Potential pesticide of three essential oils against Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae).
The alternative use of plant essential oils as pesticide, repellent and/or antifeedant has been emphasized as an important tool in integrated pest management (IPM), promoted by the growing interest in methods that fulfil requirements of efficiency, safety, selectivity, technically feasible and environmentally safe. The objective of this work was to determine the pesticide potential of essential oils of rosemary pepper (Lippia origanoides Kunth; Verbenaceae), citronella (Cymbopogon winterianus Jowitt; Poaceae) and lemongrass (Cymbopogon citratus [DC.] Stapf; Poaceae) to control fall armyworm (Spodoptera frugiperda [J.E. Smith]; Lepidoptera: Noctuidae). Ovicidal, larvicidal and pupicidal activity was evaluated with five dosages (0.1%, 0.5%, 1.0%, 2.5% and 5.0% v/v) and a negative control (neutral detergent at 5.0% v/v). Unhatched eggs, mortality of caterpillars and non-emerged adults were recorded using ovicidal and pupicidal percentage, and median lethal doses (LD50) to caterpillars. The essential oils showed insecticidal activity on the egg, caterpillar 3rd instars and pupae stages, highlighting the rapid action and high mortality rates caused by the L. origanoides essential oil, which registered, at lowest dosage, average 97.8% ovicidal activity and 81.3% pupicidal activity; in addition to LD50 on 3rd instar caterpillars, 0.001% by exposure and 0.033% by topical application. Essential oils of C. citratus and C. winterianus required longer periods to act and caused significant mortality on the three stages, registering LD50 0.008% and 0.159% for exposure, and 1.151% and 1.348% for topical application, respectively. Citronella oil caused behavioral changes in caterpillars, which reflected flight and aggressiveness. Therefore, these three essential oils can be an alternative for management of fall armyworm, with the potential to hinder and reduce its biotic potential.