4th Instar Larvae Research Articles

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.

Efficacy and Residual Analysis of Three Insecticides against Spodoptera littoralis (Boisd.) on Field-grown Tomatoes

Spodoptera littoralis (Boisd.) is among the most destructive insect pests in Egypt, the field study was conducted at El-Beheira Governorate, Egypt to evaluate the toxicity of three insecticides against 2nd and 4th larval instars of these insect and residual effect in tomato fruit into open field application. The outcomes demonstrated that spinosad, methoxyfenzide and diflubenzuron proved to be very toxic. Semi-field application showed that spinosad was the most effective with 91.38 % and 100% insect pest mortalities at initial and residual effects against second instar larvae, respectively. The initial effect manifested higher morality (90.25%) for fourth instar larvae when treated with diflubenzuron followed by spinosad (86.50%), then methoxyfenzide (84.25%), while the residual effects of all tested insecticides were 100% mortality. The findings additionally demonstrated that the pre-harvest intervals (PHI) for diflubenzuron, spinosad, and methoxyfenzide were 3,7 and 10 days, respectively, for tomato fruits. Following this PHI, the products are considered safe for export and local consumption, as the residue level satisfies the maximum residue limit, which is the level documented by the European Union.

Predatory potential of Coccinella undecimpunctata L. (Coleoptera, Coccinellidae) on Aphis craccivora Koch. (Hemiptera, Aphididae) in Ladakh, India

Predatory potential of all instar larvae and adults of Coccinella undecimpunctata (Coleoptera, Coccinellidae), using Aphis craccivora Koch (Hemiptera, Aphididae) was assessed in laboratory settings. The study, conducted with varying aphid densities in rearing jars, showed a significant increase in prey consumption as aphid density rose. Furthermore, prey consumption heightened with larval development, with 4th instars devouring more aphids compared to earlier instars. Female adults exhibited greater aphid consumption than males. Deploying both 4th instar larvae and adults could enhance pest suppression.

Resistance Realized Heritability and Fitness Cost of Cyproflanilide in Rice Stem Borer, Chilo suppressalis (Lepidoptera: Pyralidae)

The rice stem borer (RSB) Chilo suppressalis is a devastating rice pest with resistance to a number of insecticides. Recently, the new meta-diamide insecticide cyproflanilide has been considered an effective insecticide to control RSB. However, its resistance risk has not been reported. In the present study, we aimed to assess the resistance risk and evaluate the fitness cost after the RSB was exposed to cyproflanilide. After five generations of selection, the resistance level of RSB increased by 1.5-fold. When h2 was 0.125, a 10-fold resistance increase in the LD50 values was expected in fourteen and thirty-one generations at the selection intensity of 90% and 50%, respectively. The selected population (RSB-SEL) had significant differences in the developmental duration of eggs, 1st, 2nd, 3rd, and 6th instar larvae, and female pupae compared to the unselected population (RSB-UNSEL). Besides, the adult longevity was shortened, and the average pupal weight of males, the emergence rate, the sex ratio, the oviposition, the mean fecundity, and the full life cycle rate were decreased in RSB-SEL. The intrinsic rate of increase (r), the net reproductive rate (R0), and the finite rate of increase (λ) of RSB-SEL were significantly lower than those of RSB-UNSEL, while the mean generation time (T) of RSB-SEL was significantly longer than that of RSB-UNSEL. Based on the results of the prediction of the generations required for a 10-fold resistance increase in the LD50, a potential risk of resistance development exists in RSB after continuous and excessive use of cyproflanilide. These results will be useful in designing the dose of cyproflanilide to control C. suppressalis in field.

