Phytophagy and predatory behavior of Caliothrips phaseoli (Thysanoptera: Thripidae) on bean foliage discs with Tetranychus merganser (Acari: Tetranychidae) eggs

Abstract

Thrips (Thysanoptera: Thripidae) feed on leaf and flower tissue and some of them can be facultative predators. Caliothrips phaseoli Hood causes severe damage to different species of the Fabaceae family, mainly to Phaseolus vulgaris L. crops. The purpose of this research is to assess the change in feeding damage due to predation on Tetranychus merganser (Acari: Tetranychidae) eggs by the first and second larval stages of C. phaseoli on bean leaf discs, under laboratory conditions. Predation and damage were assessed through functional response and ordinal scale, respectively. The first and second larval stages of C. phaseoli exhibited a type II functional response. The second larval stage of C. phaseoli displayed shorter handling time and higher attack rate in comparison to the first instar. The first and second larval stages of C. phaseoli consumed 3.8 and 4.9 eggs of T. merganser per day, respectively. The second larval stage caused the highest damage (median = 3). The feeding damage of C. phaseoli was negatively associated to the number of eggs offered. The C. phaseoli larvae became more predatory than herbivorous when the number of eggs offered increased; therefore, C. phaseoli can be considered a facultative predator.