Size-mediated activity and fecundity impacts of irradiation for sterile insect technique in Aedes aegypti

The proliferation of Aedes aegypti in California and around the world has led to increased research in effective and sustainable methods of control to stymie the transmission of arboviruses and reduce nuisance. Sterile insect technique (SIT) is actively being developed and explored for this species as a major part of integrated vector management toolkits in the face of insecticide resistance and administrative limitations on novel genetic methods. Though many types of SIT are possible, sterilization of males via x-ray irradiation is an established method that has proved effective in many systems including mosquitoes. Radiation dose must be carefully considered to ensure sterility while retaining survivorship and mobility to reach wild females after release, and competitiveness to have them actually mate and reduce the population. One understudied factor is the role of size variation in mediating the impacts of radiation. To examine this, we partnered with a California vector control district currently engaged in SIT and quantified the effects of two radiation doses that achieve generally good sterility on newly emerged adult males. Males from a local population were irradiated and then introduced to activity monitoring chambers which tracked their general movement until death, giving information on not only mortality rate, but also activity, which could be important for mating with females. Males were also released into competitive and non-competitive mating cages with females, whose egg production and hatch rate were compared with their size. Overall findings suggest that both male and female size play important roles in the SIT system.