Instar Larvae Research Articles

Biological Parameters and Feeding Potential of Micromus timidus Hagen (Neuroptera: Hemerobiidae) on Selected Aphid Species

In the present study, we investigated on the developmental biology, adult longevity and fecundity of Micromus timidus Hagen on Aphis craccivora (Koch), Aphis gossypii Glover, Rhopalosiphum maidis (Fitch) and Uroleucon compositae (Theobald) at room temperature (28±20C) and relative humidity of 70%. The study design followed was completely randomized design (CRD). The study was conducted with three replications with 10 larvae in each replication for biology studies and for adult parameters 3 replications with 10 pairs in each replication used. Shortest incubation period, II instar and III instar duration, total larval period, pre-pupal period, and egg to adult period of M. timidus were recorded on A. craccivora, shortest I instar duration was recorded on U. compositae and least pupal period on A. gossypii. The developmental periods for all trait were extended when fed on R. maidis. The reproductive traits viz., oviposition period and adult longevity (male and female) were maximum when M. timidus adults fed on A. gossypii, and the highest fecundity was recorded when fed on A. craccivora. Feeding potential in M. timidus increases progressively across successive instars, with III instar larvae exhibiting the highest aphid predation rate, and first instar larvae displaying the lowest feeding activity. The maximum feeding potential of the larva was noted on A. craccivora (142.47 ± 31.66), while, the adult feeding potential increased when it was given with A. gossypii (1335.10 ± 192.74).

Revision of the Aspistomella group of genera (Diptera: Ulidiidae: Pterocallinae: Lipsanini).

Twenty-three species of the genera Aspistomella Hendel, 1909, Polyteloptera Hendel, 1909, and Ulivellia Speiser, 1929 occurring in South America (Colombia, Peru, Bolivia, and Brazil) form a monophyletic lineage sharing certain combinations of plesiomorphies and apomorphies with similar larval biology. The name Aspistomella Hendel, 1909 is a new senior subjective synonym of Paraphyola Hendel, 1909. The group of genera is extended by the addition of six known species, Aspistomella angustifrons (Hendel, 1909) comb. nov., A. crucifera (Hendel, 1909) comb. nov., A. lobioptera Hendel, 1909, A. heteroptera Hendel, 1909, A. lunata (Hendel, 1909) comb. nov., Polyteloptera apotropa Hendel, 1909, and Ulivellia inversa Speiser, 1929, and 17 previously unknown species. Aspistomella duo Kovac, Kameneva & V.Korneyev, sp. nov., A. enderleini Kameneva & V.Korneyev, sp. nov., A. garleppi Kameneva & V.Korneyev, sp. nov., A. obliqua Kameneva, V.Korneyev & Savaris, sp. nov., A. pachitea Kameneva & V.Korneyev, sp. nov., A. quinquincisa Kameneva & V.Korneyev, sp. nov., A. sachavaca Smit & Kameneva, sp. nov., A. schnusei Kameneva & V.Korneyev, sp. nov., A. steyskali Kameneva & S.Korneyev, sp. nov., A. teresensis Araújo, V.Korneyev & Savaris, sp. nov., A. tres Kovac, Kameneva & V.Korneyev, sp. nov., Ulivellia amnoni Smit, sp. nov., U. arcuata Kovac & Kameneva, sp. nov., U. laetitiae Smit, sp. nov., U. pseudinsolita Kameneva & V. Korneyev sp. nov., and U. tenoris Kovac & Kameneva sp. nov. are described. A key to the genera and species is given. Among the Lipsanini, this group of genera is easily recognised by the combination of an enlarged, anteriorly produced epistome (lower part of the face) and a low clypeus (in the other lipsanine genera the clypeus is high and the epistome is not enlarged), which supports its monophyly, and the differentiated short parafrontal setulae and long and strong frontal and interfrontal setae, which is a synapomorphy of a larger monophyletic lineage that also includes Chaetopsis Loew, 1868 and related taxa, as well as Amethysa Macquart, 1835, Euphara Loew, 1868 and their relatives. As far as is known, most species of this larger lineage are associated with various Poaceae plants. The species included here in the Aspistomella group are also associated with neotropical tall grasses: bamboo (Guadua) and wild cane (Gynerium). Aspistomella and Ulivellia larvae inhabit water-filled internode cavities (= "bamboo phytotelmata") of living bamboo culms of Guadua angustifolia. Newly emerged larvae use tunnels made by lepidopteran borers (Crambidae caterpillars) to penetrate the hard bamboo walls. Aspistomella and Ulivellia larvae are saprophagous and adapted to an aquatic lifestyle. The last instar larvae jump easily and pupate in the soil. The external morphology, cuticular sensilla and cephalopharyngeal skeletons of the third instar larvae of five Aspistomella and Ulivellia species (one with unknown adult stage) were studied by light and scanning electron microscopy. The main features that allow the identification of larvae and puparia are the unique posterior spiracles and the structure of the abdominal creeping welts. The morphological characteristics of Aspistomella and Ulivellia larvae are compared with other Lipsanini and their feeding habits with other ulidiids. An identification key for Aspistomella and Ulivellia is given. The adaptations to life in bamboo phytotelmata found in both neotropical Aspistomella and Ulivellia and in oriental members of the closely related family Tephritidae are discussed.

