Larval diapause development and termination and some characteristics of cold hardiness in Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) were studied under field conditions in northern Greece. P. gossypiella overwintering larvae were sampled at 20 to 30 day intervals and subjected to two photoperiodic regimes at 20°C. In larvae kept under a long-day photoperiod (16L : 8D) diapause development was accelerated compared to those kept under a short-day photoperiod (8L : 16D). There was no difference in response to the two photoperiods after February. Mean number of days to pupation of P. gossypiella overwintering larvae decreased progressively through the sampling period, from November to April. Chilling is not a prerequisite but does accelerate diapause development. Supercooling points for P. gossypiella overwintering larvae ranged from -14 to -17°C with the majority dying after freezing.
This report summarizes a study designed to uncover any tendency towards hyperparasitic behavior in Brachymeria pomonae (Cameron), a parasitoid of pink bollworm (PBW) (Pectinophora gossypiella Saunders) imported from Australia to California for biological control of the latter pest species. Brachymeria pomonae hyperparasitized both Apanteles oenone Nixon (ca. 10% of pupae exposed) and Cardiochiles nigriceps Viereck (ca. 23% of pupae exposed), and all hyperparasitic offspring of B. pomonae were males. However, B. pomonae's aggressive primary parasitism of several lepidopterous hosts, together with the low hyperparasitism rates and the failure to produce hyperparasitic female offspring suggested that hyperparasitism is a facultative behavior in this parasitoid. Brachymeria pomonae caused substantial mortality in A. oenone and C. nigriceps as a result of ovipositional probing. Finally, it did not attack PBW nor A. oenone pupae if they were not enclosed in a PBW cocoon, but aggressively attacked the pupae of both when enclosed in PBW cocoons. The results are of significance because B. pomonae was a candidate for release against PBW in California. Because of its facultative hyperparasitic habit, no effort was made to release it from quarantine. The basis for this decision, including the uncertain impact that hyperparasitoids may have on biological control programs, is discussed.