Evaluation of Larvicidal Properties of Zingiber officinale Rhizome and Allium Sativum Bulbs against Aedes aegypti

This study evaluates the larvicidal potential of methanolic extracts derived from Zingiber officinale (ginger) rhizome and Allium sativum (garlic) bulbs against the 4th instar larvae of Aedes aegypti, a key vector responsible for transmitting diseases such as dengue, yellow fever, chikungunya, and Zika. Due to the increasing resistance of mosquitoes to conventional insecticides, there is a pressing need for alternative, eco-friendly vector control methods. Botanical extracts, known for their pesticidal properties, offer a promising solution. Methanolic extracts were collected from the selected test plant parts and different test solutions were prepared to test their larvicidal efficacy against the fourth instar larvae of Ae. aegypti. The results indicated a significant dose-dependent increase in larval mortality for both extracts. The extracts of Z. officinale consistently showed better larvicidal effects than outperformed the extracts of A. sativum at all tested concentrations, with mortality rates ranging from 14.29% at 62.5 ppm to 79.22% at 500 ppm. In contrast, A. sativum exhibited mortality rates from 11.69% at 62.5 ppm to 76.62% at 500 ppm. The LC50 values further highlighted the greater efficacy of ginger extract, with an LC50 of 219.10 ppm compared to 237.39 ppm for garlic. These results suggest the usage of extracts of ginger rhizomes and garlic bulbs as eco-friendly larvicides against Ae. aegypti mosquitoes.

BmEL-2 promotes triglyceride metabolism by regulating BmAGPATγ and BmFAF2 expression in Bombyx mori.

Bombyx mori ELAV-like-1 (BmEL-1) and B. mori ELAV-like-2 (BmEL-2) are 2 members of the ELAV-like family of RNA-binding proteins. Mutations in Bmel-1 and Bmel-2 resulted in 5.8% and 28.5% decreases in larval weight on the 3rd day of the 5th instar larva (L5D3), respectively. Triglycerides (TG) are the most important energy resource and are the main component of neutral fat (NF) in animals. To investigate the role of Bmelav-like genes in the synthesis and decomposition of TG, transcriptomic, and metabolic analyses were performed on the whole bodies on the 1st day of the 2nd instar larvae (L2D1) and on fat bodies on L5D3 of Bmel-1- and Bmel-2- mutants, respectively. As compared with the control silkworm, differentially expressed genes generated in both mutants were mainly enriched in lysine degradation, fatty acid (FA) metabolism, and unsaturated FAs biosynthesis. The diglyceride and phosphatide contents were significantly lower in Bmel-1- and Bmel-2- fat bodies than those of the control group. Consistently, the NF content of both mutants' fat bodies were reduced by 50% and 60%, respectively. BmEL-2 positively regulates BmAGPATγ (B. mori 1-acyl-sn-glycerol-3-phosphate acyltransferase gamma, LOC101741736) and BmFaF2 (B. mori fatty acid synthetase-associated factor 2, LOC101739090) expression by binding to the specific regions of their 3' untranslated regions in BmN cells. This study suggests that BmEL-2 may be an important regulator of BmAGPATγ and BmFAF2 expression and thereby participates in TG metabolism in the silkworm fat body.

Knockdown of the glucosamine-6-phosphate N-acetyltransferase gene by RNA interference enhances the virulence of entomopathogenic fungi against rice leaffolder Cnaphalocrocis medinalis

Insect cuticle acts as a first line of defense and a physical protective barrier against entomopathogens. Chitin biosynthesis pathway plays a crucial role in chitin formation in the cuticle of insects. Glucosamine-6-phosphate N-acetyltransferase (GNA) is a key enzyme in insect chitin biosynthesis that regulate the chitin formation. However, how GNA-mediated cuticle metabolism influences virulence of entomopathogenic fungi is still unknown. In this study, CmGNA gene was cloned and characterized from the rice leaffolder Cnaphalocrocis medinalis. The CmGNA contains an open read frame (ORF) 600 nucleotides, encoding 199 amino acids with an isoelectric point of 8.65 and a molecular weight of 22.30 kDa. The expression profile showed that CmGNA was highly expressed in 4th instar larvae and in the cuticle. Here, we also reported the impact of CmGNA gene and entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana, on expression pattern of chitin biosynthesis genes, feeding behavior, survival rate and average body weight of infected larvae, phenotypic deformities, rate of pupation, and adult emergence. Our results showed that knockdown of CmGNA and application of M. anisopliae and B. bassiana three days after RNA interference (RNAi) significantly decreased the expression of CmGNA and other associated genes, reduced feeding efficiency and survival rate, and caused loss of average body weight, less rate of pupation and adult emergence of infected larvae. Knockdown of CmGNA gene also increased the lethality of larvae caused by M. anisopliae and B. bassiana and resulted in significantly phenotypic deformities of infected larvae. Our findings illustrated that RNAi-mediated CmGNA knockdown disturbed the chitin synthesis genes that led to enhancing the virulence of M. anisopliae and B. bassiana, which can provide us new insights to develop novel biocontrol strategies against C. medinalis.

