Insights into the microbial ecology of the New World screwworm, Cochliomyia hominivorax, from wild collections and under mass-rearing for sterile insect releases.

Authors: Arp, Alex; QUINTERO, GLADYS - US Department Of State; SAGEL, AGUSTIN - US Department Of State; GONZALES, RAPHAEL - Copeg; Phillips, Pamela; Hickner, Paul

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2021
Publication Date: 1/20/2022
Citation: Arp, A.P., Quintero, G., Sagel, A., Gonzales, R., Phillips, P.L., Hickner, P.V. 2022. Insights into the microbial ecology of the New World screwworm, Cochliomyia hominivorax, from wild collections and under mass-rearing for sterile insect releases. Scientific Reports. 12. Article 1042. https://doi.org/10.1038/s41598-022-04828-5.
DOI: https://doi.org/10.1038/s41598-022-04828-5

Interpretive Summary: Sterile insect technique is a method of insect pest control that utilizes releases of large numbers of sterile insects to reduce successful matings of wild insects and thus reducing populations. Mass rearing insects for these programs can reduce fitness of the insects and may reduce their ability to successfully mate with wild insects. One aspect of insect ecology that is known to impact mating ability or overall fitness is the microbial community associated with the insect. Here we looked at how mass rearing changed the microbial community of the New World screwworm. Our findings indicate that domestication of this insect drastically changes it's microbial community. Additionally bacteria thought to be abundant based on culturing methods are not as prevalent. Future studies will be able to use this data to perform assays identifying the function of these bacteria, how stable they are across different populations, and how the differences might impact mate choice.

Technical Abstract: Insect population control through the sterile insect technique (SIT) is only possible if you can mass rearing large quantities of high-quality insects. Adaptation of insect stocks to rearing conditions and artificial feeding systems can have a multitude of negative effects such as inbreeding depression, reduced compatibility with wild strains, unintentional selection for traits that lower fitness after release, and an altered microbiome. Insect microbiomes can have many effects on insects ranging from a reduction in sex pheromones to death, thus understanding these systems is important for mass rearing and the performance of the sterile insect control programs. In this study we explored the microbiome of the New World screwworm, Cochliomyia hominivorax, in field collected and mass-reared flies used by the SIT program. Significant differences were observed between these treatments, with wild captured flies having a significantly more diverse microbial composition. Bacteria known to stimulate oviposition were found in both wild and mass-reared flies. Two bacteria of veterinary importance were abundant in wild flies, suggesting C. hominivorax is a potential vector of these diseases. Overall, this study provides the screwworm eradication program a platform to continue exploring the effects associated bacteria have on screwworm fitness.