Larval Weight Research Articles

Economical factitious diet for mass rearing of greater wax moth, Galleria mellonella (Lepidoptera: pyralidae), a promising host for entomopathogenic nematodes

BackgroundGreater wax moth (Galleria mellonella L.) (Lepidoptera: Pyralidae) is most commonly used for mass multiplication of entomopathogenic nematodes. An investigation on economical modification and comparative analysis of factitious diets of G. mellonella was carried out under laboratory conditions. Different diets were assessed in comparison with standard diet.ResultsModifications based on quantity change of dietary components (wheat flour, maize flour, dry milk, dry yeast, honey and glycerin), addition of vitamin E and vitamin-B complexes, elimination of dry milk and replacement of glycerin with sorbitol showed reduction in the cost of production and increase in food conversion efficiency in G. mellonella. The weight of larva in diet III (303.40 mg) was highest as compared to the larval weight in control diet (280.00mg). The conversion of ingested and digested food into biomass of G. mellonella was the highest for factitious diet III. Also, the highest number of Steinernema abbasi was produced from G. mellonella larvae reared on diet III (25418.43IJs) followed by diet I (21805.31IJs). The economics of the diets also showed that the percent cost reduction in factitious diet III and diet I was 48.86 and 28.85%, respectively. Overall, the results suggested that factitious diet III was superior to diet I followed by diet II.ConclusionAddition of supplements of vitamin E and B-complexes enhances the biological activity of the insect, thereby increasing its food conversion efficiencies. Factitious diet III can be successfully used for mass multiplication of the G. mellonella.

Effects of penthiopyrad on the hypothalamic-pituitary-thyroid (HPT) axis in zebrafish

Exposure to specific pesticides has been demonstrated to alter normal thyroid function of aquatic vertebrates. This study aimed to investigate the impact of penthiopyrad (PO) on the thyroid function of zebrafish, further elucidating its toxic mechanisms on the early developmental stages of zebrafish. Exposure to sublethal doses of PO (0.3–1.2 mg/L) for 8 days from 2 h after fertilization resulted in a significant reduction in larval swim bladder size and body weight, accompanied by developmental abnormalities such as pigment deposition and abnormal abdominal development. Perturbations in the hypothalamic-pituitary-thyroid (HPT) axis in larvae manifested as a marked upregulation of crh, tg, ttr, and ugt1ab expression, alongside downregulation of trβ expression, culminating in elevated thyroxine (T4) and triiodothyronine (T3) levels. Additionally, molecular docking results suggest that PO and its metabolites may disrupt the binding of thyroid hormones to thyroid hormone receptor beta (TRβ), compromising the normal physiological function of TRβ. These findings highlight the PO-induced adverse effects on the HPT axis of larvae under sublethal doses, eventually leading to abnormal development and growth inhibition.

Improvement of Silkworm (Bombyx mori L.) Growth and Cocoon Quality Using Nickel Sulfate Supplementation

The silkworm belongs to the order Lepidoptera and the family Bombycidae (Bombyx mori L.). The silkworm industry plays a crucial role in providing employment opportunities in India. This study investigated the effects of nickel sulfate supplementation on the growth and cocoon quality of silkworm (Bombyx mori L.). The experiment was conducted at a silkworm-rearing center in Palayamkottai, India, from December 2022 to January 2023. Silkworms were fed Victory-1 (V1) mulberry leaves soaked in different nickel sulfate solutions (100 ppm, 300 ppm, and 500 ppm). Larval weight, duration, cocoon weight, shell weight, shell ratio, and pupal weight were measured for 10 healthy silkworms with good quality cocoons selected from each treatment group. Compared to the control group, supplementation with 500-ppm nickel sulfate solution significantly improved silkworm growth performance (weight) and economic traits (cocoon weight and quality). GRAPHICAL ABSTRACT

Evaluation of Reproductive and Growth Performance in New Breeds and Hybrids of Bivoltine Silkworm (Bombyx mori L.)

