Effectiveness of conservation biological control against the cotton aphid Aphis gossypii Glover in okra fields I. Attractiveness of beneficial hoverflies by some varieties or species of basil Ocimum basilicum L.

Abstract

Hoverflies are important natural enemies against aphids. Pollen and nectar provided from floral resources in agricultural fields are effective for conservation and enhancement of local hoverfly populations. We investigated some basil Ocimum basilicum L. variations, holy basil O. tenuiflorum L., buckwheat Fagopyrum esculentum Moench and Phacelia tanacetifolia Bentham from April to August in 2015 in order to select useful insectary plants for hoverflies. Based on the seasonally changes of coverages, the number of flowers and hoverflies, we concluded holy basil was suitable floral resources for adult hoverflies from May to July. Decrease of hoverflies after July might be caused by high temperature or their parasitoids.