Toxicity of mint and eucalyptus extracts and some chemical insecticides on black legume aphid, Aphis craccivora (Hemiptera: Aphididae) and its predator, Hippodamia variegata (Coleoptera: Coccinellidae)

Abstract

Abstract Aphis craccivora also known as black legume aphid is a critical pests related to cowpeas, alfalfa, and grain legumes in Asia, Africa, and Latin America. Several different insecticides have been used to control this pest. The adonis ladybird, Hippodamia variegata is an active predators of this pest and can reportedly found all over the world. Aiming to reduce chemical insecticides, this study compares of the toxicity of the mint and eucalyptus extracts (Palizin®) (SL65%) and the chemical pesticides imidacloprid, pirimicarb, and spirotetramat onA. craccivora and its natural enemy H. variegata in the laboratory using leaf dipping method and the spraying technique. According to the results, the LC50 value of the botanical pesticide Palizin on A. craccivora was 50.017 ppm and on the H. variegata 54.606 ppm. Also, the mortality rate after 24 hours was as follows: Palizin used on A. craccivora at concentrations of 1250 ppm and 833 ppm caused 100% and 76.67% mortality, respectively while pirimicarb, with 70% mortality, performed better than spirotetramat (63.83% mortality) and imidacloprid (10% mortality). Furthermore, Palizin used on H. variegata at concentrations of 1250 ppm and 833 caused mortality rates of 66.68% and 63.33% respectively. Pirimicarb, however caused a mortality rate of 43.33% while spirotetramat and imidacloprid led to mortality rates of 10% and 100% respectively. Thus, it can be said that Palizin, at concentrations of 1250 and 833 ppm is suitable for farmers to use in controling A. craccivora while conserving part of the its predator population, H. variegata.