Field response of sugarcane cultivars to sugarcane soldier fly, Inopus rubriceps (Macquart) (Diptera: Stratiomyidae)

Abstract Ten commercial sugarcane cultivars were planted in 10 replicate plots in each of three field trials in southern Queensland, to evaluate their response to the sugarcane soldier fly Inopus rubriceps . Trials were monitored for three harvests. Numbers of soldier fly larvae differed slightly between cultivars, but probably not enough to prevent the development of damaging populations. Weights of larvae were the same on all cultivars, suggesting that antibiosis was not involved. The effect of soldier fly on performance of cultivars in each trial was examined by regression of number of ratoon shoots and subsequent number and weight of mature stalks and crop yield on larval density during summer−autumn within each crop class. Where statistically significant relationships were detected in ratoons, each increase in soldier fly density of 100 m⁻² was associated with a yield reduction of 1.2−6.4 tonnes cane ha⁻¹, or 3−8% of the expected yield of uninfested plants. In most analyses, the slopes of regressions were the same for all cultivars, indicating no differential response to soldier fly infestation among the cultivars tested.     

Predation on Australian soldier fly,Inopus rubriceps (Diptera: Stratiomyidae), in pasture

Abstract

Invertebrate predation on the soil-living stages of Australian soldier fly may be a significant factor in the regulation of this pest of North Island grasslands. Laboratory and field experiments on larvae of Conoderus exsul and Agrypnus variabilis (Elateridae), adults and larvae of Thyreocephalus orthodoxus (Staphylinidae), and adults of Rhytisternus miser (Carabidae) suggest that all may influence the densities of soldier fly through predation on larvae and/or eggs. The functional responses of C. exsul, A. variabilis, and T. orthodoxus to soldier fly larval density are discussed. Selective removal of predators from pasture with insecticide showed that predation may account for up to 75% loss of the early instars of soldier fly.     

Growth and development of Australian soldier fly,Inopus rubriceps (Diptera: Stratiomyidae), in New Zealand

Abstract

Larvae of Inopus rubriceps (Macquart) were reared from eggs originating from spring and autumn adult emergence periods (1975–78), under both insectary and field conditions. Rate of development appeared to depend largely on temperature. Autumn-hatched larvae showed little growth for the initial 6 months, but then grew rapidly until the end of summer. Spring-hatched larvae also grew rapidly over summer, but their development slowed over winter. Year-to-year differences were found in larval survival, weight gain, and rate of development, and in subsequent adult emergence. Pest status appeared to be related to the cumulative yearly heat budget. Overall, larval survival was higher and growth and development were more rapid in the insectary than under field conditions. A male-dominant sex ratio was demonstrated.     

Inoculating poultry manure with companion bacteria influences growth and development of black soldier fly (Diptera: Stratiomyidae) larvae

The growth and development of black soldier fly, Hermetia illucens (L.), larvae fed chicken manure inoculated with bacteria isolated from black soldier fly larvae and associated larval feed was evaluated. Four strains of Bacillus subtilis were evaluated. B. subtilis strains S15, S16, S19, were isolated from the gut of black soldier fly larvae. B. natto strain D1 was isolated from the diet fed to black soldier fly larvae. These bacteria were added individually into nonsterile 200 g fresh hen manure at 10(6) cfu/g and homogenized. Treated manure was then inoculated with 4-d old black soldier fly larvae. Prepupal weight ranged from 0.0606 g in the control to 0.0946 g in manure treated with the S15 strain. Larval survivorship to the prepupal stage in all treatments ranged from 98.00 ± 2.65% to 99.33 ± 1.15%. Prepupal survivorship to the pupal stage ranged from 91.92 ± 1.87% to 97.95 ± 1.03%. Adult emergence from the pupal stage did not significantly (P < 0.05) differ across treatments and ranged from 98.95 ± 1.82% to 100.00 ± 0.00%. Adult body length resulting from the larvae in each of the treatments was significantly greater than those from the control. Longevity of adults did not differ significantly between treatments. Time from hatching to the development of the first pupa did not differ significantly across treatments; however, development time from hatching to 90% reaching the prepupual stage was significantly different between treatments and ranged from 29.00 ± 1.00 d to 34.33 ± 3.51 d. Development time from hatching to 90% reaching the adult stages was significantly different between treatments. Our results demonstrate that inoculating poultry manure with bacteria from black soldier fly larvae influences the growth and development of conspecific larvae feeding on the manure.     

