Evaluation of Euseius gallicus as a biological control agent of western flower thrips and greenhouse whitefly in rose

Euseius gallicus is a new phytoseiid species recently described from southern France that has shown potential as a biocontrol agent for thrips and whitefly in rose, if pollen is supplied as an additional food source. To investigate if the use of E. gallicus provides improved thrips and whitefly control, we conducted laboratory experiments examining the biology of E. gallicus and a semi-field experiment comparing the biological control efficiency of E. gallicus with that of Amblydromalus limonicus and Amblyseius swirskii, two phytoseiid species commonly used for biological control of thrips and whitefly in roses. Euseius gallicus had high oviposition rates on Typha latifolia pollen (3.9 eggs/day) and on young whitefly eggs (3.6 eggs/day). Oviposition on first instar Frankliniella occidentalis larvae was lower (1.5 eggs/day). Euseius gallicus predated 2.6 first instar thrips larvae per day; however, predation of thrips larvae was nearly zero when T. latifolia pollen was offered as a supplementary food source. Euseius gallicus females did not enter diapause under short-day conditions, and juvenile development was completed at 13°C. When released in combination with T. latifolia pollen on roses in the semi-field trial, E. gallicus developed the largest population of the predatory mites tested; however, despite reducing the whitefly population, it had no control effect on the thrips population.