orchards were selected: one received UAV-based bait applications, one was treated using standard ground-based bait application, and the third served as an untreated control. UAV applications were conducted using the M6E hexacopter, while ground treatments followed conventional protocols. Infestation levels were evaluated through systematic fruit sampling, assessing both overall and active infestations. Climatic and orchard data were also recorded to interpret variability in treatment outcomes. Results showed that both UAV and ground treatments significantly reduced infestation compared to the control. Active infestation ranged from 14.2–22.5% in control-untreated plots, 4.6–7.8% in UAV plots, and 5.3–8.4% in ground-treated plots. A significant year × treatment interaction indicated variable efficacy across years, with clearer treatment effects in 2021–2022. UAV applications were as effective or superior to ground spraying, especially in hard-to-reach areas. These findings support the integration of UAVs into pest management programs as a sustainable and efficient alternative for olive fly control. Full article

Tick infestation represents a significant constraint on livestock productivity in Saudi Arabia; however, there remains a substantial gap in research addressing tick species diversity, distribution, and their direct effects on milk production. This study aimed to morphologically and molecularly identify tick species infesting dairy cattle, quantify the impact of tick infestation on milk yield and composition, and contribute to the limited understanding of tick ecology and its economic implications in the region. Ticks were collected from infested cows and identified morphologically using taxonomic keys. Molecular identification was performed via PCR amplification of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Milk production and quality parameters were assessed in tick-infested and healthy cows in Hafar Al-Batin, Eastern Saudi Arabia. Morphological and genetic analyses confirmed Hyalomma anatolicum as the predominant tick species in the study area, with COI sequences showing high similarity to regional isolates. Tick-infested cows exhibited substantial reductions in milk yield, fat, calcium, and potassium levels, indicating significant metabolic disruptions. Blood biochemical analysis revealed elevated levels of liver enzymes [aspartate aminotransferase (AST) increased by 238.6%, gamma-glutamyl transferase (GGT) by 155.7%], renal markers [creatinine increased by 788.9%, urea by 130.0%], and electrolyte imbalances [serum calcium decreased by 39.5%, potassium by 45.2%]. Hematological findings included increased white blood cell (WBC) and red blood cell (RBC) counts by 44.9% and 124.7%, respectively, along with a 53.1% decrease in hemoglobin (HGB), suggesting a systemic inflammatory response and possible anemia. This study is among the first to genetically confirm the presence of H. anatolicum in Hafar Al-Batin using molecular tools, thereby enhancing the accuracy of species-level identification and highlighting the physiological impact of tick burden on dairy productivity. Full article

Millet (Pennisetum glaucum (L.) R. Br.) is the most widely consumed cereal in Niger. Although its production lasts six months, consumption is year-round, requiring effective and safe storage solutions. Post-harvest losses of millet can reach up to 17% after several months of storage. Chemical pesticides are commonly used in large warehouses, but concerns over misuse and health risks have driven interest in safer alternatives. This study assessed the effectiveness of traditional and improved storage methods in controlling Trogoderma granarium Everts, an emerging pest of millet in large warehouse facilities. Three storage methods were tested: (i) a hermetic Purdue Improved Crop Storage (PICS) bag; (ii) chemical pesticide Phostoxin; and (iii) an untreated ordinary polypropylene bag as a control. Naturally infested millet obtained from a large warehouse was assessed for each treatment at the start and end of a six-month storage period. Two insect pests were identified, T. granarium and Tribolium sp. Initial infestation levels were 60 larvae and 0.47 adults per 500 g. After six months, the control showed a 1.7-fold increase in T. granarium larvae, a 2.96-fold increase in its adults, and a 3.19-fold increase in Tribolium sp. adults, resulting in 19.15% weight loss. In contrast, PICS and Phostoxin treatments maintained initial pest levels with no weight loss. These results suggest that hermetic storage is a safe, effective, and chemical-free alternative for preserving millet in large warehouses. Full article

Soybean cyst nematode (SCN) is a pathogen with serious impacts on soybean yields, yet traditional field-based assessment is labor-intensive and often ineffective for early interventions, and the existing spectral vegetation indices (VIs) also lack the ability to accurately detect SCN infested plants. This study aimed to develop an improved detection method using hyperspectral data. A greenhouse-based experiment was designed to collect 100 hyperspectral datasets from 20 soybean plants inoculated with four SCN egg levels (0–10,000) from the 68th to 97th day after planting. Based on spectral similarity and inoculation levels, three stress classes were defined as proxies for actual plant stress: healthy (0 egg), moderate (1000 and 5000 eggs), and severe (10,000 eggs). These classifications are based on predefined inoculation thresholds and spectral trends, which may not fully align with direct physiological stress measurements due to inherent variability in individual plant responses. Through analysis of variance (ANOVA), principal component analysis (PCA), feature selection, and classification comparison, a new spectral VI, called SCNVI, was proposed using bands 338 nm and 665 nm. The SCNVI coupled with eXtreme Gradient Boosting (XGBoost) achieved an accurate classification of 70% for three classes and outperformed the 12 traditional VIs. These findings suggest that integrating the SCNVI and XGBoost algorithm provides the potential for improving the detection of SCN infestation, though further validation in field environments is required to confirm its practical applicability. Full article