Modeling the Bioenergetics and Life History Traits of Chironomus riparius-Consequences of Food Limitation.

Chironomids have a number of characteristics that make them a useful group for investigating the impact of environmental and chemical stressors on their life cycle stages. It is crucial to first understand sensitivities to environmental factors and provide a basis for interpreting the results of toxicity tests. We focused on Chironomus riparius-one of the most studied species in aquatic toxicity tests-to understand the changes during the larval stage under conditions of food abundance and limitation. We developed a model based on Dynamic Energy Budget (DEB) theory, a framework to capture the entire life cycle of an individual under varying food and temperature conditions. Available information from this study and the literature pointed out that the first three larval instars are immature and the fourth larval instar is mature, during which the organism saves, in two phases, energy for essential processes occurring during the subsequent non-feeding stages. The model can successfully predict the observed prolonged fourth instar duration under food limitation, the times of life history events (e.g., pupation and emergence), and egg production. This model has the potential to be integrated with toxicokinetic-toxicodynamic models to study the effects of toxicants on a variety of biological traits.

Cry1Ac toxin binding in the velvetbean caterpillar Anticarsia gemmatalis: study of midgut aminopeptidases N.

The velvetbean caterpillar Anticarsia gemmatalis is one of the main soybean defoliators in Brazil. Currently, the main biopesticide used to control insect pests worldwide is the bacteria Bacillus thuringiensis (Bt), which produces entomopathogenic Crystal toxins (Cry) that act in the midgut of susceptible insects, leading them to death. The mode of action of Cry toxins in the midgut involves binding to specific receptors present on the brush border of epithelial cells such as aminopeptidase N (APN), alkaline phosphatase (ALP), cadherin, and others. Mutations in these receptors, among other factors, may be involved in the development of resistance; identification of functional Cry receptors in the midgut of A. gemmatalis is crucial to develop effective strategies to overcome this possible scenario. This study's goal is to characterize APNs of A. gemmatalis and identify a receptor for Cry1Ac in the midgut. The interaction of Bt spores with the midgut epithelium was observed in situ by immunohistochemistry and total aminopeptidase activity was estimated in brush border membrane vesicle (BBMV) samples, presenting higher activity in challenged individuals than in control ones. Ten APN sequences were found in a A. gemmatalis' transcriptome and subjected to different in silico analysis, such as phylogenetic tree, multiple sequence alignment and identification of signal peptide, activity domains and GPI-anchor signal. BBMV proteins from 5th instar larvae were submitted to a ligand blotting using activated Cry1Ac toxin and a commercial anti-Cry polyclonal antibody; corresponding bands of proteins that showed binding to Cry toxin were excised from the SDS-PAGE gel and subjected to mass spectrometry analysis, which resulted in the identification of seven of those APNs. Quantitative PCR was realized to compare expression levels between individuals subjected to sublethal infection with Bt spores and control ones, presenting up- and downregulations upon Bt infection. From these results, we can infer that aminopeptidases N in A. gemmatalis could be involved in the mode of action of Cry toxins in its larval stage.

