Larval Diet Research Articles

Evolutionary changes in the ovipositor shape of xyelid sawflies (Hymenoptera: Xyelidae) revealed by early fossils

Abstract Considering taxonomic diversity, extant xyelid sawflies represent a very small subset of the past diversity of the group. A complementary approach to investigate evolutionary changes in this family is to consider ovipositor morphology, an ecologically important organ. New, well-preserved specimens from the Upper Triassic Ominé locality (Momonoki Formation, Mine Group; Carnian; Japan) and belonging to the †Madygellinae, one of the earliest Xyelidae subfamilies, are newly described and assigned to four new species, belonging to three genera (one being new). Two of the specimens expose body parts and wings, providing important information regarding ovipositor morphology. To further appreciate the evolution of this organ, we surveyed both fossil and extant Xyelidae. Extant forms display both extremes of the range of ovipositor types, namely the high aspect ratio “dagger-like” and “needle-like” types (in Xyelinae) and the low aspect ratio “short and wide” type (in Macroxyelinae). All known Triassic representatives display high aspect ratio ovipositor types. In contrast, Middle Jurassic to Lower Cretaceous sawflies show the highest diversity of ovipositor types for the family. Afterwards, the observed range declined and concentrated on the two, very distinct types known nowadays. Decline in ovipositor disparity was not contemporaneous in Xyelinae and Macroxyelinae: specialization occurred during the Jurassic-Cretaceous transition for the Xyelinae, while Macroxyelinae displayed their peak of diversity during the Lower Cretaceous, with a postponed decline. Ovipositor shape transition was probably accompanied with a larval diet change in Macroxyelinae. Ovipositor disparity therefore further contributes depicting extant Xyelidae as a subset on a once more diverse group.

Environmental stress differentially affects phenotypic modularity and fluctuating asymmetry in generalist and specialist cactophilic Drosophila.

Modularity and developmental (in)stability have the potential to influence phenotype production and, consequently, the evolutionary trajectories of species. Depending on the environmental factors involved and the buffering capacity of an organism, different developmental outcomes are expected. Cactophilic Drosophila species provide an established eco-evolutionary model with well-studied ecological conditions, making them ideal for studying these phenomena. Here, we investigated how variations in larval diet and exposure to alkaloids on primary and secondary host plants affect the degree of integration/modularity and fluctuating asymmetry (a proxy for developmental instability) of wing shape in two sibling species with different degrees of specialization: D. buzzatii (generalist) and D. koepferae (specialist). Additionally, we compared the anterior-posterior modular configuration with a recently proposed proximal-distal modular configuration. Our results revealed greater independence among proximal-distal modules compared to anterior-posterior modules. Moreover, we observed sex-specific responses, with males exhibiting greater susceptibility to stressful environments than females. Each species showed a particular trait pattern across treatments: D. buzzatii showed increased integration and fluctuating asymmetry when reared in a nutrient-poor, alkaloid-rich secondary host, while D. koepferae displayed similar responses in novel environments characterized by double doses of alkaloids on the secondary host plant. These findings align with the generalist-specialist paradigm, suggesting that specialists may be challenged by novel environments, whereas generalists may be more affected by stressful conditions. Our study highlights the importance of considering each part of the proximal-distal wing axis independently, and the need to consider ecological-evolutionary history when investigating the relationship between complex phenotypic traits and environmental stress.

Black Soldier Fly (Hermetia illucens) Larvae as a Protein Substitute in Adverse Food Reactions for Canine Dermatitis: Preliminary Results Among Patients.