Rhododendron spp., valuable ornamental plants, frequently suffer from infestations of the azalea lace bug (Stephanitis pyrioides Scott, ALB). However, the hormonal regulatory mechanisms underlying Rhododendron defense against ALB are not well understood. In this study, integrated transcriptomic and metabolomic analyses were performed to investigate the phytohormone responses under ALB stress in two Rhododendron cultivars with distinct insect susceptibility: the resistant ‘Taile’ (TL), and the susceptible ‘Yanzhimi’ (YZM). Transcriptomic sequencing identified 10,052 and 3113 differentially expressed genes (DEGs) in ‘TL’ and ‘YZM’, respectively, after ALB infestation. KEGG pathway enrichment analysis revealed that the DEGs in ‘TL’ were significantly enriched in hormone signal transduction pathways, including gibberellin (GA), jasmonic acid (JA), salicylic acid (SA), and ethylene (ETH), with 21 out of 25 hormone-related DEGs being upregulated. In contrast, ‘YZM’ exhibited 18 upregulated and 13 downregulated DEGs and suppressed auxin and cytokinin signaling. Non-targeted metabolomic analysis detected increased indole-3-acetic acid (IAA), abscisic acid (ABA), and jasmonoyl–isoleucine (JA-Ile) levels in both cultivars. ‘TL’ also showed elevated levels of SA precursor (benzoic acid) and ethylene precursor (1-aminocyclopropane-1-carboxylate, ACC). These findings indicate that ALB infestation induces endogenous hormone signaling-related genes in Rhododendron leaves and regulates hormones such as SA and JA to counteract insect stress. This study provides theoretical insights into the molecular mechanisms of Rhododendron defense against insect herbivory and lays the foundation for breeding resistant cultivars. Full article

The aphid, Aphis gossypii Glover, and the leaf beetle, Lema decempunctata Gebler, are two catastrophic pests affecting the production of the organic goji berry, Lycium barbarum L. Our previous studies have demonstrated that the defense responses of goji berry induced by aphid infestations can facilitate the growth and development of beetles. However, the reciprocal effects of these two insect infestations on aphids remained unclear. In this study, the impacts of these two pest infestations on the development, survival, and reproduction of aphids were examined. Additionally, the levels of plant defense-related hormones, salicylic acid (SA) and jasmonic acid (JA), were measured. Subsequently, host plants were treated with two hormone analogues, 2, 1, 3-benzothiadiazole (BTH) and methyl jasmonate (Me-JA), to identify their effects on aphid development, survival, and reproduction. The results showed that the total developmental duration was accelerated by 33.60%, and the total reproduction of aphids was increased by 82.98% compared to the control after aphid infestation, without influencing survival. In contrast, the beetle infestation did not significantly influence any aspect of the aphid population. The content of SA in plants after the aphid infestation and JA after the beetle infestation increased 19.42 times and 400.50 times, respectively, compared with the control. The total developmental duration of aphids treated with BTH was reduced by 13.44%, while their reproduction increased by 60.52% compared with the control. The total developmental duration of aphids treated with Me-JA was prolonged by 23.51% compared to the control, while survival rates and reproduction were unchanged. Our research elucidates the intricate interspecific relationship between A. gossypii and L. decempunctata, providing valuable insights into the complex interspecific relationship between the two pests and informing effective strategies for their scientific prevention and control. Full article

Since there are no available vaccines against some arboviruses, vector control is the most effective way to reduce their incidence. In this context, mechanical control is one of the most cost-effective ways to suppress Aedes populations, but it requires knowledge about vector breeding ecology in varied landscapes and climates. Here we investigated the infestation levels and container types used as larval habitats by Aedes aegypti and Aedes albopictus in an urban gradient of Vassouras, a countryside city in Rio de Janeiro. Larval surveys were conducted bimonthly from January 2017 to December 2018. Infestation was measured through the House (HI) and Breteau indexes (BI). Container types found with Aedes spp. immatures were correlated with temperature and rainfall and were compared between urbanization zones. The distribution of positive containers was mapped. The HI for Ae. aegypti increased during rainy seasons, but the HI and BI were always <1% for both mosquito vectors. More reservoirs were found harboring Ae. albopictus than Ae. aegypti, but in general their relative distribution into types was similar between species. On the other hand, the amount and distribution of containers into types varied across urbanization zones. Finally, the spatial distribution of larval habitats was similar between species, as well as often constant between seasons and study years. Full article