Cordyceps cateniannulata, a new potential strain for controlling Allantus luctifer from China.

Allantus luctifer is one of the most serious pests of buckwheat, with its larvae mainly damaging leaves during the seedling and flowering stages. Entomogenous fungi play a crucial role as biological regulators of arthropod populations in nature. In this paper, a newly isolated strain 19GZAl-1, was identified as Cordyceps. cateniannulata through the observetions of macroscopic and microscopic morphological features, and the results of rDNA- ITS sequence alignment and phylogenetic analysis. By comparing the efficacy of ten entomopathogenic fungal strains, including six strains of C. cateniannulata and four other Cordyceps species, against A. luctifer larvae, the new strain 19GZAl-1 exhibited the highest mortality rate. Mortality rates of A. luctifer larvae treated by spraying with the strain 19GZAl-1 increased as larval stage decreased, with first instar larvae showing the highest mortality rate of 85%. The appressorium from conidia invaded the larval body through areas with thin cuticle, such as larva pod base and internode folds, after which the hyphae grew rapidly, filling the haemocoel, and finally protruding from the integument upon melanization and decomposition of the intestinal wall cells. The results suggest that the strain 19GZAL-1 of C. cateniannulata has potential against A. luctifer larvae, which is significant for further study on the infection mechanism of C. cateniannulata on insects.

Studies On The Statistical Analysis And Impact Of Seasonal Temperature And Relative Humidity Variation On The Development Of A Flesh Fly Sarcophagadux(Thomson 1869)(Diptera Sarcophagidae)

Background: The fleshfly Sarcophaga dux (Diptera;Sarcophagidae) is found in Indian Sub continent is of limited forensic significance as its poorly known larval development relationship with temperature and relative humidity. Objective: The objective of this study was to determine the effect of the temperature and relative humidity in the larval development of this fly in two seasons, Summer and Rain, so that the results of this study may enabling the forensic use of this fly in the estimation of Post Mortem Interval(PMI). Material and Method: The present study was carried out in the outer premises of the Regional Forensic Science Laboratory Building, Jagdalpur, Bastardist,Chhattishgarh, India. The fresh meat of male goat was used for rearing of larvae. The effect of temperature and relative humidity on the larval developmental time of this fly in two seasons, Rainy and Summer were studied in normal condition. Statistical analysis of variance was performed and standard significance level of P<0.05 was taken as standard. Results: The results of this study shown that in Rainy season it was completed in 264 h (11 days) when the average temperature ranged from 21.8°C to 24.5°C and the average humidity ranged from 79.5% to 95.5% where as in Summer it was completed in 528 hrs (22 days), when the temperature ranged from 26.5°C to 35.1°C and the humidity ranged from 34% to 67.5%. The P value was found to be P<<.05 in Temperature variation; andP<<0.05 in Humidity variation in different stages(1st instar larvae, 2nd instar larvae, 3rd instar larvae, Prepupae, Pupae and Adult). Conclusion: In the present study we have found that fluctuating temperature and relative humidity of outer condition in two seasons, Rainy and Summer effect the life cycle duration of the fly from the larvi position up to adult eclosion and statistical analysis has proved it to significant rejecting null hypothesis. This data can be further used in the estimation of Post Mortem Interval (PMI) in Homicide and Suspicious cases of both human and wild life poaching death cases.

Biology, morphometric and integrative taxonomy of litchi fruit borer, Conopomorpha sinensis Bradley, 1986: A major pest of litchi (Litchi chinensis Sonn.)