Can black soldier fly (BSF) larvae be a protein substitute for managing adverse food reactions (AFRs) in dogs, specifically those with dermatitis? We evaluated BSF larvae's safety, tolerance, and effectiveness as a novel protein source in dogs with AFRs. Sixteen dogs, including eight healthy controls and eight diagnosed with AFRs, were fed a diet containing BSF larvae for four weeks. Skin conditions, including dermatological lesions and Pruritus Visual Analog Scale (PVAS) scores, and gastrointestinal signs, including relevant clinical signs, stool consistency, and hematological and biochemical parameters, were monitored. No significant gastrointestinal side effects were observed. The control and AFRs groups maintained stable body weights, while stool consistency scores did not change significantly. Moreover, skin reaction data obtained before the study were collected through interviews with the owners. The mean PVAS scores in the AFRs group were significantly higher (p < 0.05) during the self-control period (6.0 ± 1.6) when compared with other periods. However, no significant differences (p > 0.05) were observed between the pre-study baseline (2.0 ± 1.1) and scores at 2 weeks (2.3 ± 1.5) and 4 weeks (2.4 ± 1.2) of feeding with BSF-based food, which indicated that BSF larvae did not exacerbate pruritic symptoms. Hematology and blood chemistry remained within normal ranges in all dogs, indicating no adverse effects on overall health. BSF larvae were well tolerated by AFR-affected and control dogs, with no adverse clinical outcomes. The findings suggest that BSF larvae may offer a better, sustainable alternative protein source for managing AFRs in dogs, particularly in those on hypoallergenic diets. Further long-term studies are needed to confirm these results and assess the broader implications of BSF larvae diets on canine health.

Nisin A Treatment to Protect Honey Bee Larvae from European Foulbrood Disease.

European foulbrood (EFB) is a bee larvae-specific infectious disease and the causative pathogen is Melissococcus plutonius. Broad-spectrum antibiotics have classically been used in many countries to control the pathogens; however, their use in apiaries was discontinued in several countries due to concerns regarding the health of bees and humans. Therefore, the development of alternative treatments for use in apiaries that are safe for bees and humans is essential. The present study examined the effects of nisin A supplementation using artificially reared honey bee larvae infected by M. plutonius strains. The results obtained showed that a non-purified nisin A product was toxic to honey bee larvae, while semi-purified nisin A by removing low-molecular-weight (< 3,000) chemicals was not lethal to honey bee larvae. A larval diet supplemented with the semi-purified nisin A significantly increased the survival rate of larvae infected by M. plutonius. The levels of nisin A required for this rescue differed between the M. plutonius strains used for infection, and 12.5 and 100µg/mL were required for strain DAT606 belonging to clonal complex 3 and strain DAT561 belonging to clonal complex 12, respectively. This beneficial effect was attributed to the antagonistic activity of nisin A against M. plutonius strains, and the levels of viable M. plutonius strains significantly decreased in the larval gut at the required concentrations. Due to the risks associated with the use of antibiotics in apiaries, food-grade nisin A is a promising alternative to control EFB.

Diet-induced plasticity modifies relationships between larval growth rate and post-metamorphic behavior and physiology in spadefoot toads.

It has frequently been hypothesized that among-individual variation in behavior and physiology will correlate with life history traits, yet the nature of these correlations can vary. Such variability may arise from plasticity in trait development, which can amplify or attenuate trait correlations across different environments. Using the Mexican spadefoot toad (Spea multiplicata), we tested whether relationships between larval growth rate and post-metamorphic behavior or physiology are influenced by a key mediator of developmental plasticity: larval diet type. Spea multiplicata larvae develop on two alternative diets, with slower growing omnivores feeding on detritus and faster growing carnivores consuming live fairy shrimp. We found that correlations between larval growth rate and post-metamorphic behavior and physiology differed by diet type. Among detritus feeders, faster growing larvae developed into juvenile frogs that were not only bolder but also had higher hypothalamic-pituitary-interrenal axis reactivity (an indicator of stress responsiveness) and longer telomeres, suggesting greater somatic maintenance. In contrast, among shrimp feeders - which exhibited faster growth overall - larval growth rate was less strongly correlated with juvenile behavior and physiology, indicating that a shift from omnivory to carnivory can attenuate trait correlations among individuals. Overall, our study suggests that developmental plasticity induced by different diet types can modify relationships between life history traits and individual behavior or physiology.