Optimization of Rhizoclonium hieroglyphicum extract for enhanced synthesis of nickel oxide nanoparticles using response surface methodology and its potential exploration in biological application.

The study investigates the potential of Rhizoclonium hieroglyphicum as a novel source for synthesizing nickel oxide nanoparticles (RH-NiONPs) and evaluates its biological applications. Phytochemicals in the algal extract serve as capping, reducing and stabilizing agent for nickel oxide nanoparticles. The process variables were optimized using BBD based RSM to obtain maximum RH-NiONPs. Characterization of RH-NiONPs using UV-Vis and FT-IR spectroscopy reveals the plasmon resonance peak at 340 nm and the functional groups responsible for reduction and stabilization. XRD confirmed the crystalline nature while the stability and size of the RH-NiONPs were determined by DLS and zeta potential. Toxicity assessments demonstrated the effect of RH-NiONPs against Vigna radiata, Allium cepa and Artemia salina was low. RH-NiONPs revealed significant zone of inhibition against the selected bacteria and fungi. The results of larvicidal activity showed that RH-NiONPs are toxic to 4th instar larvae of Daphnis nerii. Also, RH-NiONPs efficiently decolorized Reactive Violet 13 (92%) under sunlight irradiation and the experimental data well fits to Langmuir isotherm along with pseudo second order kinetic model. The thermodynamic studies enunciate the exothermic and non-spontaneous photocatalytic decolorization of reactive violet 13. Thus, the current study assesses the eco-friendly and cost-effective nature of RH-NiONPs along with its biological applications.

The development of silk glands and transcriptome aberration induced by cyantraniliprole in Bombyx mori

Bombyx mori is an insect species of great economic importance, and its silk gland is a vital organ for the synthesis and secretion of silk protein. However, long-term artificial domestication of B. mori has resulted in high sensitivity to chemical toxins, especially insecticides. Cyantraniliprole (Cya), a second-generation ryanodine receptor modulator insecticide, is widely utilized in agriculture for pest control. In this study, the impact of Cya toxicity on the development of silk glands in the 5th instar larvae of B. mori was assessed using Cya LC5, LC10 and LC20, as well as a starvation treatment group for comparison. Short-term exposure (24 h) to different concentrations of Cya resulted in delayed development of silk glands in B. mori. Meanwhile, the body weight, silk gland weight, silk gland index and cocoon quality were significantly reduced in a concentration-dependent manner, except for the Cya LC5 treatment. Histopathological and ultrastructural analysis revealed that Cya LC10 induced disruption of the nuclear membrane and endoplasmic reticulum in the posterior silk gland (PSG) cells, leading to the formation of intracellular vacuoles. Transcriptome sequencing of PSGs identified 2152 genes that were differentially expressed after exposure to Cya LC10, with 1153 down-regulated genes and 999 up-regulated genes. All differentially expressed genes were subjected to functional annotation using gene ontology and Kyoto encyclopedia of genes and genomes database, and it was found that protein synthesis-related pathways were significantly enriched, with the majority of genes being down-regulated. Furthermore, the transcription levels of genes involved in “protein processing in endoplasmic reticulum”, “protein export”, “proteasome” and “DNA replication” were quantified using qRT-PCR. Our findings suggested that short-term exposure to Cya LC10 resulted in disruption of DNA replication, as well as protein transport, processing and hydrolysis in the PSG cells of B. mori. The results of this study provide a theoretical foundation for the safe utilization of Cya in sericulture production.