Abstract Conopomorpha sinensis (Lepidoptera: Gracillariidae), commonly known as the litchi fruit borer, is a devastating pest of litchi, leading to substantial economic losses in fruit production. The present study was incepted to supplement updated information on biology, morphometrics, integrative taxonomy, and phylogenetic analysis of C. sinensis. The duration of developmental stages such as egg, larval, pre-pupal, pupal, male and female adult lasts for 3.45 ± 1.13, 11.10 ± 2.52, 2.05 ± 0.51, 5.85 ± 0.88, 5.55 ± 1.00, and 9.00 ± 1.12 days, respectively. The average fecundity was 33.10 ± 6.84 eggs/female. The head capsule width for five larval instars was 0.11 ± 0.01, 0.18 ± 0.02, 0.34 ± 0.01, 0.58 ± 0.04, and 0.64 ± 0.06 mm, respectively. Phylogenetic analysis revealed distinct species-groups formed by C. sinensis with other fruit borer species considered (C. cramerella, C. litchiella Bradley, and Thaumatotibia batrachopa (Meyrick)). Understanding the life cycle of C. sinensis and its correct identification is crucial for targeted pest control strategies. Traditional and molecular taxonomy assist in rapid and accurate species identification and understanding of the evolutionary relationships among Conopomorpha species.

Neurotoxicity, Cytotoxicity, and Genotoxicity of Phyto-radio Synthesized Selenium Nanoparticles in Culex pipiens Complex.

Effective mosquito management strategies are crucial to minimize the number of mosquito-borne diseases. Selenium nanoparticles (SeNPs) are promising in mosquito control because they are effective and eco-friendly rather than synthetic insecticides. The current study was conducted to evaluate the impact of SeNPs on the detoxification enzymes, acetylcholine esterase (AChE), glutathione S-transferase (GST), and α-carboxyl esterase (α-CarE), in larval instars of Culex pipiens complex at the LC50 concentration. In 3rd instar larvae treated with microwave-assisted selenium nanoparticles (SeNPs-MW) and gamma-assisted selenium nanoparticles (SeNPs-G), it was found that AChE activity was significantly inhibited. On the other hand, significant increases in GST and α-CarE activities were observed. Additionally, genotoxic and ultrastructure studies of midgut epithelial cells in 3rd instar larvae revealed DNA damage and cell lysis, including destruction of the cell membrane, microvilli, and nuclei. These findings suggest that SeNPs have an adverse effect on AChE gene expression, resulting in its downregulation. This downregulation can be attributed to the formation of reactive oxygen species induced by SeNPs that can modulate the host defense mechanism leading to apoptosis and subsequent larval mortality. The present study was the first to use phyto-microwave-assisted and gamma-assisted synthesis of SeNPs which provides an eco-friendly and cost-effective solution to reduce the risk of chemical insecticides. Furthermore, an integrated pest management program (IPM) using nanocides can be successfully developed for mosquito control.

Immature stages of Pleuronota rufosquamosa (Fairmaire, 1893) (Coleoptera: Scarabaeidae: Cetoniinae), with notes on its biology.

Pleuronota rufosquamosa (Fairmaire, 1893) is a little-known flower beetle from southern China and northern Vietnam, and due to taxonomic changes, the genus Pleuronota Kraatz, 1892 and the species became new records of China. Morphological characteristics of adults are redescribed. Descriptions of the 3rd instar larvae and pupae are also provided, and the morphological differences of the larvae are compared with four genera of the subtribe Taenioderina. All morphological structures are supplemented by photographs. The life history of P. rufosquamosa is briefly summarized based on field observation and artificial breeding.

Biological Control of Aedes aegypti Larvae using Sea Shell Powder

Background: The Aedes aegypti mosquito is a primary vector for several arboviral diseases, including dengue, Zika, chikungunya and yellow fever, posing significant public health challenges, especially in tropical and subtropical regions. Traditional chemical insecticides have been the mainstay for controlling Aedes aegypti populations, but their extensive use has led to the development of insecticide resistance, environmental pollution and adverse effects on non-target organisms. This study explores the potential of sea shell powder as a natural larvicide against Aedes aegypti larvae. Methods: Sea shell powder, derived from the calcified exoskeletons of marine mollusks, was tested for its larvicidal activity against fourth instar larvae of Ae. aegypti at concentrations ranging from 100 to 600 ppm. Result: The results demonstrated a concentration and time-dependent increase in larval mortality, with LC50 values of 407.01 ppm at 24 hours and 327.55 ppm at 48 hours. The findings suggest that sea shell powder could serve as an effective, environmentally sustainable alternative to chemical insecticides, offering advantages such as biodegradability, low cost and reduced risk of resistance development. This study supports the potential inclusion of sea shell powder in integrated mosquito management programs, particularly in areas with prevalent insecticide resistance.