Intestinal flow and digestive parameters of Lutzomyia longipalpis larvae.

Lutzomyia longipalpis Lutz & Neiva, 1912 (Diptera, Psychodidae), is the primary vector of Leishmania infantum Nicole, 1908, the etiological agent of American visceral leishmaniasis. During their development, sandfly larvae pass through four instars, consuming soil particles enriched with microorganisms and decomposing organic material. In numerous insect species, the intestinal epithelium not only secretes digestive enzymes and absorbs digested nutrients but also carries out additional functions, such as regulating luminal pH and facilitating the absorption or secretion of ions and water. The transport of ions and water plays a crucial role in the establishment of a countercurrent flow responsible for recycling soluble digestive enzymes. This study aimed to explore specific aspects of digestion in L. longipalpis larvae that remain poorly understood. We measured the intestinal flow within the endoperitrophic space, which varied depending on the type of diet offered to the larvae, with an average total time of 191 min. Additionally, we demonstrated the countercurrent flow in L. longipalpis larvae. Finally, we showed that the production of digestive enzymes can be modulated by nutrient availability, particularly by the amino acids in the larval diet. The higher the amino acids concentration, the higher the trypsin activity. On the other hand, the aminopeptidase activity was poorly influenced by the amino acids concentration.

Impact of two larval diets on some biological aspects of 𝘊𝘩𝘳𝘺𝘴𝘰𝘮𝘺𝘢 𝘢𝘭𝘣𝘪𝘤𝘦𝘱𝘴 (Diptera: Calliphoridae)

Impact of two larval diets on some biological aspects of 𝘊𝘩𝘳𝘺𝘴𝘰𝘮𝘺𝘢 𝘢𝘭𝘣𝘪𝘤𝘦𝘱𝘴 (Diptera: Calliphoridae)

Comfort in stratification and trophic flexibility: argentine anchovy, Engraulis anchoita, larvae life traits in relation to their food sources

Fish larvae feeding success is crucial for adult recruitment, which affects both fisheries and ecosystem regulation processes. Engraulis anchoita is a species of great ecological and fishing relevance in the South-West Atlantic Ocean, with a wide latitudinal distribution and active spawning throughout the year and strongly associated with frontal areas. E. anchoita larvae have been described as exclusively feeding on small copepods and their early developmental stages. In this study, the diet, nutritional condition, and daily growth of E. anchoita larvae were estimated in different environmental scenarios in the South-West Atlantic Ocean. Carbon and Nitrogen stable isotopes analysis, otolith microstructure analysis, and RNA/DNA index determination were performed. The larval diet, which was evaluated based on the availability of potential prey, varied with respect to the water column stability. It was observed that the larvae tend to feed on microphytoplankton in stratified waters and on calanoid copepods in waters with a homogeneous vertical structure. The growth and nutritional condition indexes responded to ontogeny, presenting higher values at larger larval sizes. Growth indexes also responded positively to the stratified water column structure in comparison to the homogeneous one. The nutritional condition index was only explained by the size of the individuals. This study found that E. anchoita larvae had greater trophic flexibility than previously suspected, as they included microphytoplankton as the main food item under certain oceanographic conditions without negative impacts on their growth or nutritional condition.

A mass rearing method to aliquot and hatch Aedes mosquito eggs using capsules

The sterile insect technique (SIT) is a sustainable genetic control method to effectively suppress mosquito vector populations below sanitary and nuisance thresholds. The SIT requires a cost-effective production and release of radio sterilized insects of high and consistent quality and quantity. In this study, we report a new procedure to hatch, aliquot and introduce Aedes albopictus and Aedes aegypti larvae into larval mass rearing units using dissolvable vegetable capsules containing brushed eggs and larval diet. The results demonstrated that the egg brushing procedures, the opening of the hatching container and the presence of diet in the hatching solution increased Aedes eggs hatching success. The diet added during the hatching process decreased the dissolved oxygen (DO) concentration, which constituted the main stimulus for egg hatching success in both species. However, a DO reduction below 3 mg/l can effectively stimulate hatching in both species regardless of the deoxygenation method adopted. The capsule method produced similar hatching success without affecting larval survival and pupation rates in comparison with standard hatching procedures. The use of capsules eliminates intermediate laborious procedures for hatching, counting and transferring larvae into mass rearing trays with an expected improvement in production times and costs for Aedes SIT operational programs.

