Walnut‐Infesting Flies, <i>Rhagoletis suavis</i> , Have Higher Survival When Reared With Host Fruit Husk

ABSTRACT Plant‐infesting insects require specific environmental conditions to ensure successful development and survival. Rhagoletis suavis (Loew) (Diptera: Tephritidae) develops within and around their walnut host as larvae and pupae, despite the allelopathic qualities of juglone in walnut fruit. We investigated whether components of the walnut fruit affected fly survival by subjecting larvae to four developmental substrate treatments: vermiculite and water, vermiculite combined with ground dry walnut husk and water, vermiculite and walnut husk‐soaked water, and vermiculite combined with ground dry walnut husk plus walnut husk‐soaked water. We measured survival across three life stage transitions: from larval emergence to pupation, from pupation to post‐overwintering, and from post‐overwintering to adult eclosion. We showed that the use of ground walnut husk with water in the substrate environment yielded a higher rate of survival compared with control conditions. We also found that ground dry walnut husk had higher moisture retention and a lower pH, which may aid survival compared with the other substrate conditions that contained walnut. The results of this study give insight into our understanding of how the environmental conditions experienced by plant‐infesting insects during development, including host plant chemicals, moisture, and pH, can affect survival.