Methyl palmitate does not elicit invasion of honeybee brood cells by Varroa mites

Since Varroa mites decide at some distance from the larva whether to stay on a bee or invade a cell, they may well use a volatile chemical to select a brood cell. A few aliphatic esters, predominantly methyl palmitate, have been claimed to be this volatile signal for the mites for two reasons. The mites respond to the esters in an olfactometer (Le Conte et al., 1989), and the levels of the esters in worker and drone larvae may explain that drone cells are attractive during a longer period and are invaded more frequently than worker cells (Trouiller et al., 1992). However, invasion itsclf appeared to be unaffected by application of methyl palmitate to brood cells. In addition, analysis of the volatiles emanating from attractive brood cells showed hundreds of components in the volatile blend, but in only 2 of 17 analyses a trace of methyl palmitate was found. Hence, there is no reason to believe that methyl palmitate is used as a signal for invasion by the mites.