A short-term impact of enriched CO2 [eCO2] on select growth performance of Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) and its host plant Gossypium barbadense L. (Malvaceae)

Natural interactions between herbivorous insect pests and their host plants are expected to be altered significantly as atmospheric CO2 concentrations (aCO2) continue to rise according to climate change scenario. The possible effect of enriched CO2 (eCO2) environments on these interactions is under attention. To better understand such effects on select insect growth parameters; early (3rd) and penultimate (6th) instar larvae of the Cotton Leaf Worm Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae), reared on the cotton plant leaves Gossypium barbadense L. (Malvacae) grown under either ambient (aCO2 = 350 ppm) or enriched (eCO2 = 700 ppm) atmospheres were investigated.

Purification and characterization of α-amylase from Acanthoscelides obtectus (Say) (Coleoptera: Chrysomelidae)

Acanthoscelides obtectus is one of the most notorious pests of stored kidney beans (Phaseolus vulgaris) worldwide. Kidney beans are an important source of food for these insects. α-Amylase is the main carbohydrate-digesting enzyme in animals including insects. In the current study, the biochemical analysis revealed higher α-amylase activity (U/ml) in 3rd and 4th larval instars but decreased gradually in subsequent developmental stages. However, the specific activity (U/mg) interestingly was highest in 1st instar and decreased in further developmental stages. During qualitative analysis of α-amylase using starch-agar and native PAGE, the maximum zone of starch lysis and a prominent band on the gel was observed in 3rd and 4th larval stages. The molecular mass of the native enzyme was also estimated and found to be 30.34 kDa. The crude α-amylase was further purified by ammonium sulfate precipitation, gel filtration on a Sephadex G-75, and ion exchange chromatography on the DEAE cellulose column. The purified amylase was found to be a monomer with a molecular mass of 15 kDa. The specific activity of the purified enzyme increased from 1.74 U/mg in the crude sample to 166.35 U/mg in the final purification step resulting in 95-fold purification with a yield of 11.14%. Further characterization of purified α-amylase revealed a pH optimum of 7.0 and a temperature optimum of 35 °C. Lineweaver-Burk plot analysis revealed Km and Vmax to be 0.09% and 3.3 U/mL, respectively. Oxalic acid, tannic acid, and HgCl2 significantly inhibited the enzyme, while the Na+, Ca++, and Mg++ ions acted as activators. In conclusion, the study revealed, the highest α-amylase activity in 3rd and 4th larval stages of Acanthoscelides obtectus followed by native and SDS PAGE resulting in molecular mass of 30.34 and 15 kDa respectively.

Efficient CRISPR/Cas9-mediated ebony gene editing in the greater wax moth Galleria mellonella.

The greater wax moth, Galleria mellonella (Lepidoptera, Pyralidae), is a major bee pest that inflicts considerable harm on beehives, leading to economic losses. It also serves as a valuable resource insect and a model organism. The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system plays a crucial role in improving economic insect breeding and developing efficient agricultural pest management systems in Lepidoptera. However, the CRISPR/Cas9 protocols have not been developed for G. mellonella. Here, the Gmebony knockout (KO) strain was established using the CRISPR/Cas9 genome editing system. We obtained Gmebony KO strain in the G4 generation, which took approximately 10 months. When compared with wild-type, the head, notum, and the terminal abdominal surface of 1st to 4th instar larvae in the KO strain changed from yellow to brown, and these regions of the KO strain gradually transformed into a black color from the 5th instar larvae, and the body color of the adult moth in the KO strain changed to black. The developmental period of the early larval and the following larval instars extended. The embryonic hatchability of the Gmebony KO strain was significantly decreased. The pupal body weight of the Gmebony KO strain was not affected. The feasibility of the CRISPR/Cas9 methodology was validated by single-target editing of Gmebony. Our findings provide the first evidence that the ebony gene can serve as a pigmentation reference gene for genetic modifications of G. mellonella. Meanwhile, it can be utilized in the development of genome editing control strategies and for gene function analyses in G. mellonella.

