Trophic Diapause in the Tropical Coccinellid Harmonia sedecimnotata (Fabr.) (Coleoptera, Coccinellidae): Induction and Reactivation

摘要

Food deficiency slows down the oocylc maturation in ovipositing females of Harmonia sedecimnotata. However, trophic reproductive diapause, characterized by cessation of oogenesis at the stage of the oogonia maturation, can be induced only by a complete lack of protein-rich food (aphids). Reactivation from the trophic diapause is possible only if protein-rich food becomes available again, irrespective of its quantity; the amount of food affects only the number of eggs laid. Despite numerous examples of the trophic factor affecting the diapause and even indications that it might influence the manifestations of the photoperiodic response, trophic diapause in insects remains the least studied (Tauber el al., 1986; Danks, 1987; Zaslavskii, 1996; Zaslavskii and Vaghina, 1996). Response to food is usually regarded as irregular and secondary, having a merely modifying effect on the photoperiodic response. However, some of the recent studies indicate that trophic response is signal and very accurate (Zaslavskii et al., 1998).