Novel antibacterial peptides induced by probiotics in Hermetia illucens (Diptera: Stratiomyidae) larvae

There is a need to discover new therapeutic substances due to the emergence of deadly infectious diseases and various antibiotic resistance. We focused on the larvae that are utilized as a medical insect for the treatment of skin damage in Europe and America. This study was to investigate the pharmacological activities of novel antibacterial peptides isolated from Hermetia illucens larvae against the Klebsiella pneumoniae and Shigella dysenteriae. The larvae were immunized by probiotics (Lactobacillus casei) for 24 h. The hemolymph from the immunized larvae was fractionated through reverse‐phase chromatography. Peptides were purified using HPLC and the coomassie blue staining, and identified using Nano‐LC‐ESI‐MS/MS system. Antibacterial activities of the peptides were evaluated by turbidometric assay, liquid broth dilution assay, resazurin assay, and agar disk diffusion method. The minimum inhibitory concentrations (MICs) of the peptides were measured as 150 μg/mL through the turbidometric, liquid broth dilution, and resazurin assays. The peptides effectively inhibited their growth/proliferation as well as the survival rate of the tested bacteria. Furthermore, the immunized larvae exhibited overexpression of the peptides compared to non‐immunized larvae. These results demonstrate that the peptides induced by H. illucens exert strong antibacterial activity against Gram‐negative bacteria. The results suggest that the activation of the humoral immunity induced by immunization functioned to enhance the production of antibacterial peptides from the insect and their antibacterial properties. This study indicates the potential of the peptides produced from larvae as antibacterial peptide substance for the development of novel antibacterial drugs.     

Development of black soldier fly (Diptera: Stratiomyidae) larvae fed dairy manure

Black soldier flies, Hermetia illucens L., are a common colonizer of animal wastes. However, all published development data for this species are from studies using artificial diets. This study represents the first examining black soldier fly development on animal wastes. Additionally, this study examined the ability of black soldier fly larvae to reduce dry matter and associated nutrients in manure. Black soldier fly larvae were fed four rates of dairy manure to determine their effects on larval and adult life history traits. Feed rate affected larval and adult development. Those fed less ration daily weighed less than those fed a greater ration. Additionally, larvae provided the least amount of dairy manure took longer to develop to the prepupal stage; however, they needed less time to reach the adult stage. Adults resulting from larvae provided 27 g dairy manure/d lived 3-4 d less than those fed 70 g dairy manure. Percentage survivorship to the prepupal or adult stages did not differ across treatments. Larvae fed 27 g dairy manure daily reduced manure dry matter mass by 58%, whereas those fed 70 g daily reduced dry matter 33%. Black soldier fly larvae were able to reduce available P by 61-70% and N by 30-50% across treatments. Based on results from this study, the black soldier fly could be used to reduce wastes and associated nutrients in confined bovine facilities.     

