Spatio-Temporal Distribution of Ceratothripoides claratris (Thysanoptera: Thripidae) on Tomatoes in Thailand

Ceratothripoides claratris Shumsher is one of themost important thrips pest of tomatoes in central Thailand. Hence we conducted studies to determine the intraand inter-plant distribution of C. claratris on tomatoes in two types of greenhouses, i.e., open-plastic and closed net house. The experimentswereconductedon thecampusof theAsian InstituteofTechnology inBangkok,Thailand. Both adults and larvae ofC. claratris showed foliage-biased distribution. Sex ratios of adultC. claratris did not signiÞcantly differ on ßowers and leaves, whereas on fruits males signiÞcantly outnumbered females.Onßowers, nodiurnal periodicity of occurrenceofC. claratriswasdetected.Generally, thrips infestationcommenced in the lowerparts of the tomatoplants andgradually spread to thehigher strata of the plants. Depending on the greenhouse type and the stem system thrips infestation differed signiÞcantly over time in the lower but not in the uppermost strata of the plants. In the net house, infestations ofC. claratris commenced oneweek after planting of the tomato seedlings. Soon after the peak in infestations, thrips numbers dramatically decreased. Estimates of TaylorÕs power showed that C. claratris had an aggregated distribution pattern on the foliage of tomato plants. The importance of these Þndings for future monitoring programs of C. claratris infestations on tomatoes is discussed.