Soldier Larvae Research Articles

Long-read genome assembly of the Japanese parasitic wasp Copidosoma floridanum (Hymenoptera: Encyrtidae).

Copidosoma floridanum is a cosmopolitan species and an egg-larval parasitoid of the Plusiine moth. C. floridanum has a unique development mode called polyembryony, in which over two thousand genetically identical embryos are produced from a single egg. Some embryos develop into sterile soldier larvae precociously, and their emergence period and aggressive behavior differ between the US and Japanese C. floridanum strains. Genome sequencing expects to contribute to our understanding of the molecular bases underlying the progression of polyembryony. However, only the genome sequence of the US strain generated by the short-read assembly has been reported. In the present study, we determined the genome sequence of the Japanese strain using Pacific Biosciences high-fidelity reads and generating a highly contiguous assembly (552.7 Mb, N50: 17.9 Mb). Gene prediction and annotation identified 13,886 transcripts derived from 10,786 gene models. We searched the genomic differences between US and Japanese strains. Among gene models predicted in this study, 100 gene loci in the Japanese strain had extremely different gene structures from those in the US strain. This was accomplished through functional annotation (GGSEARCH) and long-read sequencing. Genomic differences between strains were also reflected in amino acid sequences of vasa that play a central role in caste determination in this species. The genome assemblies constructed in this study will facilitate the genomic comparisons between Japanese and US strains, leading to our understanding of detailed genomic regions responsible for the ecological and physiological characteristics of C. floridanum.

The Black Soldier Fly (Hermetia illucens) Larvae Meal Can Cost-Effectively Replace Fish Meal in Practical Nursery Diets for Post-Larval Penaeus vannamei under High-Density Culture

The black soldier larvae meal (BSFLM) has been the most extensively studied insect protein source in shrimp nutrition. However, both the availability and prices of BSFLM are still a constraint for its widespread use as an ingredient in animal feeds. The present study investigated the growth and economic performance of post-larval (PL) P. vannamei fed nursery diets with a progressive replacement of fish meal (FML) for BSFLM at 0, 25, 50, 75, and 100%. These replacements corresponded to a dietary inclusion (% of the diet, as-is) of FML and BSFLM of 16.50 and 6.33%, 11.00 and 13.04%, 5.50 and 19.74%, and 0 and 26.46%, respectively. A total of 102,647 shrimp at the age of PL15 with 2.7 ± 0.2 mg body weight (BW) were stocked in fifty 1.5 m3 tanks under 1369 PLs/m3 (2053 ± 33 PLs/tank) and reared for 42 days. Final shrimp survival (90.5 ± 7.6%), daily weight gain (14.7 ± 1.1 mg/day), and apparent feed intake (0.67 ± 0.03 g of feed per stocked shrimp) were unaffected by dietary treatment. The highest gained yield (791 ± 52 and 776 ± 38 g/m3) and final BW (621 ± 7.2 and 632 ± 7.2 mg) were attained when FML was replaced for BSFLM at 50 and 75% with the lowest at 0% (726 ± 34 g/m3 and 598 ± 8.1 mg, respectively). Shrimp fed diets with 0 and 100% replacement of FML exhibited the highest feed conversion ratio (1.25 ± 0.04 and 1.24 ± 0.08) compared to those fed a diet with 50% (1.16 ± 0.06). At a price of USD 2.00/kg, BSFLM demonstrated a favorable ROI (return of investment) when compared to FML, irrespective of the replacement level. With 25 and 50% replacement, BSFLM remained cost-competitive up to 3.50 USD/kg. At 75% FML replacement, there were no significant differences in ROI with a price range of 2.00 up to 3.04 USD/kg. At full replacement, ROI dropped significantly at a BSFLM price of 2.50 USD/kg and beyond. It can be concluded that FML can be fully replaced for BSFLM in well-balanced nursery diets for P. vannamei. Although the full replacement of FML for BSFLM was successfully accomplished, the competitive ROI was sustained only when the price of BSFLM did not exceed 3.04 USD/kg at its dietary highest inclusion of 19.74%. Further research may be necessary to fine-tune cost-effective inclusion levels of BSFLM to optimize the economic outcomes while considering the fluctuating prices of FML.