Susceptibility of black soldier fly (Diptera: Stratiomyidae) larvae and adults to four insecticides

Dosage-mortality regressions were determined for black soldier fly, Hermetia illucens (L.), larvae fed cyromazine or pyriproxifen treated media. Cyromazine LC50 for larvae dying before becoming prepupae ranged from 0.25 to 0.28 ppm with dosage-mortality regression slopes between 5.79 and 12.04. Cyromazine LC50s for larvae dying before emergence ranged from 0.13 to 0.19 ppm with dosage-mortality regression slopes between 3.94 and 7.69. Pyriproxifen dosage-mortality regressions were not generated for larvae failing to become prepupae since <32% mortality was recorded at the highest concentration of 1,857 ppm. LC50s for larvae failing to become adults ranged from 0.10 to 0.12 ppm with dosage mortality-regression slopes between 1.67 and 2.32. Lambda-cyhalothrin and permethrin dosage-mortality regressions were determined for wild adult black soldier flies and house flies, Musca domestica L., and for susceptible house flies. Our results indicate that the wild house fly, unlike the black soldier fly, population was highly resistant to each of these pyrethroids. Regression slopes for black soldier flies exposed to lambda-cyhalothrin were twice as steep as those determined for the wild house fly strain. Accordingly, LC50s for the black soldier fly and susceptible house fly were 10- to 30-fold lower than those determined for wild house flies. The differential sensitivity between wild black soldier flies and house flies might be due to behavioral differences. Adult house flies usually remain in animal facilities with the possibility of every adult receiving pesticide exposure, while black soldier fly adults are typically present only during emergence and oviposition thereby limiting their exposure.     

黑水虻幼虫的耐饥力及饥饿幼虫复食后的生物学特性

【目的】旨在明确黑水虻Hermetia illucens幼虫的耐饥力及饥饿幼虫复食后的发育、生殖力等生物学特性,为评估饥饿对黑水虻后续发育的影响并指导生产实践提供依据。【方法】将不同日龄或不同体重黑水虻幼虫进行不同时长的饥饿处理,测定和分析其耐饥力与日龄、百头重的关系;对7日龄幼虫进行不同时长的饥饿处理后再复喂,测定不同饥饿时长对其预蛹出现时间、总预蛹率、预蛹重、成虫繁殖等的影响。【结果】黑水虻幼虫饥饿后的半数致死时间(LT₅₀)与日龄成指数关系,与体重呈线性相关。7日龄幼虫的耐饥力较强,LT₅₀超过了50 d,饥饿30 d时存活率仍然达到了95%。百头重小于0.5 g的个体,其LT₅₀小于30 d;百头重在2～2.5 g的个体,其LT₅₀在45～70 d。幼虫超过8日龄时或百头重超过4.5 g时,多数个体在饥饿5 d时就提前进入了后续发育阶段。7日龄幼虫饥饿40 d内复食,其预蛹率未受到影响,但预蛹重显著增加;短期饥饿(0～10 d)对其成虫产卵量无显著影响,长期饥饿(30～40 d)使其成虫产卵量显著下降;饥饿长达30 d以上时,卵孵化率也显著降低。【结论】本研究明确了不同体重或不同日龄的黑水虻幼虫都具有一定的耐饥力;饥饿幼虫复食后预蛹重显著增加。     

Wohlfahrtiimonas larvae sp. nov., isolated from the larval gut of Hermetia illucens (Diptera: Stratiomyidae)

A novel, Gram-negative, facultative anaerobic, motile and short rod-shaped bacterium, strain KBL006^T was isolated from the larval gut of Hermetia illucens, Black soldier fly. The 16S rRNA gene sequence of strain KBL006^T showed 96.4 % similarity to that of Wohlfahrtiimonas chitiniclastica S5^T. Strain KBL006^T grew optimally at 30 °C, at pH 8.0 and in the presence of 1–2 % (w/v) NaCl. Oxidase activity and catalase activity were positive. The major fatty acids were C_18:1 ω7c, C_14:0, and C_16:0. The major respiratory quinone was ubiquinone-8 (Q-8). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol, and two phospholipids. The G+C content of the genomic DNA was 45.2 mol%. Based on these polyphasic data, strain KBL006^T is considered to represent a novel species in the genus Wohlfahrtiimonas, for which the name Wohlfahrtiimonas larvae sp. nov. is proposed. The type strain is KBL006^T (= KACC 16839^T = JCM 18424^T).     