Exploring the metabolic changes of Ceratitis capitata Vienna 8 strain across three developmental stages through probiotic larval diet supplementation.

The Sterile Insect Technique (SIT) is revolutionizing pest control through its environmentally friendly approach, which involves rearing and sterilizing male insect pests using ionizing radiation and subsequently releasing them into the field to mate with wild females without producing offspring. Recent research has unveiled a groundbreaking enhancement in the quality of released Ceratitis capitata (medfly) males through the addition of probiotics to their larval diet. To thoroughly examine the impact of probiotic supplementation on the medfly larval diet, we conducted an in-depth analysis with GC-MS from medfly extract supplemented with probiotic Enterobacter sp. strain. The supplementation revealed a notable difference in the metabolomic signature compared to non-supplemented extract across all medfly life stages. We identified 37 known metabolites for all the stages, 12 of them were identified as biomarkers for the larval stage, 12 for the pupal stage, and 13 for the adult stage exhibiting crucial activities such as anti-bacterial, anti-fungal, and sexual and aggregation pheromone. These findings underscore the considerable potential of SIT combined with probiotic supplementation for enhancing sustainable pest control strategies worldwide.

No evidence for phenotypic condition-dependent ejaculate allocation in response to sperm competition in a seed beetle.

Sperm competition is known to favor the evolution of male traits that confer an advantage in gaining fertilizations when females mate multiply. Ejaculate production can be costly and the strategic allocation of sperm in relation to the sperm competition environment is a taxonomically widespread phenomenon. However, variation among males in their ability to adjust ejaculate allocation has rarely been explored. Here, we manipulated the phenotypic condition of male seed beetles, Callosobruchus maculatus, via larval diet quality and measured ejaculate allocation across varying levels of sperm competition manipulated using olfactory cues. Furthermore, we asked how strategic ejaculation was impacted by previous ejaculation. We found no variation in ejaculate allocation in response to experimentally manipulated cues to sperm competition. Ejaculate allocation was reduced by a male's previous mating history but was unaffected by the larval diets on which males were reared. We suggest that either male seed beetles are unable to adjust ejaculate size to the immediate competitive environment, or that sperm displacement strategies employed by males favor maximal investment at all mating events, especially when unmated females are infrequently encountered. As our study is one of few to examine condition dependence in strategic ejaculation, emphasis should be placed on future studies investigating this possibility across a wider range of taxa and animal mating systems.

Shared genetic architecture links energy metabolism, behavior and starvation resistance along a power-endurance axis.

Shared developmental, physiological, and molecular mechanisms can generate strong genetic covariances across suites of traits, constraining genetic variability, and evolvability to certain axes in multivariate trait space ("variational modules" or "syndromes"). Such trait suites will not only respond jointly to selection; they will also covary across populations that diverged from one another by genetic drift. We report evidence for such a genetically correlated trait suite that links traits related to energy metabolism along a "power-endurance" axis in Drosophila melanogaster. The "power" pole of the axis is characterized by high potential for energy generation and expenditure-high expression of glycolysis and TCA cycle genes, high abundance of mitochondria, and high spontaneous locomotor activity. The opposite "endurance" pole is characterized by high triglyceride (fat) reserves, locomotor endurance, and starvation resistance (and low values of traits associated with the "power" pole). This trait suite also aligns with the first principal component of metabolome; the "power" direction is characterized by low levels of trehalose (blood sugar) and high levels of some amino acids and their derivatives, including creatine, a compound known to facilitate energy production in muscles. Our evidence comes from six replicate "Selected" populations adapted to a nutrient-poor larval diet regime during 250 generations of experimental evolution and six "Control" populations evolved in parallel on a standard diet regime. We found that, within each of these experimental evolutionary regimes, the above traits strongly covaried along this "power-endurance" axis across replicate populations which diversified by drift, indicating a shared genetic architecture. The two evolutionary regimes also drove divergence along this axis, with Selected populations on average displaced towards the "power" direction compared to Controls. Aspects of this "power-endurance" axis resemble the "pace of life" syndrome and the "thrifty phenotype"; it may have evolved as part of a coordinated organismal response to nutritional conditions.