Antibiosis interaction of black soldier flies (Hermetia illucens) (Diptera: Stratiomyidae) with house fly (Musca domestica) (Diptera: Muscidae).

Black soldier fly (Hermetia illucens (Linnaeus, 1758)) larvae inhibit oviposition of house fly (Musca domestica Linnaeus, 1758) by releasing a semiochemical, although in some situations, inhibition is only partial. We hypothesized that there is a certain period in the life cycle of black soldier fly when it can cause antibiosis of the house fly. Choice and non-choice tests were used to separately examine the effectiveness of each developmental stage of black soldier fly (egg, larval (phase I, II, and III), prepupal and pupal stages) and crude extract of larvae on house fly oviposition. Tests using each developmental stage were compared with controls lacking black soldier fly. The effects of black soldier fly on the number of newly hatched house fly larvae were evaluated and there was a significant difference between the test and control in the number of eggs laid by house fly for all phases of the black soldier fly larval stage. Strong inhibition was found in some black soldier fly larval phases. Significant differences in the numbers of house fly eggs oviposited in food containers treated with crude extract were found when compared with a control, confirming that chemicals from black soldier fly larvae resulted in inhibition of oviposition of house fly. The results from experiment also indicated that chemicals from black soldier larvae influenced the number of house fly larvae newly hatched from eggs.

The effectiveness of liquid biofertilizer from waste bioconversion using black soldier fly larvae on the growth of arabica coffee seedlings

The organic waste treatment process using Black Soldier Larvae (BSF) produces liquid biofertilizer (LB) that contains functional microbes and macro and micronutrients that potentially can stimulate plant growth. The study aimed to determine the effectiveness of liquid biofertilizer from waste bioconversion by BSF on the growth of arabica coffee seedlings. The experiment used a randomized block design with 7 treatments, which consisted of: no treatment (control), 1.5% LB spraying, 3% LB spraying, 6% LB spraying, 3% LB watering, 6% LB watering, and 12% LB watering, with 4 replications and each replication containing 10 plants. All treatments were given once a month, to the 1-month-old seedlings. The test results showed that the application of LB significantly increased stem diameter and the number of leaves of Arabica coffee seedlings 4 months after application (MAA). In seedlings aged 4 MAA, spraying 6% LB resulted in the highest increase in stem diameter, while the highest number of leaves was obtained from watering 3% LB. Additionally, in 12 months old seedlings, Arabica coffee's highest fresh shoot weight was obtained by spraying 1.5% LB compared to other treatments.

Determination of protein content in single black fly soldier (Hermetia illucens L.) larvae by near infrared hyperspectral imaging (NIR-HSI) and chemometrics

The production of alternative proteins to meet the demand of a growing population has accelerated the growth of the market for edible insects. Black fly soldier (BFS) larvae (Hermetia illucens L.) have been widely studied globally due to their high content of fat, protein, and minerals, being mainly used for animal feed. Chemical analysis for determination of its composition is time consuming and laborious. In this work, we have developed predictive models based on Near Infrared Hyperspectral Imaging (NIR-HSI), Partial Least Square Regression (PLSR) and Support Vector Machine Regression (SVMR) to estimate the total protein content in single and intact BFS larvae. A variable selection step by interval PLS (iPLS) and genetic algorithms (GA) was implemented to improve regression model performance. In addition, BFS larvae hyperspectral images were explored using Principal Component Analysis (PCA), whose results showed the distribution of the different chemical compounds in the larvae. The PLSR and SVMR models reached RMSEP values of 1.57–1.66% and RPD values of 2.0–2.5, indicating a good approximate prediction capacity (% protein range 25.5–43.5%). Variables selected by iPLS obtained better regression models than variables selected by GA, based on the lower absolute error. Chemical maps displayed the heterogeneous protein distribution in single larvae and a batch of larvae. This manuscript demonstrates that NIR-HSI and chemometrics can be implemented as a fast screening method to estimate protein content in single BFS larvae.

