Seasonal Development of Leptopilina boulardi (Hymenoptera: Eucoilidae) and Its Hosts, Drosophila melanogaster and D. simulans (Diptera: Drosophilidae), in California

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Abstract
Laboratory and field studies conducted during 1982–85 examined seasonal development of Leptopilina boulardi Barbotin et al. and its fly hosts, Drosophila melanogaster Meigen and D. simulans Sturtevant. in northern California. Both fly species overwintered as long-lived fecund adults, presumably in a state of quiescence; no diapause was detected. In contrast, L. boulardi entered hibernal diapause as fifth instars within host puparia. In spring, reproductive activity of D. melanogaster and D. simulans resumed 2–3 months before reappearance of L. boulardi. Comparative developmental studies indicate that D. melanogaster and D. simulans have slightly lower thermal thresholds than their parasitoid (11.4 and 10.6°C, respectively, versus 12.8°C). and require significantly fewer degree-days (DD) to complete development from egg to adult (149 DD and 144 DD, respectively. versus 252 DD). These results indicate that the biological-control potential of L. boulardi is limited in northern California by the parasitoid's imperfect synchrony with seasonal occurrence and developmental cycles of its hosts.