Management of chilli thrips Scirtothrips dorsalis (Thysanoptera: Thripidae) on peppers by Amblyseius swirskii (Acari: Phytoseiidae) and Orius insidiosus (Hemiptera: Anthocoridae)

Abstract

Chilli thrips, Scirtothrips dorsalis Hood, recently established in southeast of the United States, poses an economic threat to a wide-range of ornamental and vegetable plants. In this study, we examined biological control of chilli thrips with a predatory mite, Amblyseius swirskii Athias-Henriot, and the insidious flower bug, Orius insidiosus Say. Laboratory tests showed that at equivalent rates, O. insidiosus was a more effective predator of adult thrips compared with A. swirskii, although the same trend was not observed with thrips larvae. At a rate of 20 predators per infested pepper plant, both predator species maintained ⩽0.5 thrips per leaf and <1% foliar damage after 5 weeks on all pepper varieties, compared with up to 13 thrips and >40% damage on control plants. Slightly less effective control was observed in a second study, where a reduced rate of predators (10 per plant) resulted in approximately 20% foliar damage, while damage was > 90% on control plants. Plants treated with O. insidiosus alone or in combination with A. swirskii had consistently fewer adult thrips and plant damage compared with A. swirskii alone. Furthermore, we observed different susceptibilities to thrips among pepper varieties, with damage lowest on ‘Trinidad perfume’ and ‘Brigadier hybrid’ compared with ‘Large red cherry’, and ‘Serrano’. Our results show that both predators were effective predators of chilli thrips on pepper and suggest that both species could be used in combination without decreased efficacy through intraguild predation.