Potential of using mineral oils for the control of the mosquito bugs Helopeltis theivora (Hemiptera: Miridae) in cashew plantations

Abstract

• Potentials of using an n C24 MO in controlling Helopeltis theivora were investigated. • n C24 MO application significantly reduced egg hatchability of H. theivora. • Oil extended pre-oviposition period and reduced H. theivora fecundity and longevity . • n C24 MO at 1% v/v can be used for H. theivora control in cashew plantations. This study investigated the influence of an n C24 mineral oil (MO) on some biological characteristics of a mosquito bug, Helopeltis theivora, reared on cashew under laboratory and greenhouse conditions. Aqueous emulsions of the oil were applied as sprays to eggs at four daily intervals after oviposition to assess impacts on egg hatch, and to cashew seedlings to assess adult longevity and female fecundity reared on the plants. Field applications were also carried out to assess the impacts of sprays on populations of the bug in a cashew orchard. The results of the laboratory study indicated that 1% (v/v) of the MO application reduced egg hatch when applied to eggs on cashew seedlings, in separate treatments, 1, 2, 3, and 4 days after oviposition (DAO). Egg mortality showed a negative linear correlation with egg maturity (DAO). The pre-oviposition period of adult females placed on sprayed cashew seedling, after deposits of 1% (v/v) sprays dried, was significantly prolonged. The longevity of males and females on dry oil-spray deposits was lower than on seedlings sprayed with water. The fecundity of females was also lower. Field sprays significantly reduced populations of the bug on mature cashew trees. Mixtures of MO and abamectin were more effective than oil alone. The results of the study indicate that mineral oils can be used to suppress populations of H. theivora in cashew plantations.