Witches’ broom disease of blue palo verde (Parkinsonia florida) was reported more than sixty years ago. Characteristic symptoms consist of dense clusters of shortened, brittle branches and stunted leaves. The suspect causal agent has been identified as palo verde broom virus (PVBV), genus, Emaravirus, family, Fimoviridae. Here, the first complete PVBV genome sequence was determined, and virus small interfering RNAs (vsiRNAs), primary metabolites, and phytohormone profiles were characterized from infected palo verde leaves, adventitious shoots, flowers, and seeds. Based on pairwise distances, PVBV RNAs 1–4 shared 54–65% nucleotide identity and 19–51% amino acid similarity, respectively, with other emaraviruses, while PVBV RNA 5 shared no sequence homology with any emaravirus. The 21–24-nt virus-derived vsiRNAs, indicative of post-transcriptional gene silencing (PTGS), represented nearly the entire PVBV genome in flowers, leaves, seeds, and adventitious shoots; however, PVBV RNA 3 and RNA 4 were most heavily targeted in all plant parts. Evidence that six major phytohormones were altered in PVBV-infected compared to virus-free trees indicated that emaravirus-infected trees mount classical defense responses to virus infection and/or eriophyid mite infestations. Detection of PVBV RNA genome segments 1–5, accumulation of predominantly 21-nt vsiRNAs, homologous to the PVBV genome and transcripts, and altered levels of phytohormones and metabolites in PVBV-infected trees strongly implicate PVBV as the causal agent of witches’ broom disease. Full article

This study, which began in the 2013/2014 agricultural year, aimed to assess the suitability of two soil tillage systems for wheat cultivation: conventional soil tillage (CS), which involved moldboard plowing to a depth of 28 cm followed by a single pass with a rotary harrow to prepare the seedbed, and no-tillage (NT). It also sought to analyze the impacts of these systems on weed infestation levels and, consequently, on yield. A moderate level of fertilization was applied. The experimental field was established with a three-year crop rotation system: soybean–winter wheat–maize. The total number of weed species was 30 in CS, the representative species being Xanthium strumarium, and in NT there were 29 species, with Xanthium strumarium, Cirsium arvense, Bromus tectorum, and Agropyron repens predominating. There was an increase in the number of perennials (dicots and monocots). The total dry matter of weeds was 35.4 t ha⁻¹ in CS and 38.8 t ha⁻¹ in NT. After 11 agricultural years, it was found that there were no significant differences between the two soil tillage systems in terms of wheat yield (6.55 t ha⁻¹ in CS and 6.46 t ha⁻¹ in NT). The uneven rainfall negatively affected wheat growth and favored the spread of weeds, especially dicotyledonous ones. Full article

Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) is a major insect pest that severely affects various crops. Our study provides new insights by combining field efficacy trials with enzymatic analysis to evaluate the effects of emamectin benzoate mixtures with other insecticides (lufenuron, cypermethrin, chlorpyrifos, and spinosad) against S. littoralis. The aim of our work was to investigate the effectiveness of five insecticides, i.e., emamectin benzoate, lufenuron, cypermethrin, chlorpyrifos, and spinosad, for controlling this pest under field conditions during two consecutive seasons (2023–2024). Each insecticide was applied individually at the recommended rate, while some were mixed with emamectin benzoate at half its recommended rate. The results indicated that emamectin benzoate was the most effective insecticide, followed by lufenuron. The joint action of emamectin benzoate (LC₂₅) and its mixtures with other insecticides (chlorpyrifos, spinosad, cypermethrin, and lufenuron) at various concentrations (LC₅₀) against second- and fourth-instar S. littoralis larvae was evaluated. Results showed additive effects with chlorpyrifos, lufenuron, and cypermethrin, while potentiation occurred with cypermethrin (LC₅₀) and chlorpyrifos (LC₅₀). Antagonistic effects were observed in the combination of emamectin benzoate with spinosad (LC₂₅ and LC₅₀). This study concluded that applying insecticides individually is more cost-effective for managing cotton leafworm infestations in cotton crops. Additionally, enzyme activity analysis showed significant changes in alpha-esterase, beta-esterase, carboxylesterase, acetylcholinesterase, and glutathione S-transferase levels in larvae treated with different insecticide combinations. Full article