Potential use of Negramina (Siparuna guianensis Aubl.) essential oil to control wax moths and its selectivity in relation to honey bees

The utilization of synthetic insecticides is one of the most prevalent strategies used to control wax moth infestations, especially when the strength of bee colonies is weak. However, toxicity to bees and contamination of their products has been considered to be consequences of insecticide residues, increasing the risk of hazards to human health and to the environment. Here, we evaluated whether the application of Negramina, Siparuna guianensis Aubl., essential oil would be selective against the honey bees Apis mellifera L. without compromising the control of the wax moths Galleria mellonella L. and Achroia grisella F. The Negramina essential oil was chemically characterized and tested for insecticidal and repellent activities against A. mellifera as well as against both moth pests. The chemical composition of the essential oil revealed p-myrcene (79.7%) and 2-undecanone (14.6%) as the oil's main constituents. While G. mellonella and A. grisella were similarly susceptible to Negramina oil, the forager bees were five- to 10-fold more tolerant to the actions of the essential oil. Furthermore, the Negramina oil (0.30 mu g of essential oil/cm(2)) did not repel honey bee foragers but did exhibit repellent activities (0.08 mu g of essential oil/cm(2)) against the larvae and adults of both wax moth species. By exhibiting desirable levels of selectivity against A. mellifera and providing relevant control levels against wax moths, the application of Negramina essential oil represents a desirable tool to replace the use of synthetic insecticides against wax moths in weak honey bee colonies as well as in stored honey bee combs.