Black Soldier Fly/Larvae: A Weapon for Solid Waste Management and Alternative Feed for Poultry and Aquatic Industries

In developing countries like India, the most unresolved threats present at our urban citizens are related to solid waste management. Even though various methods were practiced previously, due to various scenarios the degradation and disposal of waste has yet remained as a challenge. Thus, to overcome the present situation, Black Soldier fly/larvae (BSF/L) based waste disposal and management can be implemented as one of the main practices as it has been proved to degrade kitchen solid waste to organic waste within a few hours. These larvae after feeding on solid wastes like vegetable waste, agricultural waste and bio-waste mature into a complete fly after several stages of development. Simultaneously, late larval stage i.e. the pre-pupa can be also used as feed in poultry and fish industries. It has been reported that the BSFL can consume organic waste in larger quantities and the rate of degradation is estimated to be higher than any other species of their kind. Moreover, as the rate of reproduction of BSF is very high and provides maximum yield it makes waste management very productive and profitable with greater outcomes. The larvae of BSF used as poultry and fish feed consist of 70% of protein and other of carbohydrates, fats, micro and macronutrients thus providing all the beneficiary nutrients to produce high-quality eggs and meat without any dose of antibiotics and hormones. BSF can be an alternative for recycling and valuing agro-industrial by-products as well. This review explains about the health benefits of using BSF as feed in aquaculture and poultry. This article also explains about the environmental impacts of using BSF. Thus, reviewing all the benefits of the usage of black soldier Larvae/ fly, it can be considered as the next solution for solid waste management in urban India as it has been approved by FDA.

Effect of fish meal replacement by black Soldier Fly (Hermetia illucens) larvae meal on serum biochemical indices, thyroid hormone and zootechnical performance of laying chickens

This study was conducted to investigate the effects of fish meal replacement by black soldier larvae meal on biochemical parameters, thyroid hormone and productive parameters of egg-type chickens from day-old to 68 wk of age. A total of 480-day-old Isa Brown egg-type chickens were assigned to 4 dietary treatments with larvae meal to replace fish meal at 0% (T0:), 50% ( T 50 ), 75% ( T 75 ), and 100% ( T 100 ). Each treatment had 6 replicates of 20 birds. Fish meal was used at the 8% level as the control diet. Data were collected on feed intake, live weight, biochemical parameters, eggs production, serum triiodothyronine ( T 3 ), and thyroxine ( T 4 ). Results showed that there was a similarity in the feed intake of the birds across the treatments. Higher body weights and lower ( P < 0.05) feed conversion ratio ( FCR ) were recorded in the birds fed 100 and 75% larvae meal during the rearing period. Overall, egg production was similar in birds fed 100 and 75% larvae meal and significantly higher ( P < 0.05) as compared to other groups. Total protein, total cholesterol, and triglycerides, serum T 3 and T 3 /T 4 ratio increased significantly ( P < 0.05) with the increase in the level of larvae meal. It was concluded that fish meal can be replaced with larvae meal up to 100% in layer diet for improved body weights and egg production.

Effects of aeration rate and feed on growth, productivity and nutrient composition of black soldier fly (Hermetia illucens L.) larvae

Black soldier fly larvae (Hermetia illucens L.) are widely cultivated as bioconversion agents. These larvae are known to be highly sensitive to changes in the external environment, such as temperature and relative humidity. Therefore, a rearing hive equipped with an instrumentation system known as the Modular Fly Hive was designed to cultivate black soldier larvae. This study aimed to determine the effects of aeration rate (0 – 0.84 m3/s.) and feed type (coconut endosperm waste and soybean curd) on growth and productivity of black soldier fly cultivated in Modular Fly Hives as well as well as feed digestibility and nutrient composition of the larval biomass. Increasing aeration rate decreased the average temperature and relative humidity within the hives. The results showed that the larvae demonstrated a sigmoidal growth curve for all types of feed and the type of feed significantly affects the average wet weight and length of the larvae. The greatest dry biomass productivity (52.85 ± 3.85 g/m2/day) was observed when the larvae were cultivated using soybean curd residue with an aeration rate of 0.84 m3/s, while the lowest dry biomass productivity (35.27 ± 9.72 g/m2/day) was observed when the larvae were cultivated using coconut endosperm waste without aeration. Proximate analysis revealed that the larval biomass had total protein, lipid, ash and carbohydrate content in the range of 37.20 – 48.60%, 9.61 – 20.02%, 4.80 – 6.40%, 33.86 – 38.70%, respectively. Amino acid in the biomass were dominated by glutamic acid (11.11–12.30%), aspartic acid (8.25 – 10.35%), leucine (8.09 – 8.57%), and lysine (6.74 – 8.14%). Lipid isolated from the larval biomass were mainly composed of lauric acid (28.35–61.68%), linoleic acid (6.27 – 30.29%), palmitic acid (7.62 – 15.23%), and myristic acid (5.05 – 14.34%).