Moringa olifera leave extracts yielded from irradiated and unirradiated seeds cause toxicity and induce dysregulation of enzymatic activities in fall armyworm, Spodoptera frugiperda (JE Smith, 1797) [Lepidoptera: Noctuidae]

The fall armyworm, Spodoptera frugiperda is the most distractive polyphagous noctuid pest in tropical and subtropical regions. The current study was designed to examine the insecticidal activity of the water extract of Moringa olifiera leaves cultivated from unirradiated and 40 Gy irradiated seeds. Also, the effect of the extract on some digestive enzymes activities was assayed. The results indicated that the extract produced from 40 Gy irradiated seeds was more effective than those of unirradiated one. As well as, leaves extract produced from cultivated irradiated and unirradiated seeds decrease lipase protease and amylase activities of 3rd instar larvae of S. frugiperda and the highest decrease was in larvae fed on leaves produced from irradiated cultivated seeds. Therefore, the water extract of M. olifiera leaves cultivated from 40 Gy irradiated seeds might be seen as an environmentally beneficial pest management method.

Combating Spodoptera frugiperda (Lepidoptera: Noctuidae) with Moringa-Synthesized Silica Nanoparticles and Its Combination with Some Insecticides.

The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), is a major agricultural pest known for developing resistance to insecticides. This study investigated a novel approach to manage FAW by silica nanoparticles (SiNPs) synthesized from eco-friendly leaf extract of Moringa oleifera Lam. (Moringaceae). This green synthesis method offers a sustainable and potentially safer alternative to traditional chemical processes. SiNP formation was confirmed by various techniques: UV-visible spectrophotometer, X-ray spectroscopy with energy-dispersive (EDX), scanning electron microscopy (SEM), and dynamic light scattering (DLS). The effectiveness of SiNPs alone and their combination with three common insecticides (emamectin benzoate, indoxacarb, and chlorpyrifos) were evaluated against third instar larvae of fall armyworm. While SiNPs after 24h by leaf dipping method recorded limited insecticidal activity (LC50 = 9947.59mg/L), it significantly enhanced the potency of all three insecticides. Combining SiNPs with emamectin benzoate resulted in the most dramatic increase in effectiveness compared to the insecticide alone with LC50 = 0.295mg/L and 0.42mg/L, respectively. This research suggests that moringa extract can be a valuable resource for the green synthesis of nanoparticles potentially useful in pest control. This approach could potentially reduce the amount of insecticide needed for effective pest control, leading to a more sustainable and environmentally friendly agricultural practice.

Phytochemical screening and toxicity assessment of compounds isolated from the leaves of Mangifera indica L. for the control of Spodoptera litura (Lepidoptera; Noctuidae)

This study aimed to analyze the phytochemical composition and antioxidative capabilities of mango leaves (Mangifera indica L., Nam Dok Mai), indigenous to Sa Kaeo Province, Thailand. Various solvents with differing polarities, including n-hexane, DCM, ethyl acetate, and MeOH, were utilized for leaf extraction. The findings revealed the existence of eight groups of phytochemical compounds: alkaloids, flavonoids, coumarins, saponins, tannins, terpenoids, steroids, and cardiac glycosides. The MeOH crude extract exhibited the highest concentration of total phenolic compounds at 409.88 ±0.02 mg GAE/g. Furthermore, the MeOH crude extract demonstrated the strongest antioxidant activity, with an IC50 value of 0.52 ±0.02 μg/ml, as determined by the DPPH method. High-performance liquid chromatography (HPLC) was employed to identify gallic acid and mangiferin in the MeOH crude extract. Laboratory tests were conducted using the topical application method to evaluate the toxicity of the M. indica leaf crude extract on 2nd instar Spodoptera litura larvae. The MeOH crude extract exhibited high efficacy, with an LD50 value of 10.58 µg per larvae within 24 hours. Gallic acid and mangiferin were identified as the primary active ingredients, with LCD50 values of 1.19 µg per larvae and 1.90 µg per larvae, respectively, within 24 hours. Additionally, the impact on detoxification enzymes (24 hours post-treatment) was assessed in surviving 2nd instar S. litura larvae using the topical application method. The MeOH extract treatment resulted in 1.31-fold inhibition of carboxylesterase (CE), 1.31-fold inhibition of glutathione-S-transferase (GST), and 1.32-fold inhibition of acetylcholinesterase (AChE).

