Squash bug (Anasa tristis DeGeer) egg, nymph, and associated egg parasitoid fate: a reduced risk insecticide screening

The squash bug, Anasa tristis DeGeer (Hemiptera: Coreidae), is an important hemipteran pest of cucurbits, especially squash and pumpkin, and is typically managed with insecticides.  Little is known about the natural enemy complex in this system or its ability to suppress squash bug populations below pest levels.    Natural enemy complexes can be disrupted by broad-spectrum insecticide applications and the effects of narrow-spectrum insecticides on this system are unknown.  In order to learn more about this system and the effects of insecticides in it, egg masses of squash bug were collected from six different locations in Virginia and utilized in a reduced-risk insecticide screening.  Field collections have previously yielded multiple egg parasitoids in Virginia, of which, more than 95% were the native Platygastrid wasp (Hymenoptera: Platygastridae), Gryon pennsylvanicum Ashmead.  Egg masses were screened against reduced-risk insecticides and a common broad-spectrum material to test their effects on squash bug egg viability, egg hatch, and the emerging parasitoid wasps.  Insecticides screened were tested at field rates and include flupyradifurone, flonicamid, sulfoxaflor, pyrifluquinazon and lambda-cyhalothrin.  Using a Chi-square goodness of fit test, no significant effects of insecticide treatments were found on squash bug egg viability, egg hatch, or emerging parasitoid wasps.  These results do not suggest that any of the tested insecticides affected viability, egg hatch, or the parasitoids.  In the future, adult bioassays of the wasp may allow us to discern the effects of these and other insecticides on the adults of this natural enemy.