Reproductive output and other adult life-history traits of black soldier flies grown on different organic waste and by-products.

The interest in mass-rearing black soldier fly (Hermetia illucens) larvae for food and feed is rapidly increasing. This is partly sparked by the ability of the larvae to efficiently valorise a wide range of organic waste and by-products. Primarily, research has focused on the larval stage, hence underprioritizing aspects of the adult biology, and knowledge on reproduction-related traits such as egg production is needed. We investigated the impact of different organic waste and by-products as larval diets on various life-history traits of adult black soldier flies in a large-scale experimental setup. We reared larvae on four different diets: spent Brewer's grain, ground carrots, Gainesville diet, and ground oranges. Traits assessed were development time to pupa and adult life-stages, adult body mass, female lifespan, egg production, and egg hatch. Larval diet significantly impacted development time to pupa and adult, lifespan, body size, and egg production. In general, flies reared on Brewer's grain developed up to 4.7 d faster, lived up to 2.3 d longer, and produced up to 57% more eggs compared to flies reared on oranges on which they performed worst for these traits. There was no effect of diet type on egg hatch, suggesting that low-nutritious diets, i.e. carrots and oranges, do not reduce the quality but merely the quantity of eggs. Our results demonstrate the importance of larval diet on reproductive output and other adult traits, all important for an efficient valorisation of organic waste and by-products, which is important for a sustainable insect-based food and feed production.

Rodent scavenging of pig remains potentially increases oviposition sites for primary colonizers.

The feeding of vertebrate scavengers on animal remains has been noted for at least 30 years in relation to the creation of postmortem artifacts. However, the subsequent impact on other necrophagous arthropods, which interact with these remains has not been well documented. Herein, we report a rodent (Rattus spp.) feeding event that altered a perimortem wound beneath the jaw of a decomposing swine carcass. Point trauma such as this has been cited as insufficient for insect colonization; however, the resulting enlargement of the wound due to scavenger feeding has the potential to serve as an oviposition site where colonization would typically not be expected otherwise (i.e., in the absence of a wound or the presence of a small wound such as point trauma). In fact, colonization was observed surrounding the site of scavenger alteration. If scavenger artifacts (e.g., postmortem alteration of remains by feeding) are not identified appropriately and recognized for the effects they may have on necrophagous arthropods then associated assessments in forensic investigations could be affected.

Optimizing a Dual-Choice Cube Olfactometer Design for Measuring Adult Secondary Screwworm (Diptera: Calliphoridae) Attraction to a Resource.

Detecting and locating a carrion resource is critical for the reproduction of necrophagous insects and initiating forensically important timelines. Blow flies (Diptera: Calliphoridae) primarily use olfactory cues in the form of volatile organic compounds to locate a suitable resource. Factors governing detecting and locating a resource have been studied using various behavior assays with modifications to suit the experiment design, such as the dual-choice cube olfactometer, which was examined in the current study. Systems optimization ensures biologically relevant and consistent results across replicates. In this study, two responses were measured: 1) leaving cube for either control or treatment and 2) choice between control and treatment. Phenotype (e.g., male, non-gravid, gravid) and total blow fly, Cochliomyia macellaria (Fabricius) (Diptera: Calliphoridae), number to respond were measured. Four parameters were assessed for their impact on response: 1) adjustment time in cube before trial, 2) trial length, 3) sugar/water presence, and 4) screening type in arms. Approximately, 70% of all phenotypes responded to liver with the 30-min adjustment period where only 50% responded with other adjustment periods. Trial length had a significant impact on response (35% increase in the 8 h trial compared to shorter durations); however, significant response to treatment was lost by increasing trial length. The presence of sugar/water decreased gravid and non-gravid response by 35% but did not impact males. Screening had no influence on overall or treatment response. Data indicate experiment design impacts fly response. Future studies should optimize parameters for their given fly population prior to initiating experiments.