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Effects of strip-tilled cover cropping on the population density of thrips and predatory insects in a cucurbit agroecosystem

Manandhar, Roshan, Wang, Koon-Hui, Hooks, Cerruti R.R., Wright, Mark G.
Journal of Asia-Pacific entomology 2017 v.20 no.4 pp. 1254-1259
Carabidae, Crotalaria juncea, Cucurbitaceae, Frankliniella occidentalis, Orius, Thrips palmi, agroecosystems, autumn, biological control, cash crops, cover crops, field experimentation, ground vegetation, habitats, herbivores, pest management, population density, predatory insects, soil, spring, strip tillage
Strip-till cover cropping provides a structurally complex habitat (both diverse above ground vegetation and modified soil surface environment) in subsequent crops, which can contribute to suppressing herbivores in the cash crop, through either enhancing conservation biological control or altering herbivore behavior to the complex habitat. Two field trials (spring and autumn) were conducted to examine effects of strip-tilled cover crops (sunn hemp and marigold) on population densities of thrips (primarily, Frankliniella occidentalis and Thrips palmi) and generalist predators (Orius spp. and ground beetles, Aephnidius spp.) in cucurbit plantings. The results showed that strip-tilled cover crop treatments reduced thrips densities on cucurbit crops compared to the conventional monoculture. The strip-tilled treatments suppressed thrips densities more consistently in the autumn than in the spring trial. The reduced densities of thrips in strip-tilled cover crop plots were not attributable to the enhanced activity of predatory insects, but were most likely due to the disruption of host locating ability of thrips. Our study showed that the strip-till cover cropping could be an effective pest management technique for sustainable cucurbit production.