Seasonal abundance and within plant distribution of melon thrips (Thysanoptera: Thripidae) on beans in Southern Florida

Abstract

The abundance of melon thrips. Thrips palmi Karny,
was investigated on bean crops planted at different times of
the year in six years in southern Florida. Abundance was high
on beans that were planted in Oct. 1991 and Jan. 1992; where
as abundance of 7". palmi was low on beans that were planted
in May, 1992. On beans planted in Oct. 1991, thrips populations
peaked on 13 Dec. 54 DAP. On the beans planted in Jan. 1992,
populations peaked on 27 Feb. and on 25 Mar., 37 and 62 DAP,
respectively. Population abundance was low in 1997,1998 and 1999; and increased again in 2000. In all plantings, larvae were
more abundant than adults. Numbers of females always exceeded those of males. Invariably, infestations began on the lower leaves, and with the progression of season, populations moved to the middle and upper leaves. With the exhaustion of food resources in the leaves, T. palmi populations moved to the flowers and fruits thereby causing serious yield loss of beans. This information will provide an insight about appearance of T. palmi in bean fields and their abundance in different times of the bean growing season. Within-plant distribution study provides key information about scouting beans for the presence of T. palmi.