Biopesticidal Potential of Lippia javanica (Burm. F) Spreng. Leaf Extracts and their Fractions against Spodoptera litura (Fab.)

Three organic solvent extracts of Lippia javanica leaves were screened for their antifeedant and larvicidal activities against the 4th instar larvae of Spodoptera litura at 5% concentration. The maximum antifeedant and larvicidal activities were recorded in ethyl acetate extract (76.57%) for antifeedant and (90.40%) for larvicidal activity, followed by chloroform and hexane extracts. Ten fractions were obtained from the ethyl acetate extract of L. javanica by using different combinations of hexane and ethyl acetate as the mobile phase through column chromatography. The fractions were screened at 1000 ppm concentrations for antifeedant and larvicidal activities. Fraction 10 (71.75%) was found to be the most effective one, followed by fraction 4 (61.32%) and fraction 7 (60.58%) for antifeedant acitivity. At a 1000 ppm concentration, fraction 3 exhibited the highest larvicidal activity (79.20%) against S. litura, followed by fraction 1 (76.0%), while fractions 5 and 6 have shown equal activity. Quantitative protein analysis revealed that treatment with the eighth fraction reduced the haemolymph protein drastically (1.52 mg/mL) compared to control (2.84 mg/mL) and other fractions. In the reference control azadirachtin treatment, the haemolymph protein quantity was found to be nearly the same (1.4 mg/mL) as that of the eighth fraction. Treatment with the first and second fractions resulted in increased haemolymph protein (8 and 7.6 mg/mL, respectively). The bio-efficacy of L. javanica in pest management is discussed.

Effects of modified atmospheres, temperature and humidity on the growth and development of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) in feihe infant milk powder

Tribolium castaneum (Herbst) is a common stored product pest that damages various stored goods across the global. To identify the effects of modified atmospheres (MA), humidity and temperature on the growth and development of T. castaneum in Feihe infant milk powder, the modified atmospheres were set at 75% nitrogen (N2) and 25% carbon dioxide (CO2), with air as the control. Two different temperatures and humidities were set at 30 °C, RH 80% and 25 °C, RH 40%. The results revealed that T. castaneum larvae exposed to the warm and moist southern conditions (30 °C, RH 80%) feeding on flour and yeast diet had a significantly shorter developmental duration. The larval weights were significantly increased in T. castaneum feeding flour and yeast diet compared with those of T. castaneum feeding milk powder under high temperature. The elevated temperature significantly increased the mortality of larvae. However, 4.4% of the survival larvae successfully grow into adults at the cool and dry northern conditions (25 °C, RH 40%). The mortality rate of eggs was 100% when eggs were sealed and treated by MA under warm and moist temperature and humidity for 96 h, and the mortality rate of 5th instar larvae increased to 100% on 7th day. Moreover, the activities of CAT and GST were decreased in all stages of T. castaneum feeding on infant milk under temperature and humidity stress. Additionally, 5th instar larvae fed with infant milk powder showed significantly fluctuated activity of POD, SOD and P450 in all stages of T. castaneum. However, T. castaneum is more susceptible to milk powder sealing with air under warm and moist temperature and humidity. The present investigation demonstrated that temperature treatment and modified atmospheres effectively prevented growth and development of T. castaneum in milk powder. These results also contribute to suitable strategies for storage of milk power.

Efficacy of Aegle marmelos (L.) Corrêa leaf extracts against 4th instar larvae of the mosquito Culex quinquefasciatus Say (Diptera: Culicidae)

Efficacy of Aegle marmelos (L.) Corrêa leaf extracts against 4th instar larvae of the mosquito Culex quinquefasciatus Say (Diptera: Culicidae)

Humidity modifies species-specific and age-dependent heat stress effects in an insect host-parasitoid interaction.

