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Frass, a byproduct of insect rearing, has become popular for its potential use in sustainable agriculture. The rapid growth of insect production results in an increased frass output. This study examined the effects of frass as soil amendment on plant growth and resistance to insect herbivory. In greenhouse experiments, Brassica rapa L. (Brassicaceae), was grown in unamended soil (NoFrass; control) or soil amended with frass (2 g kg−1) from larvae of black soldier fly (BSFF), Hermetia illucens L. (Diptera: Stratiomyidae), or yellow mealworm (MWF), Tenebrio molitor L. (Coleoptera: Tenebrionidae). Frass was applied as raw, incubated, or composted frass before seed germination. Plant growth and performance were measured of larvae of root‐feeding Delia radicum L. (Diptera: Anthomyiidae) and shoot‐feeding Plutella xylostella L. (Lepidoptera: Plutellidae). Initially, raw BSFF and MWF reduced the growth of B. rapa and resulted in a smaller leaf area than NoFrass. However, over time, a notable trend emerged. Whereas the difference in leaf area between MWF and NoFrass disappeared, BSFF consistently resulted in a smaller leaf area than MWF and NoFrass. Raw BSFF reduced D. radicum larval survival and pupal biomass and larval survival of P. xylostella. In contrast, raw MWF increased larval survival and biomass of D. radicum and the survival of P. xylostella larvae. Interestingly, incubation of frass in the soil for 16 days before seed germination removed plant growth inhibition and increased plant leaf area, especially for MWF compared to NoFrass. In addition, composting MWF increased leaf growth. Therefore, frass may be used as a sustainable and natural alternative to conventional organic fertilisers, promoting plant growth and enhancing resistance to herbivory. Our results indicate that soil amendment with raw BSFF may negatively impact herbivore performance, whereas raw MWF may enhance herbivore performance. [ABSTRACT FROM AUTHOR]

A monoclonal antibody (McAb), EGA-4A9, was developed to detect the semi-digested proteins of the English grain aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae), in predatory ladybird beetles (species of the genera Adonia, Coccinella, Hippodamia, and Propylea) using the gut homogenate of Adonia variegata (Goeze) (Coleoptera: Coccinellidae) adults which had fed on S. avenae as immunogen. The McAb was selected by screening hybridoma lines for antibodies that bound with the semi-digested aphid proteins in ladybirds. A double antibody sandwich enzyme-linked immuno-sorbent assay (ELISA) using ClonotypingTM System/HRP showed that it belonged to the IgG2a isotype. It did not cross-react with any of the 21 arthropod species tested besides the ladybird beetles fed on S. avenae with an indirect ELISA. It could still detect the semi-digested proteins in the gut of a ladybird adult, kept at 25 °C, that had ingested one aphid 6 days before. The extended antigen detection period and the high specificity of the antibody indicated that EGA-4A9 could be used to study interactions between English grain aphids and their ladybird predators in the field. Between 28 and 72% of coccinellids collected from the field were positive for English grain aphid protein by ELISA. The percentage of McAb-positive predatory ladybird beetles was positively correlated with the density of S. avenae in wheat fields. [ABSTRACT FROM AUTHOR]

The genetic basis of larval host-plant preference was investigated in reciprocal F1, F2, and backcrossed generations derived from hybrid crosses between the generalist species Helicoverpa armigera (Hübner) and the closely related specialist species Helicoverpa assulta (Guenée) (Lepidoptera: Noctuidae). Host-plant preference for cotton [ Gossypium arboreum L. (Malvaceae)] and pepper [ Capsicum frutescens L. (Solanaceae)] of fifth-instar caterpillars was tested by using a two-choice leaf-disk assay. Helicoverpa armigera and H. assulta were significantly different in their feeding preferences, but the difference was not significant in the reciprocal hybrids, which showed there were no maternal/cytoplasmic effects. Comparisons of feeding preference between different groups of females or males demonstrated that the trait was not controlled by sex-linked loci. The distributions of feeding preference index values for crosses that carried similar complements of autosomal genes were not significantly different, whereas crosses with different complements of autosomal genes were associated with significantly different feeding preferences, indicating that feeding preference of the two species for cotton and pepper, respectively, is controlled by autosomal genes. It was found that one major autosomal locus affected this feeding preference, with the H. armigera-derived alleles being partially dominant to those carried by H. assulta. The genetic analysis of hybrids contributes to understand the evolution of feeding preference in these closely related species. [ABSTRACT FROM AUTHOR]

Performance and body composition of insect larvae depend on quality and quantity of their diet, and on biotic factors such as larval density. We investigated the effect of dietary nutrient concentration and larval rearing density on survival, development, growth, and protein and fat contents of larvae of the black soldier fly (BSF), Hermetia illucens L. (Diptera: Stratiomyidae). Neonate larvae were fed with a low (NC1), intermediate (NC2), or high nutrient concentration (NC3), and with four rearing densities (50, 100, 200, or 400 larvae per container). Two feeding regimes (FR) were tested: in FR1, the amount of diet added during the experiment was based on the visually estimated larval mass present, whereas in FR2, a fixed feeding ration of 0.6 g of food per larva was applied at the start. FR1 resulted in food limitation, resulting in significantly lower body crude protein content on diet NC1 than on NC2 at larval densities 100 and 200. Larval crude fat content was higher on diets with higher nutrient concentration and at lower larval densities. For FR2, development time was shorter on diets with higher nutrient concentration and at lower larval densities. Individual larval weight and total larval yield increased with higher nutrient concentration at all four larval densities. At lower nutrient concentration, higher larval density resulted in higher individual larval weight and total larval yield, revealing an interaction between larval density and dietary quality. Larval crude protein content was higher at lower densities and lower nutrient concentration. Larval crude fat was higher at higher larval densities and nutrient concentrations. This study indicates that larval protein content is regulated within narrow limits, whereas larval crude fat content is strongly affected by nutrient concentration and by larval density.