This study aimed to evaluate the reproductive and growth performance of recently developed bivoltine silkworm parental breeds and their hybrids to improve silk production and ensure the long-term sustainability of sericulture. Utilizing five thermotolerant pure breeds (B1, B2, B4, B6 and B8) and four popular CSR breeds (CSR2, CSR27, CSR6 and CSR26), six foundation crosses and eight double hybrids were developed and evaluated for ten traits. Results showed that B1 exhibited superior performance in fecundity (524.00), hatching percentage (98.67%), dead eggs (1.33%), pupal weight (1.31 g), pupation rate (96.84%) and cumulative survival index (CSI) (93.84%). The foundation cross B1 × B2 excelled in fecundity (553.67), larval mortality (2.67%), pupal weight (1.53 g), ERR (97.33%) and CSI (93.27%) while FC2 performed better in hatching percentage (97.60%), dead eggs percentage (2.40%), fifth instar larval duration (157.21 h), fifth instar larval weight (35.64 g/10 larvae) and pupation rate (96.33%). Among the double hybrids, (B1 × B2) × (FC1) demonstrated superior performance in fecundity (614.33), larval mortality (1.41%), pupal weight (2.06 g), ERR (98.59%) and CSI (97.24%). FC2 × FC1 excelled in larval duration (141.11 h), fifth instar larval weight (51.96 g/10 larvae) and pupation rate (98.94%). Double hybrids showed significant improvements compared to parental breeds and foundation crosses, indicating potential for field testing and further development. These results indicate the potential of using the newly identified breeds and foundation crosses in silkworm breeding, particularly in developing new double hybrids as an alternative to established CSR breeds and hybrids.

Sublethal effects of a commercial Bt product and Bt cotton flowers on the bollworm (Helicoverpa zea) with impacts to predation from a lady beetle (Hippodamia convergens).

Insecticidal Bacillus thuringiensis Berliner (Bt) toxins produced by transgenic cotton (Gossypium hirsutum L.) plants have become an essential component of cotton pest management. Bt toxins are the primary management tool in transgenic cotton for lepidopteran pests, the most important of which is the bollworm (Helicoverpa zea Boddie) (Lepidoptera: Noctuidae) in the United States (U.S.). However, bollworm larvae that survive after consuming Bt toxins may experience sublethal effects, which could alter interactions with other organisms, such as natural enemies. Experiments were conducted to evaluate how sublethal effects of a commercial Bt product (Dipel) incorporated into artificial diet and from Bt cotton flowers impact predation from the convergent lady beetle (Hippodamia convergens Guérin-Méneville) (Coleoptera: Coccinellidae), common in cotton fields of the mid-southern U.S. Sublethal effects were detected through reduced weight and slower development in bollworm larvae which fed on Dipel incorporated into artificial diet, Bollgard II, and Bollgard 3 cotton flowers. Sublethal effects from proteins incorporated into artificial diet were found to significantly alter predation from third instar lady beetle larvae. Predation of bollworm larvae also increased significantly after feeding for three days on a diet incorporated with Bt proteins. These results suggest that the changes in larval weight and development induced by Bt can be used to help predict consumption of bollworm larvae by the convergent lady beetle. These findings are essential to understanding the potential level of biological control in Bt cotton where lepidopteran larvae experience sublethal effects.

Artificial plant-based diet for mass-rearing larvae of fall armyworm, Spodoptera frugiperda

Efforts to overcome the problems of a new pest, Spodoptera frugiperda or fall armyworm, need basic and applied research. In order to carry out the research efficiently, it is necessary to rear large numbers of test insects on an artificial diet. The present study aimed to determine the effect of an artificial diet on larval weight, adult longevity, and number of eggs laid by S. frugiperda. Artificial diets were prepared from leaf-based ingredients of land spinach (Ipomoea reptans), pigweed (Amaranthus hybridus), red mulberry (Morus rubra), and maize (Zea mays) (control). The present study indicated that the highest weight of 6th instars was found on treatment of pigweed leaves (135.79 mg), which was significantly different from others. The longest longevity of S. frugiperda adults was found on pigweed (9.06 days), but it was not significantly different from that on red mulberry (8.03 days). The highest number of eggs laid was on pigweed (94.63 eggs per female), but this was not significantly different from maize (91.30 eggs per female) and red mulberry (84.86 eggs per female). Finally, the most appropriate artificial diet for mass-rearing larvae of S. frugiperda is an artificial diet based on pigweed leaves.

