Competition in Western Flower Thrips Males: Effects of Density on Behavior

Abstract

Behaviour of males of Frankliniella occidentalis was examined within aggregations of different densities. Most male-male encounters resulted in immediate parting by males. The encounter position that resulted in most aggressive behaviour was when one male contacted another's thorax or abdomen with his legs and head. Although male density within aggregations ranged from <0.5 to >16/cm2, escalated aggressive interactions occurred only at lower densities. Behaviour of individuals within aggregations changed with increased encounter rates, turning rates and velocity as density increased. Within escalated fights between pairs of males, abdominal flicking occupied antagonists for longer than the grabbing/flicking phase.