Effects of fenoxycarb on ovarian development, spring fecundity and longevity in winterform pear psylla

Abstract

AbstractThe insect growth regulator fenoxycarb prompts ovarian development in diapausing winterform pear psylla, Cacopsylla pyricola (Förster) (Homoptera: Psyllidae). We applied fenoxycarb to caged psylla in September, November, and December to test whether premature ovarian development reduced overwintering survival, spring fecundity, or spring longevity. Fenoxycarb prompted ovarian development in all treated psylla, with the largest effects occurring in the September‐treated insects. Recovery of live psylla in spring was 46–95% in treated insects and 72–92% in controls; overwintered insects from the fenoxycarb treatments survived field temperatures below −20°C despite having had mature ovaries. Fecundity and longevity of psylla were the same in treated and untreated insects, indicating that overwintering with mature ovaries did not cause reduced spring egglaying capacity. Several treated insects each deposited over 1900 eggs and survived more than 120 days. Due to their more advanced development, treated insects had higher oviposition rates than controls during the first 5 days after removal from the field. The largest impact on spring fitness was due to the effects of fenoxycarb on egg hatch. Eggs deposited on clean foliage by September‐treated females were less likely to hatch than eggs deposited by controls, suggesting that fenoxycarb affected developing eggs within the female. Prospects for using fenoxycarb in fall to control pear psylla appear to be limited.