Waste Reduction and Bioconversion of Quail, Chicken, and Pig Manure by Black Soldier Fly (Hermetia illucens L.)

The increasing poultry and livestock farm operations have led to a great deal of manure generation. If inappropriately managed, it may cause adverse impacts on the environment, health, and economy. Black soldier fly (Hermetia illucens L.) larvae (BSFL) can potentially convert manure into protein-rich biomass and nutrient-rich frass effectively. In this study, BSFL were reared on three different waste streams – quail manure (QM), chicken manure (CM), and pig manure (PM). Manure mass was significantly reduced by larvae, of which QM had the highest overall degradation of 62.49% and waste reduction index of 10.42% (p-value < 0.05) of dry matter (DM). The larvae reared in QM also had the highest bioconversion rate (26.41%) and individual larval weight (~ 0.22 g/larva) (p < 0.05) with DM protein and fat contents of 54.77 and 13.79%, respectively, being a potentially high protein and high energy animal feed. Meanwhile, larvae reared in CM produced the lowest larval biomass (~ 0.07 g/larva) but had the most frass (252.10 g) (p < 0.05). However, there were no significant differences in the frass composition (organic matter, nitrogen-phosphorus-potassium, and carbon-to-nitrogen ratio) from the three substrates (p > 0.05). Therefore, BSFL presents a promising solution for efficient manure management by converting it into valuable frass and larval biomass with potential applications as plant fertilizer and animal feed ingredient, respectively.

Drosophila melanogaster as a model organism for diabetes II treatment by the ethyl acetate fraction of Atriplex halimus L.

Type 2 diabetes (T2D) is the most common metabolic disorder. The undesirable effects of synthetic drugs demand a search for safe antidiabetic agents. This study aimed to assess the antidiabetic activity of different fractions of Atriplex halimus (petroleum ether 60-80, methylene chloride, ethyl acetate, and n-butanol) using Drosophila melanogaster larvae. Titers of total glucose and trehalose, as well as larval weight, were measured and compared with those of control and diabetic larvae. The expression of Drosophila insulin-like peptides (DILP2 and DILP3) and adipokinetic hormone (AKH) was evaluated. The results revealed a significant increase in total glucose, trehalose, and a decrease in body weight in the larvae fed a high-sugar diet compared with those in the control. When larvae fed diets containing the tested fractions, the total glucose and trehalose decreased to the control level, and the body weight increased. DILP2, DILP3, and AKH exhibited significant decreases upon treatment with A. halimus ethyl acetate. Metabolomic profiling of the ethyl acetate fraction of A. halimus revealed the presence of flavonoids and flavonoid glycosides. After docking screening to predict the most powerful moiety, we discovered that flavonoid glycosides (especially eriodictyol-7-O-neohesperidoside) have a greater affinity for the pocket than the other moieties. The results indicated the therapeutic activity of the A. halimus ethyl acetate fraction against induced T2D in Drosophila larvae. The antidiabetic activity may be attributed to flavonoids, which are the main components of the A. halimus ethyl acetate fraction.

How to reduce waste using black soldier fly larvae and produce a high-quality product

Abstract With the growing human population the demand for protein is rising and waste production is increasing. Insects can provide a sustainable solution for both problems and produce food (protein and fat) from waste. Our study tested the ability of the black soldier fly (BSF) to reduce agricultural waste and produce a high-value product rich in unsaturated fatty acids. Initially, we tested the diet limitations of the larvae. We tested the composition of the agricultural wastes (brewery and avocado wastes) and the ability of the larvae to grow on them. A mixed diet based on brewery and avocado wastes was composed to increase larval weight and improve their fatty acid composition. The larvae were limited by the protein and water content of the diet (7% and 70%, respectively). The mixed diet that met the requirements of a minimal ratio of protein (7%) and optimal water content (70%), did not improve larval weight but increased the unsaturated fatty acid content. Therefore, using BSF larvae to reduce waste and produce protein is feasible; however, the end product should be considered when composing their diet from a waste mixture.

Larval biomass production from the co-digestion of mushroom root waste and soybean curd residues by black soldier fly larvae (Hermetia illucens L.).

