POSTDIAPAUSE DEVELOPMENT AND MATING STATUS OF PEAR PSYLLA (HOMOPTERA,PSYLLIDAE) AFFECTED BY PEAR AND NONHOST SPECIES

Large numbers of winterform pear psylla, Cacopsylla pyricola Foerster, leave the pear orchard in the fall, overwinter in diapause in nonpear habitats, and return to pear orchards the following spring. Postdiapa use development of overwintering forms, including oogenesis and mating (indicated by spermatophore numbers in females), was more advanced in early spring for insects collected from pear than for those collected from apple, a nonhost but an important species for overwintering. The se results were confirmed by caging psylla on pear and apple in the fi eld and laboratory. Psylla were also caged on a number of ornamental s pecies in fall, and mortality and postdiapause development were monito red. Some insects, with the exception of those placed on a dead pear t ree, survived the winter on all plant species. Postdiapause developmen t on most species lagged behind that on pear. Psylla collected from pe ar trees on the orchard perimeter were often less advanced than those collected from the orchard interior, suggesting that psylla tended to colonize orchard edges. These effects were most pronounced in orchards and during years in which reentry rates were highest. Ovarian develop ment of psylla was similar in insects removed from yellow sticky traps and from clear sticky traps. Females removed from yellow traps had mo re spermatophores than those removed from clear traps on two sampling dates.