Partial defatted black solider larvae meal as a promising strategy to replace fish meal protein in diet for Nile tilapia (Oreochromis niloticus): Performance, expression of protein and fat transporters, and cytokines related genes and economic efficiency

Insect meal can be a promising nutrients source in aquafeed, replacing expensive, scarce or unsustainable foods however; molecular mechanisms behind its role on fish growth remain unknown. From this point, the impact of partial or total replacement of fish meal protein with defatted black soldier larvae meal (PD-BSLM) on Nile tilapia's performance, body composition, expression of genes related protein and fatty acids transporters and immunity and economic efficiency was evaluated. A total of 500 Nile tilapia (17.9 ± 0.3 g) was distributed into 4 groups: control fed basal diet with 10% fish meal; the other 3 groups were fed basal in which fish meal was replaced by 25, 50 and 100% of PD-BSLM for 12-weeks. The results described that dietary inclusion of PD-BSLM had no negative impact on Nile tilapia's growth rate, feed conversion ratio, protein utilization and nutrient digestibility even after 100% replacement. Body fat content was significantly decreased with increasing PD-BSLM levels. Amino acids analysis of fish body showed that replacement of fish meal with 100% PD-BSLM has a slight change on its lysine content. Interestingly, lysozymes, IgM and nitric oxide levels were significantly enhanced in group fed PD-BSLM at 100% replacement level. Transcriptomics profile of genes encoding amino acids (SLC3A1-SLC6A19) and peptides transporters (SLC15a1a-SLC15a1b-SLC15a2) revealed no negative effect in response to PD-BSLM. Moreover, mRNA expression of genes controlling fat transportation and metabolism (FABP-2, PPAR-α and PPAR-β) was up-regulated in groups fed higher PD-BSLM levels. Remarkably, mRNA expression of proinflammatory cytokines (IL-1β gene TNF-α) was down-regulated and anti-inflammatory cytokines (IL-10) was up-regulated at higher PD-BSLM levels. Therefore, our study reported that replacement of fish meal with PD-BSLM up to 100% had a positive modulating effect on the expression of protein and fat transporters that can explain a non adversely affected growth performance of Nile tilapia. Besides, the higher inclusion levels of PD-BSLM can boost immunity of Nile tilapia as well as increased the economic efficiency.

THE GROWTH PERFORMANCE OF NATIVE CHICKEN AT STARTER PERIOD AFFECTED BY BLACK SOLDIER FLY LARVAE FROM HOUSEHOLD WASTE MEDIA

This study was to evaluate the growth performance of native chicken at starter period affected by black soldier fly larvae (BSFL) from household waste. This study was used 120 DOC of native chicken, black soldier larvae from household waste and basal diet (EM 3000 kcal/kg and CP 19%). This study was used completely randomized designed contain 6 treatments with 4 replicates. The treatment at this study consists of P0 = control (commercial feed), P1 = basal diet, P2 = basal diet + BSFL and its media 5%, P3 = basal diet + BSFL and its media 10%, P4 = basal diet + BSFL and its media 15%, and P5 = basal diet + BSFL and its media 20%. The parameters of this study were feed intake, body weight gain and feed conversion. The results of this study showed that treatment of BSFL and its media had not significant effect on feed intake, body weight gain and feed conversion. Conclusion in this study was the BSFL and its media had positive effect at native chicken at starter period.

