Effect of Barometric Pressure on Flight Initiation by <I>Trichogramma pretiosum</I> and <I>Trichogramma evanescens</I> (Hymenoptera: Trichogrammatidae)

Abstract

Abstract The effect of barometric pressure changes on flight initiation of female Trichogramma evanescens Riley and Trichogramma pretiosum Westwood (Hymenoptera: Trichogrammatidae) was studied in a flight chamber over a 6-h period. Six different barometric pressure regimens were tested for their impact on flight initiation of both species: constant 975 and 1,025 mbar (stable regimens), and 50 mbar increase or decrease in pressure between 975 and 1,025 mbar either within 1 (rapid increase or decrease) or 6 h (slow increase or decrease). Both Trichogramma species did not respond to stable or slow changes in barometric pressure, but rapid barometric changes significantly reduced the flight initiation of females. The effect of rapid barometric pressure changes was almost immediate and independent of its direction, whether it was increasing or decreasing. The reduction in flight initiation was lifted rapidly when the barometric pressure became stable again, immediately for T. pretiosum and 1 h later for T. eva...