Climate change is projected to increase the frequency and intensity of extreme heat events, and may increase humidity levels, leading to coupled thermal and hydric stress. However, how humidity modulates the impacts of heat stress on species and their interactions is currently unknown. Using an insect host-parasitoid interaction: the Indian meal moth, Plodia interpunctella, and its endoparasitoid wasp, Venturia canescens, we investigated how humidity interacted with heat stress duration, applied at different host developmental stages, to affect life history traits. Hosts parasitized as 4th instar larvae and unparasitized hosts were maintained in high- (60.8% RH) or low-humidity (32.5% RH) at constant 28°C. They were then exposed to a 38°C thermal stress with a duration of 0 (no heat stress), 6 or 72 h in either the 4th or 5th host instar. Neither humidity nor heat stress duration affected emergence of unparasitized hosts, but increasing heat stress duration during the 4th instar decreased parasitoid emergence irrespective of humidity. When applied during the 5th instar, increasing heat duration decreased parasitoid emergence under low humidity, but no effect of heat stress was found under high humidity. Moreover, experiencing longer heat stress in the 4th instar increased host larval development time and decreased body size under high humidity, but this effect differed under low humidity; increasing heat duration in the 5th instar decreased parasitoid body sizes only under low humidity. Larval stage and heat stress duration directly affected parasitized host survival time, with a concomitant indirect reduction of parasitoid sizes. We show that humidity modifies key life history responses of hosts and parasitoids to heat stress in species-specific ways, highlighting the potential importance of humidity in regulating host-parasitoid interactions and their population dynamics. Finally, we emphasize that interactions between environmental stressors need to be considered in climate change research.

Climate change and its impact on sericulture

Climate change refers to the global phenomenon of rapid transformation in natural climate patterns like rain, wind, heat and more. Climate change poses a significant challenge to the existence of species and the stability of ecosystems on a global scale. The escalation in the Earth's atmospheric temperature is predominantly influenced by the heightened levels of greenhouse gases (GHG), including carbon dioxide (72%), methane (18%) and nitrous oxide (9%). (Bora et al., 2022). Agriculture is directly dependent on climate change and weather in India. The climate change viz., temperature, rainfall and carbon dioxide showed impact on crop growth and production in the country (Ram et al., 2016). Temperature fluctuations impact silkworm behavior, development, survival, growth and reproduction as highlighted by Neelaboina et al. in 2018. Silkworms are ectothermic organisms meaning that, their body temperature closely aligns with their surrounding environment. Consequently, alterations in temperature can significantly impact insect behavior, distribution, development, survival, growth and reproduction. Elevated air temperatures particularly during the 4th and 5th larval instars pose a significant climatic challenge that can adversely affect both silkworms and cocoon crops. The issues arising from these unfavorable conditions can be effectively mitigated by adhering to the recommended silkworm rearing technologies as outlined by Tripath et al. (2017).

Isolation and Identification of Entomopathogenic Fungi from the Soils of Northwest Iran and their Biological Control Efficacy on the Flour Moth (Ephestia kuehniella)

Entomopathogenic fungi have the potential to serve as alternatives to or supplements for chemical pesticides in insect biocontrol, with many of these fungi being utilized in commercial and integrated pest control practices globally. This study aimed to isolate and evaluate the efficacy of various entomopathogenic fungi for the biocontrol of the flour moth, Ephestia kuehniella (Lep: Pyralidae). Multiple isolates of entomopathogenic fungi were acquired from soils across different districts of Azerbaijan province in northwest Iran, and their virulence against E. kuehniella larvae was assessed. Seventeen isolates representing diverse entomopathogenic fungi were isolated and purified using the soil trap method from 20 distinct soil samples. Their pathogenicity against E. kuehniella was evaluated in three replicates through the immersion technique at concentrations of 104, 105, 106, 107, and 108 conidia/mL. Identification of selected fungal isolates was based on morphological features, mycological parameters, and sequencing of the internal transcribed spacer (ITS) region. The study identified seven fungal species, namely Lecanicillium lecanii, Beauveria bassiana, Metarhizium anisopliae, Purpureocillium lilacinum, Aspergillus oryzae, Penicillium citrinum, and Aspergillus lavus, among the 17 isolates collected. Bioassay assessments revealed the susceptibility of 4th-instar larvae of E. kuehniella to the selected isolates, with the larval mortality rate increasing with higher conidial concentrations. A. lavus, A. oryzae, P. citrinum, and P. lilacinum exhibited maximum virulence, causing nearly 90% lethality, while Metarhizium anisopliae demonstrated the lowest level of virulence, resulting in approximately 30% lethality in E. kuehniella. The virulence pattern of isolates across different concentrations was notably distinct. The findings of this research demonstrate that entomopathogenic fungi isolated in this investigation could be effectively incorporated into future pest management programs.

