Population dinamic of snap bean pests on four growing seasons and its influence on productive parameters

Abstract

Insect pests of snap beans in northern Paraná state - Brazil were monitored during four growing seasons: March - May, May - June, August - September, September - November. Adults of leafhopper (Empoasca kraemeri), whiteffly (Bemisia tabaci) and corn rootworm (Diabrotica speciosa) were monitored weekly using a cone trap. Leafhoppers nymphs were counted in mid height trifoliate leaves. The productive parameters evaluated in harvesting were: number of pods / plant; number of marketable pods; number of damaged pods divided in bent pods, empty pods or bored pods. Insect infestation were lower in August - September growing period, which yielded higher percent of marketable pods. The highest population of leafhopper occurred in March - May period, when the percent of curved pods were also the highest. Maximum population of whitefly occurred in early season of March - May growing period. Leaf beetle (D. speciosa) population did not surpass de damage threshold in any growing period, but was higher in March - May season.