Study on Utilization of Black Soldier Fly Larvae (Hermetia illucens) as Protein Substitute in the Pellet Diet of Clarias gariepenus Fingerling

Fish farming faces the challenge of the high cost of feeds because of the cost of high-quality protein like fish meal required in food formulations. Therefore, the need for alternative protein sources is much needed. Black soldier larvae (Hermetia illucens) are alternative feed containing high protein. BSF larvae contain high protein levels (42.7% dry matter; DM). Fish diets should contain 32% to 45% protein content. Therefore, it can be a substitute for a fish meal. This study was conducted to investigate the effect of freshwater fish meal replacement with black soldier fly larvae meal (BSFLM) on the growth rate of Clarias gariepenus fingerling. The effect of freshwater fish meal replacement with black soldier fly larvae (BSFLM) was investigated. This study involved the cultivation of Clarias gariepenus fingerling given BSFLM and a commercial diet. The results showed a difference between the weight gains of C. gariepenus, which were 6.46g in BSFLM, while the commercial diet was 1.9g during 28 days of experiments. There was also no significant difference (p &lt;.05) in the mean weight gain, specific growth rate (SGR), and survival rate. Using BSFLM as an alternative source of protein in fish farming can reduce costs in the aquaculture industry without changing its quality.

Nano-CT imaging of larvae in the ant Pheidole hyatti reveals coordinated growth of a rudimentary organ necessary for soldier development.

The growth of imaginal discs in holometabolous insects is coordinated with larval growth to ensure the symmetrical and proportional development of the adult appendages. In ants, the differential growth of these discs generates distinct castes-the winged male and queen castes and the wingless worker caste. In the hyperdiverse ant genus Pheidole, the worker caste is composed of two morphologically distinct subcastes: small-headed minor workers and larger, big-headed, soldiers. Although these worker subcastes are completely wingless, soldier larvae develop rudimentary forewing discs that function in generating the disproportionate head-to-body scaling and size of soldiers. It remains unclear, however, how rudimentary forewing discs in soldier larvae are coordinated with other imaginal discs. Here we show, using quantitative nano-CT imaging and three-dimensional analyses, that the increase in the volume of the soldier rudimentary forewing discs is coordinated with larval size as well as with the increase in the volume of the leg and eye-antennal (head) discs. However, relative to larval size, we found that when the rudimentary forewing discs appear during the last larval instar, they are relatively smaller but increase in volume faster than that of the head (eye-antennal) and leg discs. These findings show that the rudimentary wing disc in soldier larvae has evolved novel patterns of inter-organ coordination as compared with other insects to generate the big-headed soldier caste in Pheidole. More generally, our study raises the possibility that novel patterns of inter-organ coordination are a general feature of rudimentary organs that acquire novel regulatory functions during development and evolution.

Apoptosis-mediated vasa down-regulation controls developmental transformation in Japanese Copidosoma floridanum female soldiers

Copidosoma floridanum is a polyembryonic, caste-forming, wasp species. The ratio of investment in different castes changes with environmental stressors (e.g. multi-parasitism with competitors). The vasa gene was first identified in Drosophila melanogaster as a germ-cell-determining factor, and C. floridanum vasa (Cf-vas) gene positive cells have been known to develop into reproductive larvae. Cf-vas seems to control the ratio of investment in C. floridanum larval castes. In this study, we identified environmental factors that control Cf-vas mRNA expression in Japanese C. floridanum by examining Cf-vas mRNA expression under competitor (Meteorus pulchricornis) venom stress; we treated the male and female morulae with M. pulchricornis venom. We also assessed the effects of multi-parasitism of Japanese C. floridanum with M. pulchricornis and found an increasing number of female soldier larvae. The results showed that several amino acid sequences differ between the Japanese and US Cf-vas. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) showed that Japanese Cf-vas mRNA is expressed in both male and female larvae and pupae, but mRNA expression decreases in adults. Cf-vas mRNA expression significantly decreased, while C. floridanum dronc (Cf-dronc) mRNA expression increased, in female morulae after M. pulchricornis venom treatment at 20 h and 0 h of the culture period, respectively. Females and males showed different Cf-vas or Cf-dronc mRNA expression after M. pulchricornis venom treatment. Therefore, M. pulchricornis venom could affect the ratio of investment in different female castes of Japanese C. floridanum by decreasing Cf-vas mRNA expression via apoptosis.

Black Soldier Fly Larvae Rearrange under Compression.