Microbial biopesticides are inhibited by honey bee royal jelly and in vitro larval diet

The interest in and use of biological materials in crop production is increasing globally at a rapid pace. In many cases, testing methods for conventional chemicals are applied to microbial-based biopesticides because specific microbial test methods are lacking. However, not all methods are easily transferred to microbial-based products. An evaluation was conducted to determine if OECD (Organization for Economic Co-operation and Development) Guidance Document No. 239 on honey bee larval toxicity could be adapted to microbial pesticides. In our study, five microbes, including B. pumilus, B. thuringiensis, B. velezensis, Paenibacillus larvae, and Ascophaera apis were grown on agar media and spotted with either honey bee in vitro larval diet or royal jelly. We observed that the honey bee larval bee diet and royal jelly did not inhibit the fungal honey bee pathogen Ascophaera apis, yet inhibited the growth of bacteria, including a known honey bee larval pathogen. This finding may make the test unreliable for certain biopesticides. The OECD is considering biopesticide-specific testing guidelines, and the EPA has indicated it to update itsbiopesticide bee test guidelines. However, additional research is needed to determine which options may be feasible and provide the best improvements.

Rearing fly larvae on various substrates: nutrient composition of larvae and frass.

Management solutions for waste in southern Thailand, such as fly larvae, are tested in a laboratory using different substrates and wastes from the Thai agricultural sector. The nutritional content of the immature stages of Musca domestica Linnaeus (Diptera: Muscidae) and Hermetia illucens (Linnaeus) (Diptera: Stratiomyidae) larvae, especially their protein and fat contents, makes them a potential animal feed. Laboratory strains of M. domestica and H. illucens were reared on selected substrates to examine how diet influenced their performance and nutritional composition. Waste from aquaculture, vegetables, and fruits in southern Thailand was examined for larval diet and showed promise as a rearing substrate for these insects. Musca domestica larvae reared on fishery waste achieved the highest larval weight and fat content, whereas H. illucens larvae reared on an aquaculture waste diet had the highest protein content. These findings imply aquaculture waste could be the best choice for large-scale fly larvae production, particularly as a protein feed additive.

The Effect of the Species Source of Muscle and/or Digestive Enzymes on the Utilization of Fish Protein Hydrolysates as a Dietary Protein Source in First Feed for Larval Walleye (Sander vitreus).

Fish protein hydrolysates used in larval diets have been prepared from a variety of fish species, with different enzymes used to hydrolyze the protein. This study's objectives were to determine the effect of the dietary inclusion of fish muscle hydrolysates obtained from species-specific muscle/enzymes-versus hydrolysates produced from muscle/enzymes of a different species-on the growth performance, survival, skeletal development, intestinal peptide uptake, and muscle-free amino acid (FAA) composition of larval Walleye (Sander vitreus). Eight protein products were obtained for this study, comprising an unhydrolyzed and hydrolyzed product from each combination of muscle/enzymes from Walleye and Nile tilapia (Oreochromis niloticus). Four diets were produced, and the dietary protein was provided in a 50/50 ratio of unhydrolyzed and hydrolyzed protein from the respective muscle/enzyme combination. Four groups were fed one of the corresponding formulated diets, and two groups of larvae, fed a commercial starter diet and Artemia, respectively, served as reference groups. Larval Walleye fed the diet containing protein produced with the species-specific muscle and enzymes had a significantly higher weight after the study-30% higher than any other group. A significant interaction effect between muscle and enzyme sources on the growth of Walleye larvae was observed. The species-specific combination also led to a significant increase in postprandial FAA and indispensable amino acid concentrations in muscle. No significant differences were observed between the hydrolysate-fed groups in survival, deformity occurrence, or peptide uptake. Each hydrolysate-based diet significantly reduced skeletal deformities and survival compared to the commercial diet. The results of this study suggest that species-specific muscles and enzymes produce a more optimal dietary protein source for larval fish than non-species-specific products. Further research should focus on improving the physical properties of the formulated diets to reduce possible leaching of hydrolyzed protein and improve the survival of fish larvae.