People are increasingly using black soldier fly larvae (BSFL) as a sustainable waste management solution. They are high in protein and other essential nutrients, making them an ideal food source for livestock, poultry, and fish. Prior laboratory studies with BSFL developed on pure mushroom root waste (MRW) showed poor conversion efficiency compared to a regular artificial diet. Therefore, we mixed the nutrient-rich soybean curd residues (SCR) with MRW in different ratios (M2-M5). Pure mushroom root waste (M1, MRW 100%) had the lowest survival rate (86.2%), but it increased up to 96.9% with the SCR percentage increasing. M1 had the longest developmental period (31.1days) and the lowest BSFL weight (7.4g). However, the addition of SCR reduced the development time to 22.0 and 21.5days in M4 (MRW 40%, SCR 60%) and M5 (MRW 20%, SCR 80%), respectively, and improved the larval weight to 10.9g in M4 and 11.8g in M5. Other groups did not have as much feed conversion ratio (FCR) (8.4 for M4 and M5), bioconversion (M4 5.4%; M5 5.9%), or lipid content (M4 25.2%; M5 24.3%). These mixtures did.Compare this to M1. We observed better results, with no significant differences between the M4 and M5 groups and their parameters. In the present study, our main target was to utilize more MRW. Therefore, we preferred the M4 group in our nutritional and safety investigation and further compared it with the artificial diet (M7). The heavy metals and essential amino acids (histidine 3.6%, methionine 2.7%, and threonine 3.8%) required for human consumption compared to WHO/FAO levels showed satisfactory levels. Furthermore, fatty acids (capric acid 1.9%, palmitic acid 15.3%, oleic acid 17.3%, and arachidonic acid 0.3%) also showed higher levels in M4 than M7. The SEM images and FT-IR spectra from the residues showed that the BSFL in group M4 changed the structure of the compact fiber to crack and remove fibers, which made the co-conversion mixture better.

Selected Thermotolerant Bivoltine Hybrids of Bombyx mori L. Exhibit Desirable Heterosis for Quantitative Traits under Beauveria bassiana Infection

Four thermotolerant bivoltine silkworm parents viz., B1, B4, B6 and B8 and their 12 hybrids viz., B1×B4, B1×B6, B1×B8, B4×B1, B4×B6, B4×B8, B6×B1, B6×B4, B6×B8, B8×B1, B8×B4 and B8×B6 were used in the experiments. One set of the parents and their hybrids were inoculated with Beauveria bassiana spore suspension (9.04 × 104 spores / ml), on the first day of the fifth instar before first feed and another set were exposed to high temperature (36 ± 1o C temp. & 85 ± 5 % RH) and their responses were studied in terms of heterotic expression of quantitative traits. Significantly highest positive relative heterosis under normal condition was recorded in B1×B4 hybrid for five characters (fifth instar larval weight, cocoon yield by weight, single cocoon weight, shell weight and filament length) and under muscardine inoculation significantly highest positive relative heterosis was recorded in the hybrid B4×B6 for ten characters (ERR, cocoon yield by number, fifth instar larval weight, cocoon yield by weight, single cocoon weight, shell weight, shell ratio, pupal weight, filament length and filament weight). Heterosis scoring over all the traits under muscardine inoculation revealed that the hybrid B4 × B6 scored high overall status of heterotic effects across the characters. Thus, B1 and B8 among parents and B1 × B8 and B4 × B6 among hybrids could be selected for dual stress tolerance against high temperature and muscardine disease.

Investigation of Genotoxic and Development Effects of Tetramethrin on Drosophila melanogaster

The adverse effects of tetramethrin residues, a synthetic pyrethroid used in many insecticide formulations, on environmental health and living organisms are a matter of concern. The aim of this study was to evaluate the genotoxic and developmental effects of tetramethrin in a non-target organism, Drosophila melanogaster. Thus, its effect on DNA damage was evaluated using the Comet assay in hemocytes, and its mutagenic and recombinogenic effects were evaluated using Drosophila wing SMART. Also, the effects of tetramethrin on Drosophila development were evaluated by measuring larval weight, larval length, and fecundity. Results showed that tetramethrin induced a decrease in the larval weight and length only at a high concentration. Moreover, a decrease in fecundity in a dose-dependent manner was observed. According to the Comet assay results, DNA damage was not induced because there was no significant increase in % DNA. However, tetramethrin caused genotoxicity by inducing mitotic recombination in the SMART assay.