Age-Stage, Two-Sex Life Table of an Alarming Quarantine Pest Trogoderma granarium on Stored Products

Trogoderma granarium (Coleoptera: Dermestidae) is a polyphagous pest of stored products and an alarming threat to food security around the globe. The current study is designed to construct the life table of T. granarium on four stored products, i.e., wheat, barley, rice, and maize at controlled conditions (33±1°C, 65% RH, and a photoperiod of 14 : 10 (L:D) h). The incubation period of T. granarium was longer (5.13 d) on maize and shorter (4.30 d) on wheat. The developmental period of 1st, 2nd, 3rd, and 4th larval instars of T. granarium was longer on maize than the other three hosts were significant. Statistical difference between the longevity of females and males was recorded, while no statistically significant difference was found in the preoviposition period. The mean fecundity values observed on wheat, barley, rice, and maize were 31.33±1.62, 26.21±1.49, 28.00±1.35, and 25.58±1.13, respectively. The highest fertility was observed in wheat and the lowest in maize. The net reproductive rate (R0) of T. granarium ranged from 8.66±2.86, 13.16±2.65, 12.53±2.27, and 10.23±2.32 offsprings on wheat, barley, rice, and maize, respectively. The highest gross reproductive value (GRR) was for T. granarium reared on barley (18.31±4.10/d), and the lowest was for maize (15.35±2.95/d). To complete the development, T. granarium took 48.97±0.68 d on maize, significantly higher than on other treatments (p<0.05). The mean generation time (T) of T. granarium was considerably affected by tested products. Based on the results of the present study, maize is a less favorable diet for the development and reproduction of T. granarium and may be considered for the management of this detrimental pest.

Molecular Cloning and Expression Profiling of Minus-C Odorant Binding Proteins from Apocheima cinerarius (Lepidoptera: Geometridae)1

Abstract Based on transcriptome data of adults and pupae, 3 Minus-C OBPs (odorant binding proteins) genes were cloned and analyzed in various tissues (including head, thorax, abdomen, legs of female and male adults, and wings of males) of Apocheima cinerarius Erschoff (Lepidoptera: Geometridae). Expression patterns were examined across the developmental stages of egg, larva (1st–5th instars), pupa (non-diapause and diapause), and adults. The qRT-PCR results revealed a significant up-regulation of OBP8 in 3rd and 4th larval instars, with the highest expression level observed in 4th-instar larvae. OBP14 exhibited higher expression levels in diapausing pupal and adult stages, with highest levels in the female adult. Conversely, OBP18 displayed highest expression in the non-diapausing pupae, while exhibiting extremely low expression levels among other stages. The tissue expression profile revealed a gradual increase in the expression of OBP14, with highest levels in the male legs, whereas the expression pattern of OBP18 exhibited an inverse trend with maximum expression observed in the male head (including antennae). OBP8 exhibited high expression levels in the abdomen of the female adult, while OBP14 showed high expression in the legs of the male adult. Additionally, OBP18 displayed high expression in the female head. These findings suggest the crucial role played by OBP genes in both olfactory and non-olfactory tissues of A. cinerarius. The results provide a fundamental basis for further investigation into the recognition of odorant binding in A. cinerarius.