Nesidiocoris tenuis in Burkina Faso: Distribution, predatory capacity and insecticide sensibility

Abstract

Tuta absoluta (Lepidoptera: Gelechiidae) is a worldwide invasive insect species, considered a major pest of tomato. It has recently established in Burkina Faso, where chemical control remains the only affordable option to limit damages. Nesidiocoris tenuis (Hemiptera: Miridae) is commercialized as a biological agent to control this pest in other parts of the world. But very limited information exists on this predator in Burkina Faso. In this study, we first performed an insect survey in all agricultural regions areas of the country, and we found N. tenuis to be widely observed in all of them. Then, we performed two laboratory bioassays and demonstrated that all instars preyed on T. absoluta eggs, whether they were fed ad libitum or they had to actively forage for their prey. Because insecticide tolerant populations of T. absoluta were recently identified, we finally aimed at identifying agrochemicals that do not harm N. tenuis. We evaluated the toxicity of two synthetic insecticides, three bio-bacterial insecticides and eight plant extracts, all being active ingredients available on the local market. Most of them (i.e., abamectin, emamectin benzoate, spinosad, spinetoram) were highly toxic for both T. absoluta and N. tenuis. In contrast, Bacillus thuringiensis var. Kurstaki, neem oil, Cleome viscosa (Asian spiderflower), Ocimum basilicum (Basil) and Cassia occidentalis (Coffee senna) were compatible with N. tenuis while still controlling T. absoluta. Based on our results, we recommend the application of Bacillus thuringiensis to both control T. absoluta and which does not compromise the maintenance of N. tenuis populations.