The Essential Oils Compounds of Lippia multiflora Moldenke and Cymbopogon schoenanthus (L.) Spreng Repel and Affect the Survival of the Maize Pest Spodoptera frugiperda (Lepidoptera: Noctuidae) Larvae

Plant-derived insecticides, such as essential oils, can be an effective alternative to replace synthetic chemical insecticides against Spodoptera frugiperda, which becomes increasingly resistant to synthetic products. This study aims to evaluate essential oils (EOs) effects on larval growth and development following feeding inhibition, growth regulation, and repellency of EOs of Lippia multiflora (Verbenaceae), Cymbopogon schoenanthus (Poaceae), and their combination. Topical application of EOs was used on S. frugiperda larvae for larvicidal effect or treating filter paper with the EOs to find repellency. The effect of EOs on food intake and larval growth was also evaluated. Several types of compounds have been identified in the EOs, mainly monoterpenes with the appearance of new compounds in the 1 : 1 combination. Bioassay results show that individuals and combinations of EOs significantly influenced S. frugiperda larval development. L. multiflora caused 100% mortality of L2 larvae within 24 hours at 3%. The Lm + Cs (1 : 1) EOs combination was the most effective with LC50 and LC90 of 1.02% and 1.92%, respectively. Lm + Cs (1/4 : 3/4) EOs caused the highest inhibition of food consumption, 0.0160 g consumed after food was treated with 2.2% concentration compared to food consumption of 0.0602 g for the control group at 24 hours. Lower food consumption caused the inhibition of larval growth and weight loss of 0.0005 g/day at the 2.2% EOs concentration. The highest repellency effect of the EOs was found in EOs of L. multiflora, exhibiting a repulsion of 83.33% of the larvae after 3 hours of exposure. This diversity in the biological actions of the EOs tested on S. frugiperda represents valuable options for contributing to integrated pest management and an alternative to synthetic chemical insecticides.

Larval performance of Zophobas morio (F.) (Coleoptera: Tenebrionidae) on various diets enriched with post-distillation residues and essential oils of aromatic and medicinal plants

The increasing demands for resources driven by the global population necessitate exploring sustainable alternatives for affordable animal protein over the use of traditional protein sources. Insects, with their high protein content, offer a promising solution, especially when reared on agricultural post-distillation residues for enhanced sustainability and cost-effectiveness. We assessed the development of Zophobas morio (F.) (Coleoptera: Tenebrionidae) larvae on diets enriched with essential oils and post-distillation residues from Greek aromatic and medicinal plants. Two aromatic plant mixtures (A and B) were examined. Mixture A consisted of post-distillation residues, while Mixture B incorporated these residues along with essential oils. Insect rearing diets were enriched with different proportions (10, 20, and 30 %) of these mixtures, with wheat bran serving as the control. Enrichment positively influenced larval development without compromising survival. Larval weight remained unchanged with Mixture A, but improved with Mixture B. No adverse effects were detected in the case of the enriched diets, although higher concentrations of Mixture B prolonged development time.

Effect of four host plants on the life history and nutritional indices of Spodoptera Littoralis

The Egyptian cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) is a pervasive and highly polyphagous insect pest. As S. littoralis has developed resistance to major classes of conventional insecticides and the use of these insecticides has caused negative impacts on the ecosystems, it is necessary to search for eco-friendly, cost-effective, and sustainable agents to control. This can be achieved by identifying the preferred host plant. The present study aimed at evaluating the impacts of four host plants– castor bean, tomato, potato, and cucumber on the various life-history traits and nutritional indices of S. littoralis. The concentrations of nitrogen, potassium, and phosphorous in the tested host plants were quantified. Newly hatched larvae were divided into four groups. Each group was fed only on one type of the four tested host plants until pre-pupal stage. Then, the life-history traits and nutritional indices were determined. Larvae fed on castor bean showed the highest adult emergence, weight of full-grown larvae, number of eggs per female, and egg-hatch percent, food consumption, relative growth rate, and food utilization efficiencies. Whereas, larvae fed on cucumber showed the lowest egg-hatch percent, food consumption, relative growth rate, and food utilization efficiencies. There was a positive correlation between nitrogen and phosphorous concentrations in the tested host plants and larval weight, with the highest concentrations in castor bean. Castor bean was the most preferred host plant.