Effect of temperature and soil moisture on the infectivity of four species of entomopathogenic nematodes (Steinernema and Heterorhabditis spp.) to fall armyworm, Spodoptera frugiperda (Smith)

Spodoptera frugiperda (JE Smith) is one of the most important lepidopterous pests of maize throughout the word. The implementation of management strategies for this are need of the hour. In this case the use of Entomopathogenic nematodes (EPNs) is feasible because third-instar larvae feed in the leaf whorls of maize, and sixth instar larvae pupate in the soil; these two environments are congenial for the EPNs. But temperature and soil moisture play major roles in EPNs infectivity. Therefore, in the current study, we examined temperature and soil moisture effect on the infectivity of four indigenous EPN species from India, Heterorhabditis indica NBAIIH23, H. bacteriophora NBAIRH75, Steinernema carpocapsae NBAIRS59, and S. abbasi NBAIISa01 against larvae and pupae of S. frugiperda. Present study results showed that both temperature and soil moisture affected the infectivity of H. indica, S. carpocapsae, H. bacteriophora, and S. abbasi. As the exposure time increased, all these four nematodes infectivity to larvae was increased. Six days after inoculation, H. indica caused significantly higher larval mortality (96 %) at 25 °C and 100 % mortality at 28 °C. Whereas, S. carpocapsae caused 100 % mortality at 28 °C, and 76 % mortality at 25 °C. At 32 °C, H. indica and S. carpocapsae caused 90 % and 92 % larval mortality, respectively. As the temperature decreased to 20 °C, the infectivity of both the nematodes decreased. However, H. bacteriophora and S. abbasi caused 68 % and 50 % mortality in larvae at 20 °C, respectively. Compared to other nematodes, H. indica significantly caused higher mortality in pupae at 13 % soil moisture at 28 °C. We conclude that, Heterorhabditis indica and S. carpocapsae can be utilized against S. frugiperda larvae at (25–32 °C), and pupae at (28 °C). These nematodes can also be used against pupae of S. frugiperda at 9–13 % soil moisture content. We also suggest that these EPNs species can be incorporated in the Integrated Pest Management (IPM) for S. frugiperda.

Assessing the potential of native copepods in Guatemala for Aedes vector control.

In this study we examine the feeding efficiency of copepods locally found in Guatemala on first instar Aedes aegypti larvae. Copepods are a potential tool for Aedes vector control that has shown promising results in the laboratory and in community-based field trials. Four different copepod species from different habitat types were included in the laboratory assays of this study. All four tested copepod species decreased the number of the first instar Aedes larvae that were inserted into the glass vessels compared with controls. However, average predation rates between the tested species were highly different, with Thermocyclops crassus and Mesocyclops longisetus achieving the highest, with 31.0% (standard deviation [SD] 18.9) and 28. 9% (SD 11.2), respectively. The copepod species with identified high predation rates are potential candidates for planned and other future field trials for community-based Aedes vector control with copepods in the region.

Comparison of distinct gut bacterial communities in different stage of prediapause and nondiapause larvae in Loxostege sticticalis.