Feeding ontogeny: A new approach to predator–prey interactions

AbstractDiets of fish larvae may vary within populations and among species and are affected by larval prey availability and foraging capacity. We aimed to describe the diet of fish larvae based on empirical field observations, emphasizing the interaction and organization of the predator–prey network using Auchenipterus osteomystax as a species model. The network showed few interactions (low connectance and modularity) but a nested structure (some items that had fewer records tended to occur together with the most frequent ones), low complementary specialization (the proportions of ingested items tended to be equivalent) and a pattern of segregation (some items tended not to be consumed together) in the use of resources among individuals. Robustness was low when the removal of prey with a higher consumption frequency occurred. The correlation between morphological variables and network attributes was significant and positive for abundance and strength, while the correlation with nested rank was negative. The availability of suitable dietary resources is likely to be the key factor for success and survival in the early stages of development. With changes in morphology during larval development, A. osteomystax showed a generalist position in the network as its predation capacity increased. A new approach to trophic ecology studies of fish larvae incorporating network analysis may help explain the individual characteristics of larvae and assess the pattern of interactions in the population.

Effects of mulberry leaf enrichment with Lepidium sativum L. seed powder suspension on the economic parameters of Bombyx mori L

The phytochemicals of high nutritional and functional properties in Lepidium sativum L. (garden cress) seeds have nominated their seed powder (regardless of the concentration used) for enrichment of mulberry leaves in order to enhance Bombyx mori L. larval feeding, and consequently to gain ground in sericulture industry. As expected, B. mori larval feeding on L. sativum-enriched mulberry leaves showed not only a remarkable increase in mean values of certain economic parameters of B. mori, such as cocoon weight, cocoon shell weight, pupal weight, and egg yield, compared with the control group, but also showed a phenomenal increase in egg counts (on average, ca. 958–1256 eggs laid per female moth) and a significant increase in egg size (measured as egg surface area and egg volume). Male or female moth larval diet has significantly influenced the reproductive performance or fitness of both sexes of B. mori in terms of large-sized moths (measured as forewing, hind femur, and hind tibia lengths) and highly fecund moths (i.e., increased fecundity and spermatophore counts per female moth, and large-sized eggs). On the basis of B. mori female moth reproductive index, the female moths from L. sativum-fed larvae proved to have a lower reproductive index compared to their corresponding value for females of the control group, indicating more efficient utilization of larval resources for B. mori reproduction. Quantification of the three main physiological resources viz., protein, lipid and carbohydrate in the internal reproductive tract of B. mori female moths at death has nominated the female moth abdomens, or simply their bodies, as being a reasonable natural source of protein, lipid, and carbohydrate, to be involved in certain manufactures (e.g., pet feed formulations) instead of discarding them as a source of environmental pollution. Evidently, the L. sativum seed powder is of considerable interest because it remarkably improves the performance of such an economically important insect, B. mori. This is the first study for evaluating the efficacy of L. sativum seed powder in sericulture field to enhance B. mori productivity parameters.