Hexanedioic acid from Hermetia illucens larvae (Diptera: Stratiomyidae) protects mice against Klebsiella pneumoniae infection

The antibacterial effects of larval extract from Hermetia illucens, commonly known as the black soldier fly, have been demonstrated in vitro. In this study, gas chromatography–mass spectrometry analysis identified the active compound within this larval extract as hexanedioic acid. The antibacterial effects of hexanedioic acid were investigated in mice infected with Klebsiella pneumoniae. After administration of hexanedioic acid, infected mice showed decreased lung bacterial loads and lower rates of body weight loss compared to those in the infection‐only control group. Based on lung bacterial loads, oral hexanedioic acid treatment showed better protection than intraperitoneal treatment. Histopathology confirmed that daily administration of hexanedioic acid for 10 days showed zero toxicity to the kidneys or livers of mice. Therefore, hexanedioic acid may be a novel antibacterial agent.     

New fossil Pachygastrinae from Mexican amber (Diptera: Stratiomyidae)

We describe the new genus Elektrothopomyia n. gen., with two new species E. saltensis n. sp. and E. tzotzili n. sp. as second and third fossil Pachygastrinae from the Mexican amber. These fossils from the Totolapa amber deposit confirm the presence of this group in Central America during the late Oligocene to middle Miocene period. Their exact affinities remain uncertain because of the current problems in the phylogenetic classification of these flies. These fossils are new elements of comparison between the entomofaunas of the Dominican and Mexican amber.     

Enhancement of fruit byproducts through bioconversion by Hermetia illucens (Diptera: Stratiomyidae)

Bioconversion is a biological process by which organic materials are converted into products with higher biological and commercial value. During its larval stage the black soldier fly Hermetia illucens is extremely voracious and can feed on a wide variety of organic materials. To study the impact of different fruit byproducts on the insect's growth, final larval biomass, substrate reduction, bioconversion parameters, and larval nutritional composition, 10 000 black soldier fly larvae (BSFL) were reared on 7.0 kg of one of three substrates (strawberry, tangerine, or orange) or on a standard diet as a control. The results highlight that BSFL can successfully feed and grow on each of these diets, though their development time, growth rate, and final biomass were differently impacted by the substrates, with strawberry being the most suitable. The lipid and protein contents of BSFL were similar among larvae fed on different substrates; however, major differences were detected in ash, micronutrient, fiber, fatty acid, and amino acid contents. Overall, the results indicate that fruit waste management through the BSFL bioconversion process represents a commercially promising resource for regional and national agrifood companies. Our study offers new perspectives for sustainable and environmentally friendly industrial development by which fruit byproducts or waste might be disposed of or unconventionally enhanced to create secondary products of high biological and economic value, including BSFL biomass as animal feed or, in perspective, as alternative protein source for human nutrition.     

Antibacterial effect of extracts of Hermetia illucens (Diptera: Stratiomyidae) larvae against Gram‐negative bacteria

Larvae of the black soldier fly, Hermetia illucens are well‐known fly larvae that inhabit many countries around the world. Antimicrobial agents derived from the larvae may be among the substances that are produced in the body for their survival. This study was carried out to identify the antimicrobial effects of H. illucens larvae that commonly inhabit animal waste and food waste. To evaluate the pharmacological effects of H. illucens larvae extracts, the larvae were extracted by various organic solvents, and their antibacterial effects were determined by antimicrobial methods, such as agar disk diffusion and turbidometric assays. The methanol extracts (ME) indicated antibacterial effects against the proliferation of Klebsiella pneumoniae, Neisseria gonorrhoeae and Shigella sonnei. However, antibacterial effects were not induced in Gram‐positive bacteria such as Bacillus subtilis, Streptococcus mutans and Sarcina lutea. The bacterial growth treated with ME was strongly inhibited from 20 mg/mL in a dose‐dependent manner compared with other extracts, and antibacterial activity gradually decreased after 24 h. Moreover, the minimal inhibitory concentration (MIC) values of ME against Klebsiella pneumoniae, Neisseria gonorrhoeae and Shigella sonnei for 12 h were measured as 44.74 mg/mL, 43.98 mg/mL and 43.96 mg/mL, respectively. These results demonstrate that ME of H. illucens larvae not only has antibacterial activity which strongly inhibits the growth and proliferation of the bacteria but also unique properties which effectively block the viability of the bacteria.     