Using kin discrimination to construct synthetic microbial communities of Bacillus subtilis strains impacts the growth of black soldier fly larvae.

Using synthetic microbial communities to promote host growth is an effective approach. However, the construction of such communities lacks theoretical guidance. Kin discrimination is an effective means by which strains can recognize themselves from non-self, and construct competitive microbial communities to produce more secondary metabolites. However, the construction of cooperative communities benefits from the widespread use of beneficial microorganisms. We used kin discrimination to construct synthetic communities (SCs) comprising 13 Bacillus subtilis strains from the surface and gut of black soldier fly (BSF) larvae. We assessed larval growth promotion in a pigeon manure system and found that the synthetic community comprising 4 strains (SC 4) had the most profound effect. Genomic analyses of these 4 strains revealed that their complementary functional genes underpinned the robust functionality of the cooperative synthetic community, highlighting the importance of strain diversity. After analyzing the bacterial composition of BSF larvae and the pigeon manure substrate, we observed that SC 4 altered the bacterial abundance in both the larval gut and pigeon manure. This also influenced microbial metabolic functions and co-occurrence network complexity. Kin discrimination facilitates the rapid construction of synthetic communities. The positive effects of SC 4 on larval weight gain resulted from the functional redundancy and complementarity among the strains. Furthermore, SC 4 may enhance larval growth by inducing shifts in the bacterial composition of the larval gut and pigeon manure. This elucidated how the SC promoted larval growth by regulating bacterial composition and provided theoretical guidance for the construction of SCs.

Density-dependent development of the yellow mealworm Tenebrio molitor (Coleoptera: Tenebrionidae)

Abstract The increasing global population has led to high food demand and the interest for alternative resources is highly topical. The interest in utilizing insects as a source of food and feed has been rapidly increasing, as the on-growing population has made the need for protein even more demanding. Insect rearing is economically viable, since they can be fed with organic waste and agricultural by-products. The inclusion of bioactive compounds and active ingredients in insect diets has been identified as a potential key factor for enhancing their growth and performance. The aim of this study was to evaluate the effect of a diet enriched with functional ingredients of medicinal and aromatic plants and agricultural by-products of the Greek flora on the growth, survival and development of larvae of the yellow mealworm, Tenebrio molitor (Coleoptera: Tenebrionidae), in the context of larval density-induced stress. Wheat bran enriched with 5%, 10% or 20% of a prepared mixture containing post-distillation residues of medicinal and aromatic plants of the Greek flora (oregano, thyme, sage and rosemary, linseed oil, rock-samphire, industrial cannabis, and olive paste by-product) was evaluated as insect feeding substrate, whereas wheat bran alone (0% enrichment) served as control. Groups of 25, 50, 75 and 100 first instar larvae were separately collected, weighed, and put in cylindrical plastic cups to test if larval density had any effect on survival and development. According to our results, the final larval weight of T. molitor is significantly affected by the density of larvae but not by the rearing substrate. The highest individual weight among all tested substrates was achieved at the density of 25 larvae. Individual weights were highest when larvae were reared on 5% mixture. The weight of those reared on the control substrate was slightly lower, followed by the 10% and 20% mixtures. Larvae fed with 10% enriched substrate showed the highest survival rate, followed closely by those fed with the control and 5% substrates. Our results clearly demonstrate that larval survival is not density dependent, but density is important in the case of individual larval weight.

Bean Sprouts, Lettuce, and Milk as Water Sources in Tenebrio molitor Larval Growth.