Thousands of black soldier larvae hatch simultaneously from eggs laid within rotting vegetation or animal carcasses. Over the next few weeks, they grow while compressed by both their surroundings and each other. When compressed, these larvae rearrange to reduce the forces upon them. How quickly can larvae rearrange, and what final state do they choose? In this experimental study, we use a universal testing machine to conduct creep tests on larvae, squeezing them to set volume fractions and measuring the time course of their reaction force. Live larvae come to equilibrium at a rate 10 times faster than dead larvae, indicating that their small movements can rearrange them faster than just settling. The relaxation of dead larvae is well described by stretched exponentials, which also characterize hierarchical self-avoiding materials such as polymers or balls of crumpled aluminum foil. The equilibrium pressures of live larvae are comparable to those of dead larvae, suggesting that such pressures are dictated by the physics of their bodies rather than their behavior. Live larvae perform fluctuations to actively maintain this equilibrium pressure. This ability to survive large pressures might have applications in the larvae-rearing industry, where both live and dead larvae are packed in containers for shipping.

Mass killing by female soldier larvae is adaptive for the killed male larvae in a polyembryonic wasp

Self-sacrifice is very rare among organisms. Here, we report a new and astonishing case of adaptive self-sacrifice in a polyembryonic parasitic wasp, Copidosoma floridanum. This wasp is unique in terms of its larval cloning and soldier larvae. Male clone larvae have been found to be killed by female soldier larvae, which suggests intersexual conflict between male and female larvae. However, we show here that mass killing is adaptive to all the killed males as well as the female soldiers that have conducted the killing because the killing increases their indirect fitness by promoting the reproduction of their clone sibs. We construct a simple model that shows that the optimal number of surviving males for both male and female larvae is very small but not zero. We then compare this prediction with the field data. These data agree quite well with the model predictions, showing an optimal killing rate of approximately 94–98% of the males in a mixed brood. The underlying mechanism of this mass kill is almost identical to the local competition for mates that occurs in other wasp species. The maternal control of the sex ratio during oviposition, which is well known in other hymenopterans, is impossible in this polyembryonic wasp. Thus, this mass kill is necessary to maximize the fitness of the female killers and male victims, which can be seen as an analogy of programmed cell death in multicellular organisms.

Effects of heat shock and ambient temperature on female soldier production in a polyembryonic parasitic wasp

AbstractLarval castes are well known in both sexes of polyembryonic parasitic wasps, in which sterile soldier larvae are clonally produced from a single egg and thousands of reproductive larvae develop into adults. The proportion of soldier larvae in Copidosoma floridanum is first determined genetically in both sexes but subsequently increases in females as a result of environmental disturbances, such as the presence of competitive parasitoids. Because temperature is the most influential environmental factor affecting ectotherms, we hypothesize that an increase in ambient temperature also affects the production of female soldier larvae. Conversely, we hypothesize that there would be no effect of temperature on the production of male soldier larvae. In the present study, we show that heat stress experienced by C. floridanum at an early stage in host development increases the number of female soldier larvae produced during the last instar stage of the host. We also show that rearing at extreme (high and low) temperatures induces an increase in the number of female soldiers produced. The effect of heat stress and ambient temperature on soldier production is found only in females, as is the response to heterospecific competitors. By contrast, no responses are detected in males for either heat stress or ambient temperature. The adaptive effect of these phenomena is not known, although the results of the present study imply the existence of a common physiological cascade that causes an increase in the number of soldier larvae in females.

The Potency of Black Soldier Larvae (Hermetia illucens L.) as a Source of Protein for Livestock Feed

Black Soldier fly larvae is an insect capable to convert organic waste into body biomass. The purpose of this research was to determine the productivity, mass balance of the consumption process, and content of protein and fat of prepupa which has a potency as a livestock feed. This research used 6-day-old larvae, they were fed with cassava skin that has been smoothed with a variety of feeding doses: 12.5; 25; 50; 100; and 200 (mg / larvae / day) with ratio of feed and water 2: 1. The results showed that the feeding of 200 mg / larva / day produced the best larval growth with biomass productivity of 1.54 mg / day, residue yielded of 67.1 mg / day. The organic waste was convertion into larvae biomass. In this study, approximately consumption process scale is feed successfully converted to biomass 2.77%, metabolism 6.98%, and 90.24% residue. Protein content is 25.7%. It can be concluded that the larvae are able to convert organic waste into high protein biomass and potentially being used as a livestock feed. This research acts a model to predict mass balance of substrates for feed. The benefit of this research is the science approach used in this study that can be used as a reference by researchers and the community to determine the biomass production of an organism.

