No abstract

There can be substantial negative consequences for insects colonizing a resource in the presence of competitors. We hypothesized that bacteria, associated with an oviposition resource and the insect eggs deposited on that resource, serve as a mechanism regulating subsequent insect attraction, colonization, and potentially succession of insect species. We isolated and identified bacterial species associated with insects associated with vertebrate carrion and used these bacteria to measure their influence on the oviposition preference of adult black soldier flies which utilizes animal carcasses and is an important species in waste management and forensics. We also ascertained that utilizing a mixture of bacteria, rather than a single species, differentially influenced behavioral responses of the flies, as did bacterial concentration and the species of fly from which the bacteria originated. These studies provide insight into interkingdom interactions commonly occurring during decomposition, but not commonly studied.

Black soldier flies, Hermetia illucens (L.) (Diptera: Stratiomyidae), are of particular interest for their applications in waste management. Feeding on decaying organic waste, black soldier flies successfully reduce manure in confined animal feeding operations of poultry, swine, and cattle. To optimize waste conversion in confined animal feeding operations and landfill facilities, it is imperative to optimize black soldier fly development. Unfortunately, black soldier flies only convert waste during their larval feeding stages and therefore it is of interest to optimize the nonfeeding stages of development, specifically, the postfeeding and pupal stages. The time spent in these stages is thought to be determined by the pupation substrate encountered by the postfeeding larvae. The objective of this study was to determine the effect different pupation substrates have on postfeeding development time, pupation time, and adult emergence success. Five pupation substrates were compared: wood shavings, potting soil, topsoil, sand, and nothing. Postfeeding larvae took longer to reach pupation in the absence of a pupation substrate, although reaching pupation in the shortest time in potting soil and wood shavings. The time spent in the pupal stage was shortest in the absence of a pupation substrate. However, fewer adults emerged when a pupation substrate was not provided.

The black soldier fly has shown great promise in addressing two environmental concerns: (1) waste management; and (2) protein supplementation for use as feed for livestock, poultry, and aquaculture. Thus, tremendous efforts have been placed on mass-production of the black soldier fly. Currently, little is known about the thermal tolerance limits of black soldier fly eggs and immatures. The objective of this study was to determine the lower temperature threshold for black soldier fly development. Development time, egg eclosion and adult emergence success were measured at 12, 16 and 19 °C. We determined that the lower threshold for egg hatch was between 12 and 16 °C, taking 15 days to hatch. Furthermore, we determined that the lower temperature threshold for larvae is between 16 and 19 °C with egg hatch in 7.75 days at 19 °C. Mean development time from egg to adult at 19 °C was 72 days.

1. It is a long-standing challenge to understand how changes in food resources impact consumer life history traits and, in turn, impact how organisms interact with their environment. To characterize food quality effects on life history, most studies follow organisms throughout their life cycle and quantify major life events, such as age at maturity or fecundity. From these studies, we know that food quality generally impacts body size, juvenile development, and life span. Importantly, throughout juvenile development, many organisms develop through several stages of growth that can have different interactions with their environment. For example, some parasitoids typically attack larger instars, whereas larval insect predators typically attack smaller instars. Interestingly, most studies lump all juvenile stages together, which ignores these ecological changes over juvenile development.2. We combine a cross-sectional experimental approach with a stage-structured population model to estimate instar-specific vital rates in the bean weevil, Callosobruchus maculatus across a food quality gradient. We characterize food quality effects on the bean weevil's life history traits throughout its juvenile ontogeny to test how food quality impacts instar-specific vital rates.3. Vital rates differed across food quality treatments within each instar; however, their effect differed with instar. Weevils consuming low-quality food spent 38%, 37%, and 18% more time, and were 34%, 53%, and 63% smaller than weevils consuming high-quality food in the second, third, and fourth instars, respectively.Overall, our results show that consuming poor food quality means slower growth, but that food quality effects on vital rates, growth and development are not equal across instars. Differences in life history traits over juvenile ontogeny in response to food quality may impact how organisms interact with their environment, including how susceptible they are to predation, parasitism, and their competitive ability. K E Y W O R D Scowpea weevil, juvenile ontogeny, phytophagous consumer, stage-structured population model | 627 HOLMES Et aL.

This study tested the effect of photophase duration on black soldier fly, Hermetia illucens (L.; Diptera: Stratiomyidae), development. Successful larval eclosion, development time and adult emergence were measured for individuals exposed to 0 h, 8 h, and 12 h of light, at approximately 27°C and 70% relative humidity. Accumulated degree hours (ADH) were calculated to correct for differences in temperature across treatments. Larvae successfully eclosed in all treatments, with larvae in 12 h light requiring 5.77% and 4.5% fewer ADH to eclose than larvae in 0 h and 8 h, respectively. Overall, larvae in 0 h required 39.34% and 37.78% more ADH to complete their development from egg to adult than larvae in 8 h and 12 h, respectively. The effect of photophase duration on juvenile development was largest in the post-feeding stage, and smallest in the pupal stage. Specifically, post-feeding larvae in 0 h required 80.02% and 90.08% more ADH to pupate than larvae in 8 h and 12 h, respectively, but pupae in 8 h required 9.63% and 7.52% fewer ADH to eclose than pupae in 0 h and 12 h, respectively. Lastly, larval mortality was significantly higher in 0 h, with 72% survivorship, and 96% and 97% in 8 h and 12 h, respectively. However, 17.8% of mortality in the absence of light is hypothesized to be a result of predation by Arachnidae and Blattidae. These data could prove valuable for optimizing industrial processes for mass-production of this species for use as alternative protein in feed for livestock, poultry, and aquaculture.

No abstract

Model systems have long been used by ecologists and evolutionary biologists to disentangle biological interactions. Bridging theory and nature, model systems have traditionally been used to address questions of community assembly, species interactions and persistence. For example, our basic understanding of competitive exclusion and coexistence among species comes from Gause's (1934) Paramecium experiments and Park's (1948) work on Tribolium flour beetles. Density-mediated effects on population dynamics were demonstrated in Nicholson's (1954) blowflies, and evolution and principals of natural selection were and continue to be studied in Drosophila, bacteria, guppies and many other vertebrate and invertebrate model systems (reviewed in Garland & Rose, 2009). Among these textbook examples of model systems are seed beetles Bruchinae. Bruchinae are a coleopteran subfamily within Chrysomelidae with more than 1,300 described species (Kingsolver, 2004). Seed beetles colonize legume seeds and are recognized for their usefulness in quantifying species interactions with respect to competition (Ishii & Shimada, 2008), reproductive interference (Kishi, Nishida, & Tsubaki, 2009), oviposition behaviour (Cope & Fox, 2002) and trophic interactions (Ishii & Shimada, 2010, 2012). Seed beetles are also used to study phenotypic plasticity and gene expression across environmental gradients (Kawecki, 1995), and in selection experiments to study host plant adaptations and