The Tenebrio molitor larva (yellow mealworm) holds great potential as a sustainable ingredient in food and feed. Optimizing its growth under mass farming requires careful water management. However, the availability and cost of fresh fruit and vegetables, which are the most widely used sources of water, can vary geographically, which calls for the search for relatively affordable, effective, and readily available alternatives. We evaluated the effect of three water sources (bean sprouts, lettuce leaves, and milk) as well as their quantity on weights and nutrient profiles of reared T. molitor larvae. Newly hatched mealworm larvae were maintained in controlled conditions of 25 °C and 60% relative humidity under a 12-h light-dark cycle for 15 weeks. When provided as sole-supplements, bean sprouts induced the highest larval weight gains compared to fresh lettuce leaves, which in turn performed better than milk and water. However, the addition of milk to the vegetable supplements enhanced growth. Furthermore, doubling the level of water supply resulted in 70% higher larval weights by week 14 post hatching. Moreover, water sources did not change the nutrient content of the harvested larvae. These findings suggest that mealworm productivity can be enhanced by increasing water feed levels and that bean sprouts may be a superior alternative to lettuce.

Endophytic Fungi-Mediated Defense Signaling in Maize: Unraveling the Role of WRKY36 in Regulating Immunity against Spodoptera frugiperda.

Seed priming with beneficial endophytic fungi is an emerging sustainable strategy for enhancing plant resistance against insect pests. This study examined the effects of Beauvaria bassiana Bb20091317 and Metarhizium rileyi MrCDTLJ1 fungal colonization on maize growth, defence signalling, benzoxazinoid levels and gene expression. The colonization did not adversely affect plant growth but reduced larval weights of Spodoptera frugiperda. Maize leaves treated with M. rileyi exhibited higher levels of jasmonic acid, jasmonoyl-Isoleucine, salicylic acid, and indole acetic acid compared to control. B. bassiana and M. rileyi accelerated phytohormone increase upon S. frugiperda herbivory. Gene expression analysis revealed modulation of benzoxazinoid biosynthesis genes. We further elucidated the immune regulatory role of the transcription factor zmWRKY36 using virus-induced gene silencing (VIGS) in maize. zmWRKY36 positively regulates maize immunity against S. frugiperda, likely by interacting with defense-related proteins. Transient overexpression of zmWRKY36 in tobacco-induced cell death, while silencing in maize reduced chitin-triggered reactive oxygen species burst, confirming its immune function. Overall, B. bassiana and M. rileyi successfully colonized maize, impacting larval growth, defense signalling, and zmWRKY36-mediated resistance. This sheds light on maize-endophyte-insect interactions for sustainable plant protection.

Study on Biology of Fall Armyworm, Spodoptera frugiperda (J.E. Smith) on Maize, Zea mays L. in Manipur, India

Aim: To study the biology and morphometric parameters of different stages of fall armyworm, Spodoptera frugiperda.
 Study Design: Experimental study.
 Place and Duration of Study: PG laboratory, Department of Entomology, College of Agriculture, Iroisemba, CAU (Central Agricultural University), Imphal, June-August 2022.
 Methodology: The egg masses collected from maize fields were transferred to sterilized petri plates containing maize leaves and reared under laboratory conditions (25±2°C, 70±10% RH). Duration and morphometric parameters of different stages of fall armyworm were recorded regularly.
 Results: The mean incubation period of eggs was observed to be 1.90 days. The larval period of six instars were recorded to be 2-4, 2-5, 2-3, 2-3, 2-3, 2-3 and 3-6 days, respectively. The mean larval length of six instars were 1.91, 3.38, 6.15, 9.78, 18.60 and 32.30 mm, respectively. The mean larval width of six instars were 0.33, 0.74, 1.31, 2.26, 2.92 and 3.53 mm, respectively. The average larval weight of six instars were 0.0031, 0.0214, 0.0420, 0.0503, 0.0576 and 0.0652 gm, respectively. The total larval duration was observed to be 16.70 days. The male and female pupal period was found to be 7.60 and 7.10 days, respectively. The average male pupal length, width and weight were 14.79±0.18 mm, 4.54±0.14 mm and 0.17±0.01 gm, respectively. The average female pupal length, width and weight were 13.0-18.20 mm, 4.0-5.2 mm and 0.18±0.01 gm, respectively. The ovipositional period was found to be 1-6 days. Mean longevity of males and females were observed to be 8.70 and 9.00 days, respectively. The total life cycle of male and female lasted 34.90 and 35.60 days, respectively.
 Conclusion: This study clearly provides basic information about the biology of this recently invaded pest. To prevent the potential devastating occurrence, compatible integrated pest management strategies are needed at the early stages of FAW infestation.