PEAR THRIPS TAENIOTHRIPS INCONSEQUENS (THYSANOPTERA, THRIPIDAE) LIFE-HISTORY AND POPULATION-DYNAMICS IN SUGAR MAPLE IN PENNSYLVANIA

The pear thrips Taeniothrips inconsequens (Uzel) was sampled for four years in a small sugar maple Acer saccharum plantation in Centre Count y, Pennsylvania, USA. The life cycle of T. inconsequens was univoltine with the main period of emergence and flight from late March to mid M ay. Adults, eggs, and first and second instar larvae were associated w ith sugar maple budburst and early leaf development from late April to late May. Larval drop occurred from mid to late May. Mature second in star larvae, propupae, pupae and adults spent from June to March in th e ground; development from larva to adult occurred between September a nd November. From March to May most (usually >90%) thrips adults and l arvae sampled were T. inconsequens. No T. inconsequens males were foun d. In soil samples taken in spring, summer and autumn T. inconsequens were found to a depth of 50 cm but over 87% were in the top 20 cm. Alm ost no T. inconsequens were found in the litter layer. Large variation s in T. inconsequens adult emergence and larval drop were recorded. Th e most important contributing factors in fluctuations of T. inconseque ns populations were the length of sugar maple budburst, the degree of synchrony between thrips emergence and sugar maple budburst, and the o ccurence of sugar maple flowering.