Detection of antimicrobial substances from larvae of the black soldier fly,Hermetia illucens (Diptera: Stratiomyidae)

Maggots have become highly successful in the treatment of non‐healing wounds and multidrug‐resistant pathogen infections. The main objective of this study was to extract antibacterial substances from larvae of the black soldier fly, Hermetia illucens. To induce immune responses, we septically injured the larvae with a contaminated needle. Lyophilized H. illucens larvae were homogenized and extracted with acidic methanol. We examined the antifungal and antibacterial effects of the low molecular weight antimicrobial factors within the larval extract on the growth of a broad range of microorganisms, including Gram‐positive Staphylococcus aureus, methicillin resistant Staphylococcus aureus (MRSA), and Gram‐negative Pseudomonas aeruginosa. Furthermore, we isolated the anti‐MRSA substances from the larval extract using high performance liquid chromatography. These investigations revealed that the larval extract possessed a broad‐spectrum of antibacterial activity, demonstrating that secretions of H. illucens larvae prove useful in the fight against MRSA and can potentially be a source of novel antibiotic‐like compounds for infection control.     

Characterization of the molecular features and expression patterns of two serine proteases in Hermetia illucens (Diptera: Stratiomyidae) larvae

To investigate the molecular scavenging capabilities of the larvae of Hermetia illucens, two serine proteases (SPs) were cloned and characterized. Multiple sequence alignments and phylogenetic tree analysis of the deduced amino acid sequences of Hi-SP1 and Hi-SP2 were suggested that Hi-SP1 may be a chymotrypsin- and Hi-SP2 may be a trypsin-like protease. Hi-SP1 and Hi-SP2 3-D homology models revealed that a catalytic triad, three disulfide bonds, and a substrate-binding pocket were highly conserved, as would be expected of a SP. E. coli expressed Hi-SP1 and Hi-SP2 showed chymotrypsin or trypsin activities, respectively. Hi-SP2 mRNAs were consistently expressed during larval development. In contrast, the expression of Hi-SP1 mRNA fluctuated between feeding and molting stages and disappeared at the pupal stages. These expression pattern differences suggest that Hi-SP1 may be a larval specific chymotrypsin-like protease involved with food digestion, while Hi-SP2 may be a trypsin-like protease with diverse functions at different stages.     

Black soldier fly (Diptera: Stratiomyidae) larval heat generation and management

Mass production of black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), larvae results in massive heat generation, which impacts facility management, waste conversion, and larval production. We tested daily substrate temperatures with different population densities (i.e., 0, 500, 1000, 5000, and 10 000 larvae/pan), different population sizes (i.e., 166, 1000, and 10 000 larvae at a fixed feed ratio) and air temperatures (i.e., 20 and 30 °C) on various production parameters. Impacts of shifting larvae from 30 to 20 °C on either day 9 or 11 were also determined. Larval activity increased substrate temperatures significantly (i.e., at least 10 °C above air temperatures). Low air temperature favored growth with the higher population sizes while high temperature favored growth with low population sizes. The greatest average individual larval weights (e.g., 0.126 and 0.124 g) and feed conversion ratios (e.g., 1.92 and 2.08 g/g) were recorded for either 10 000 larvae reared at 20 °C or 100 larvae reared at 30 °C. Shifting temperatures from high (30 °C) to low (20 °C) in between (∼10-d-old larvae) impacted larval production weights (16% increases) and feed conversion ratios (increased 14%). Facilities should consider the impact of larval density, population size, and air temperature during black soldier fly mass production as these factors impact overall larval production.