Use of high hydrostatic pressure to inactivate natural contaminating microorganisms and inoculated E. coli O157:H7 on Hermetia illucens larvae.

A chemical and microbiological characterization on Hermetia illucens larvae was carried out as well as an inactivation study of natural contaminating microorganisms and inoculated E. coli O157:H7 in black soldier larvae by using High Hydrostatic Pressure (250 to 400 MPa, for 1.5 to 15 min). Hermetia illucens was mainly composed of proteins (46.49%, d.m.) followed by fat (37.88%, d.m.). Larvae had a high contamination load of Total Aerobic Mesophilic bacteria (AMB) (1.58x107 cfu/g) and Enterobacteriaceae (1.15x106cfu/g). The presence of pathogenic microorganism varied: no Listeria spp. were found, but Salmonella (1.15x106 cfu/g) and E. coli (7.08x105 cfu/g) were detected in the larvae extract. High Hydrostatic Pressure (HHP) was effective against natural contaminating yeasts and molds producing more than 5 log cycle reductions at 400 MPa for any of the times considered (2.5 to 7 min), but a low reduction of total microbial load was achieved. The inactivation level of larvae inoculated with E. coli O157:H7 varied. At 400 MPa for 7 min more than 5 log cycle reductions were achieved. Among the three inactivation models studied, the one that best described the inactivation pattern of the cells, according to the Akaike index, was the Biphasic model.

Copidosoma floridanum (Hymenoptera: Encyrtidae) Rapidly Alters Production of Soldier Embryos in Response to Competition.

Most social insects are free living and produce castes that develop in response to extrinsic environmental cues. Caste-forming polyembryonic insects, in contrast, are all endoparasitoids that form social groups inside the bodies of host insects. The best studied polyembryonic wasp is Copidosoma floridanum (Ashmead), which produces ∼3,000 clonal offspring that develop into two castes named reproductive and soldier larvae. Caste determination in this species is mediated by whether or not embryos inherit primary germ cells (PGCs). Prior results showed that C. floridanum increases the proportion of female soldier larvae it produces per host in response to other parasitoids like Microplitis demolitor. Here we show that caste ratio shifts occur through increased formation of embryos lacking PGCs. Our results further indicated that increased soldier production was a specific response to multiparasitism elicited by the chorion of M. demolitor eggs.

Genome methylation patterns across castes and generations in a parasitoid wasp.

Environmental influences shape phenotypes within and across generations, often through DNA methylations that modify gene expression. Methylations were proposed to mediate caste and task allocation in some eusocial insects, but how an insect's environment affects DNA methylation in its offspring is yet unknown. We characterized parental effects on methylation profiles in the polyembryonic parasitoid wasp Copidosoma koehleri, as well as methylation patterns associated with its simple caste system. We used methylation‐sensitive amplified fragment length polymorphism (MS‐AFLP) to compare methylation patterns, among (1) reproductive and soldier larvae; and (2) offspring (larvae, pupae, and adults) of wasps that were reared at either high or low larval density and mated in the four possible combinations. Methylation frequencies were similar across castes, but the profiles of methylated fragments differed significantly. Parental rearing density did not affect methylation frequencies in the offspring at any developmental stage. Principal coordinate analysis indicated no significant differences in methylation profiles among the four crossbreeding groups and the three developmental stages. Nevertheless, a clustering analysis, performed on a subset of the fragments, revealed similar methylation patterns in larvae, pupae, and adults in two of the four parental crosses. Nine fragments were methylated at two cytosine sites in all larvae, and five others were methylated at two sites in all adults. Thus, DNA methylations correlate with within‐generation phenotypic plasticity due to caste. However, their association with developmental stage and with transgenerational epigenetic effects is not clearly supported.