Greenhouse and field evaluation of essential oil formulations on Nilaparvata lugens Stal and their natural enemies

Abstract

Citronella and clove (CiC) and lemongrass and clove (LeC) mixtures, each at the ratio of 1:1, citronella, lemongrass, and clove oils and solution without EOs (blank) were tested. To determine the effect of the EOs on oviposition deterrent and mortality of N. lugens adults, the rice plants were sprayed with each solution, allowed to dry, then the seedling was kept by a plastic cage that had the top part covered with perforated cloth. Three pairs of N. lugens adults were introduced into the cage. The observation was conducted on the number of eggs laid and the mortality of adults. An experiment on the mortality of nymphs was carried out by spraying the rice seedlings containing 10 nymphs and caged as above. The field experiment was conducted by spraying the rice plants with those solutions. The formulas of CiC and LeC at the concentration of 10 ml/L deterred oviposition of N. lugens by 64.6 and 57.4% respectively. Both EOs caused mortalities in adults at 43.3% and nymphs of N. lugens as much as 60-64%. Those formulas applied twice a week were effective to control N. lugens with the value of efficacy 70.2 and 50.4% respectively and safe to natural enemies in the field.