THRIPS (THYSANOPTERA) SEASONAL FLIGHT ACTIVITY AND INFESTATION OF RIPE STONEFRUIT IN CANTERBURY, NEW-ZEALAND

The seasonal flight activity and infestation of ripe peach, nectarine, and apricot fruit by thrips, especially the New Zealand flower thrips Thrips obscuratus (Crawford) (Thysanoptera: Thripidae) were investiga ted in a mixed stonefruit orchard during 3 seasons in Canterbury, New Zealand. Water trap samples indicated T. obscuratus adult numbers were low in spring (September and October), increased gradually during ear ly summer (November and December), peaked in midsummer (mid-January), and declined in late January, with a period of moderate to low numbers throughout late summer and autumn (February through May). Numbers wer e lowest in winter (June through August). Other common thrips species in water traps included onion thrips, Thrips tabaci Lindeman; grain th rips, Limothrips cerealium (Haliday); and Haplothrips niger (Osborn). T. obscuratus adults (almost all females), eggs, and larvae were commo n on ripe peaches, nectarines, and apricots. L, cerealium adults were found on ripe fruit in small numbers but few thrips of other species w ere found. T. obscuratus eggs, larvae, and adults were found on fruit up to 3 wk before harvest but were most numerous on ripe fruit. T. obs curatus numbers were highest on fruit of stonefruit varieties that rip ened during December and January, the time of peak seasonal flight act ivity, compared with varieties that ripened during February, March, an d April. T. obscuratus adults trapped in orchard blocks appear to have originated from outside the orchard. Factors important to the populat ion dynamics of T. obscuratus are discussed as well as economic implic ations.