Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2011
Publication Date: 9/16/2011
Citation: Dogramaci, M., Arthurs, S.P., Chen, J., McKenzie, C.L., Irrizary, F., Osborne, L. 2011. Management of chilli thrips Scirtothrips dorsalis (Thysanoptera: Thripidae) on peppers by Amblyseius swirskii (Acari: Phytoseiidae) and Orius indidiosus (Hemiptera: Anthocoridae). Biological Control. 59:340-347. Available: doi:10.1016/j.biocontrol.2011.09.008 Interpretive Summary: Chilli thrips is an exotic invasive pest recently established in the southern United States and Caribbean. The pest has been documented to attack more than 150 hosts from at least 40 different plant families including a wide-range of ornamental and vegetable hosts. It has been estimated that chilli thrips could eventually cause between $3 and $6 billion crop yield loss annually in the US. In the present study we evaluate a commercially available predatory mite, singly and in combination with another potentially important insect predator, for biological control of chilli thrips on several different pepper varieties. We consistently found the predatory mite less effective against adult thrips but was more effective against thrips larvae than the insect predator. In contrast, the insect predator preyed upon adults and nymphs of the chilli thrips at a similar rate. Results of greenhouse tests showed that while both species of predator were effective on their own, the predator combination did not necessarily increase effectiveness compared with each species individually. We also noticed significant interactions between the predators and pepper varieties for reducing chilli thrips populations when reduced numbers of the predators were released onto plants and believe leaf morphology could play an important role in the success of predatory mites for controlling chilli thrips. In conclusion, the predatory mite and predatory insect are promising predators of chilli thrips and likely other thrips on a range of pepper varieties. Our results on the compatibility of both species are encouraging and suggest that evaluation of predator combinations under field conditions is warranted.
Technical 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 thrips adult compared with A. swirskii, although the same trend was not observed with thrips larvae. In greenhouse tests, both predator species were highly effective when released alone and also in combination on five different pepper varieties pre-infested by chilli thrips. At a rate of 20 predators per plant, all predator treatments maintained = 0.5 thrips per leaf and < 1 percent foliar damage after 5 weeks on all pepper varieties, compared with up to 13 thrips and >40 percent 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 15 percent foliar damage, while damage was > 90 percent on control plants. Plants treated with O. insidiosus alone or in combination with A. swirskii had consistently less numbers of thrips adults, larvae and plant damage compared with A. swirskii alone. Furthermore, we observed different susceptibilities to thrips among pepper varieties, with damage lowest on Trinidad perfume compared with Large red cherry, Serrano, Serrano del Sol and Brigadier hybrid. Brigadier hybrid had less damage than Large red cherry and Serrano.