Reproductive Development of Female Plum Curculio (Coleoptera: Curculionidae) in the Mid-Atlantic: Presence of Multivoltine Populations

Abstract

The plum curculio, Conotrachelus nenuphar (Herbst), is a key pest of pome and stone fruit throughout eastern and central North America. There are two strains of plum curculio, the univoltine ‘northern’ strain and the multivoltine ‘southern’ strain. Voltinism associated with populations located in the mid-Atlantic region has been unclear from historic records, with recent studies suggesting multivoltine populations. In studies conducted in West Virginia, female plum curculios obtained from emergence and screen traps and from samples of host tree canopies strongly indicate the presence of at least some multivoltine populations, based on an ovarian development bioassay. Two periods of active oogenesis were detected. The first occurred in early spring between late April and early May and represented overwintered females reaching sexual maturity. A second period of oogenesis was detected beginning in late June and continuing through early August. Based on degree day accumulations and known developmental rates of plum curculio, the mid-Atlantic is comprised, at least in part, of multivoltine populations. Fruit growers, therefore, must consider that plum curculio can pose a threat to tree fruit throughout the active growing season.