A possibility of using synthetic analogues of juvenile hormone (juvenoids) to disrupt imaginal diapause of the apple blossom weevil, Anthonomus pomorum females was demonstrated. Out of three preparations tested (methoprene, fenoxycarb and W-328) methoprene and fenoxycarb appeared to be effective. Sensitivity to juvenile hormone analogues develops early after imaginal emergence (even before the female starts to feed) and lasts throughout the whole aestivo-hibernation dormancy. Although the juvenoids could stimulate the onset of oogenesis at any time during diapause, the propensity of the ovaries to form normal eggs developed only during hibernation part of the dormancy; in earlier stages of diapause accumulation of yolk was observed but matured eggs were not produced. Methoprene treatment caused marked increase of locomotory activity accompanied with decrease of dry weight, increase of water content, depletion of trehalose resources, decrease of cold hardiness and, finally, 100% mortality within four weeks in the weevils treated during their feeding or aestivation stages. Although similar changes were observed in the treated pre-feeding weevils, they later recovered and survived until next spring without apparent loss of cold hardiness. A possibility of designing a control method based on this principle is discussed and the results of small-scale field trials that support its plausibility are reported.
The aestivo-hibernation in central Greece of the aphidophagous ladybeetle Hippodamia (Semiadalia) undecimnotata (Schneider) (Coleoptera: Coccinellidae) was studied. H. undecimnotata is a multivoltine species in Greece. In the lowlands, all instars are abundant in spring, becoming scarce from July until the end of October and they are absent in winter. In June, most H. undecimnotata adults migrate to mountainous aestivo-hibernation sites. The duration of pre-oviposition period in females sampled monthly from the summits of the mountains Chlomo and Kitheron in central Greece and transferred to laboratory conditions of high temperature (25°C), long day (16L : 8D), and abundance of aphids (Aphis fabae), indicated that the H. undecimnotata females were in diapause during July and August. The diapause gradually terminated from late August to late October and was followed by a period of quiescence extending from November to March of the following year. During the summer diapause, arrested ovarian development was indicated by the undifferentiated state of the ovaries in all females. Males and females had enlarged fat bodies, and the median preoviposition period after the transfer to the laboratory was 92 days in early July and 64 days in early August. During the winter quiescence, arrested ovarian development was characterized by immature ovaries in females and, in some samples, by vitellogenic resorption in a few females. In winter, adults contained varying amounts of fat body reserves, and the median preoviposition period of females transferred to breeding conditions was 30 days in early November and 16 days in mid January.