Differential expression of fibroin-related genes in middle silk glands is induced by dietary differences in a strain-dependent manner in Bombyx mori

The silkworm (Bombyx mori) is a model organism for lepidopteran insects. It is an oligophagous insect that primarily feeds on mulberry leaves and has industrial use for the production of raw silk. The development of artificial diets has provided an alternative nutrient source for silkworms; however, one significant issue is that the production of cocoons is lower in silkworms reared on artificial diets compared with those reared on mulberry leaves. The differences in the silk gland in the late-stage fifth instar silkworm larvae, when silk synthesis is most active, between those raised on artificial diets and mulberry leaves, are unknown. In this study, we identified differences in the transcriptomes of the middle and posterior silk glands of fifth instar day five silkworm larvae reared on artificial diets compared with those reared on mulberry leaves using three strains: Daizo, Nichi01, and J137 × C146. We found that the silk-related genes fibrohexamerin (fhx), fibroin-light-chain (fibL), and fibroin-heavy-chain (fibH) in the middle silk gland, and ser1 in the posterior silk gland, were differentially expressed in a strain-dependent manner. In silkworms reared on artificial diets, fhx, fibL, and fibH in the middle silk gland were upregulated in Nichi01 and downregulated in J137 × C146, whereas ser1 in the posterior silk gland was upregulated in J137 × C146 compared with silkworms reared on mulberry leaves. Our results demonstrate that the diet and strain of silkworm larvae affect the expression of genes related to silk production in their silk glands during the late fifth instar stage.

Different Protein Sources of Larval Diet on the Rearing of Anastrepha fraterculus (Diptera: Tephritidae): Biological and Nutritional Analyses.

Anastrepha fraterculus (Diptera: Tephritidae) is considered an important pest in Neotropical countries. The laboratory rearing of this species should reproduce conditions in nature; thus, special attention is required to the nutritional quality of diets for larval development. Protein components (wheat germ) are costly and account for most production costs in lab insect rearing. In this sense, this work aimed to identify ingredients to replace wheat germ, without compromising diet quality for the lab rearing of A. fraterculus. We tested diets composed of whole rice flour, corn flour, and a mixture of whole wheat flour + soybean flour as substitutes for wheat germ as well as a raw wheat germ diet, considered the control. The protein sources used in the larval diet influenced the biological performance of both the larval and adult stages of A. fraterculus during six generations. The diet containing corn flour and wheat germ showed similar results in the different developmental parameters. The diet with rice flour also provided adequate biological development for A. fraterculus throughout its life cycle and was nutritionally similar to the control. As it is local product, rice flour can replace wheat germ (costly imported product) in artificial diets for A. fraterculus, reducing production costs by roughly 30% without compromising the biological and nutritional parameters of the insects. Faced with this, the rice flour can be considered suitable for the mass rearing of A. fraterculus in the laboratory.

Larval diet impacts black soldier fly (Diptera: Stratiomyidae) thermal tolerance and preference.

Thermal tolerance and preference are key parameters impacting agricultural production systems. In this study, the impact of larval diet on black soldier fly thermal tolerance and preference across life-stages and sexes was examined. Larvae were fed either a low-protein high-carbohydrate synthetic diet (i.e., P7C35), a high-protein low-carbohydrate synthetic diet (i.e., P35C7), or the Gainesville diet (i.e., C) as a control and reference. Our results demonstrate that the impacts of larval diet on black soldier fly thermal tolerance and preference could be stage and sex specific. The mean heat knockdown temperatures (HKT) ranged between 46.6 and 47.9 °C. Synthetic diets resulted in greater HKT and the difference decreased form larvae (e.g., ∼1 °C) to adults (e.g., ∼0.2 °C). The mean chill-coma recovery time (CCRT) ranged between 8.3 and 21.6 min. Not much differences were detected between diets, but CCRT became longer from larvae to adults. The mean thermal preference ranged between 13.6 and 29.5 °C. Larvae fed synthetic diets preferred much lower temperatures than the control diet. A bimodal distribution was observed for adults regardless of sex. Differences on body mass, lipid, and protein contents were detected among diets; however, more research should be done before any conclusions can be linked to their thermal traits. These findings highlight the importance of considering the ingredients and nutritional makeup of larval diets when optimizing temperature management protocols for mass production of black soldier flies. Conversely, specific diets can be developed to promote survival under extreme rearing temperatures.