Symbiotic microorganisms in insects regulate multiple physiological functions, widely participating in nutrient metabolism, immune regulation, and crucial regulatory roles in development. However, little is known about how microbial factors might respond to the preparation of insect diapause. The gut bacterial communities of Loxostege sticticalis larvae induced at different photoperiod of long (LD16:8, nondiapause) and short (LD12:12, prediapause) daylength were compared, by 16S rRNA Illumina MiSeq. A total number of 42 phylum, 78 classes, 191 orders, 286 families, 495 genera, and 424 species were identified in the intestinal bacterial community of L. sticticalis larvae. Alpha diversity and beta diversity analyses revealed significant differences between nondiapause and prediapause larvae. In non-diapause larvae, the dominant intestinal bacteria were Firmicutes and Proteobacteria. In specific, in 3rd and 4th instar larvae, the main intestinal bacteria were Staphylococcus, while in 5th instar, it was JC017. For the prediapause larvae, the dominant phylum in 3rd instar larvae was Firmicutes, with the dominant genus of Staphylococcus, while in 4th and 5th instar larvae was Bacteroidota, with the dominant genus 4th instar was Staphylococcus, and in 5th instar was JC017. KEGG functional prediction analysis revealed that functional bacterial groups involved in metabolism had the highest abundance values. Specifically, the amino acid metabolism of metabolism-related functional genes in the 3rd instar prediapause larvae was significantly lower than that in the 4th and 5th instar prediapause larvae and the non-diapause treatment. However, the carbohydrate metabolism in 3rd instar prediapause larvae was significantly higher than that in 4th and 5th instar prediapause larvae and non-diapause treatments. The dominant bacterial phylum in the prediapause larvae at different stages of L. sticticalis was varied, and there were significant differences in community diversity and richness. These results suggest a complex interaction between the hosts' physiological state and its gut microbiota, indicating that bacterial communities may assist insects in adapting to diapause preparation by regulating their metabolic levels. This study lays the foundation for further understanding the physiological mechanisms by which intestinal microorganisms regulate overwintering dormancy in the L. sticticalis.

Toxicological effects and defense mechanisms induced by beta-cypermethrin in Drosophila melanogaster

Widespread use of the pyrethroid insecticide beta-cypermethrin (beta-CYP) has led to adverse effects on nontarget populations within agroecosystems. Despite the efficacy of beta-CYP in pest control, its toxicological and defense mechanisms remain incompletely understood. In the present study, we explored the toxicological effects, antioxidant mechanisms and immune response against beta-CYP using Drosophila melanogaster, a well-established model organism for the study of insect biology, to represent the broader class of nontarget organisms. We exposed Drosophila larvae to 0.667 μg/mL beta-CYP and revealed that delayed development and caused intestinal epithelial damage in larvae. To gain insights into the molecular underpinnings of these effects, RNA sequencing analysis and quantitative polymerase chain reaction validation were performed. These analyses revealed that the messenger RNA levels of glutathione S-transferase were increased, third instar larvae exhibited an increase in reactive oxygen species content and a corresponding increase in antioxidant enzyme activity in response to beta-CYP exposure, indicating an upregulated response to oxidative stress. Beta-CYP also activated Hippo pathway to resist apoptosis and promote cell proliferation. Moreover, beta-CYP induced melanization and Toll immune pathways involved in immune response in Drosophila larvae, specifically the Toll pathway gene Drs. This activation suggests that Drosophila increases antioxidant defenses and promotes mitosis in damaged tissues as compensatory mechanisms to mitigate the cytotoxic effects of beta-CYP. These findings provide new insight into the mechanisms of beta-CYP–induced toxicity and the defense mechanisms in insects; they may also inform strategies for the sustainable use of insecticides and the development of mitigation measures to protect nontarget species in agroecosystems.

Description of immature stages of Hybosa acutangula Spaeth, 1913 (Coleoptera, Chrysomelidae, Cassidinae).

The immature stages of Hybosa acutangula Spaeth, 1913, member of the tribe Cassidini Gyllenhal, 1813, are described in detail and compared with other members of Cassidini and Ischyrosonychini Chapuis, 1875 species. The eggs, oothecae and first instar larvae are described for the first time. The morphology of the immatures of H. acutangula, unusual for the species of the Cassidini tribe, was the impulse that initiated the research. The result of the comparative analysis is the conclusion that the morphological features of the immature stages of H. acutangula are a mixture of characters observed in representatives of the Cassidini and Ischyrosonychini tribes. The similarity to Ischyrosonychini may only be convergence, but it cannot be ruled out that there is a separate phylogenetic lineage within Cassidini, represented by H. acutangula. Verification of this hypothesis requires further research.

