Taro Saito, Rosemarije Buitenhuis
Thrips parvispinus (Karny) is a tropical thrips species that recently spread across the world. Extensive plant damage caused by T. parvispinus results in serious losses for growers, for this species feeds mostly on young leaves and flowers. Among many host plants, peppers are readily attacked by T. parvispinus across its geographical range. Effective and sustainable control methods for T. parvispinus in pepper production are urgently needed. Among the biocontrol agents available in North America, Orius insidiosus (Say) and Anystis baccarum L. were chosen for this study because both species are known to establish in pepper crops and are able to kill all mobile life stages, including the adults, of other thrips species. We carried out comparative efficacy trials in the laboratory using sweet pepper leaf disks and in the greenhouse using potted sweet peppers. The laboratory trial showed that 1 adult female of O. insidiosus or A. baccarum can kill adult female T. parvispinus at a similar rate, with approximately 21 and 18 thrips out of 40 killed in 24 h, respectively. The greenhouse cage trial showed that releasing either adult female O. insidiosus or adult female A. baccarum at the rate of 1 per 2 plants resulted in successful establishment of the predator population and reduced T. parvispinus population by 80% compared to the untreated control. Further studies are needed to validate this finding in larger scale greenhouse trials without cages, including damage assessment and fruit yield data.