Adaptation and carry over effects of extreme sporadic heat stress in Culex mosquitoes

Mosquitoes, as temperature-sensitive ectothermic vectors, exhibit temperature-dependence. This study investigates Culex pipiens pallens (Cx. pallens) responses to abrupt temperature increases and their implications on mosquito physiology.First instar larvae (24hr post hatching) and newly enclosed adults (24hr post emergence) were separately exposed to heat shock regimes of 33 °C, 37 °C, and 42 °C for 3 days alongside a control temperature of 27 °C. Results showed that mortality was triggered at 42 °C within a day. Adult male mosquitoes were less tolerant to all temperatures than larvae and adult females (p < 0.05). Exposing larvae to constant temperatures for 3 days significantly decreased larvae's development time, growth rate and adult emergence (p < 0.05). Reproductive fitness was significantly reduced (p < 0.05) in males emerging from larvae exposed to 37 °C. Life table parameters showed significant increased mortality rate, kill power and decreased life expectancy at the embryonic stage (p < 0.05). Furthermore, heatwaves deactivated the Transient receptor protein ankyrin 1 at 37 °C (p < 0.05) in larvae but not adults. Calmodium, Heat shock protein 90, and small heat shock protein expression were significantly decreased in larvae at 37 °C (p < 0.05) as compared to larvae raised at 33 °C and 27 °C.In conclusion, we classified the heat waves into three categories: adaptable (33 °C), critical (37 °C), and fatal (42 °C). Prolonged exposure of Culex pallens larvae to extreme heat affects the male reproductive output. These findings may serve as an important reference for forecasting vector and pest dynamics and used to tailor mosquito prevention and control measures.

Application timing affects the efficacy of Bacillus thuringiensis subsp. kurstaki against Tortrix viridana in deciduous oak forests

The green oak leaf roller moth, Tortrix viridana, is one of the main defoliators of deciduous oaks in the Mediterranean region. Although aerial applications of Btk-based insecticides represent the most effective method to control the larval populations of this pest at a large spatial scale, the optimal time window for sprayings has not yet been defined. Accordingly, experimental trials were conducted in a Quercus pubescens forest district in Sardinia (Italy) involving both large-scale aerial treatments and small-scale applications from the ground. The aim of our work was to study how different larval development stages and/or sprouting phenological phases of the host trees affect Btk efficacy. Aerial sprayings were conducted in 2003 and 2004 in two different areas of about 300 ha, selected according to altitude and exposure to simulate three different application timings against different larval instars and sprouting phenological phases. From-the-ground applications were carried out in 2021 in a Q. pubescens forest stand by applying Btk-based insecticides at different timings, and the overall Q. pubescens phenological stage and the distribution of T. viridana larval development stages were assessed accordingly. The effectiveness of Btk applications was evaluated by estimating larval mortality 7, and 14 days after aerial applications, and 7, 14 and 21 days after ground applications. Defoliation due to T. viridana was also evaluated at the end of larval development in all years. In both 2003 and 2004, the average larval mortality due to Btk exceeded 80 % two weeks after aerial applications across all application timings. Damage caused by T. viridana varied with Btk application timing, with the later applications showing a higher defoliation than other timings. In ground application experiments, larval mortality significantly increased when Btk was sprayed against a larval population primarily composed of IV instars, which were feeding on sprouts with leaves that were spread out and had not fully developed internodes, thus resulting in a significative reduction of insect damage. Our findings indicate that, in accordance with the strict synchrony between the larval development and the oak flushing, the optimal timing for Btk application against T. viridana can be defined based on the bud burst phenological phase. In particular, the prevalence of sprout with expanding leaf surface allowing insecticidal droplet interception and the simultaneous presence of susceptible larval instars (within the IV), resulted in an increased treatment efficacy.