An important parasitic threat to honey bees, the mite Varroa jacobsoni, is attracted to its major prey, drone larvae, by methyl and ethyl esters of straight-chain fatty acids, in particular methyl palmitate. These esters were extracted from drone larvae with n-hexane and were identified by gas chromatography-mass spectrometry. Their behavioral effect was evaluated with the use of a four-arm airflow olfactometer.

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The ripe fruit ofMorinda citrifolia, host plant forDrosophila sechellia is highly toxic for three closely related species (D. melanogaster, D. simulans, andD. mauritiana). Green and rotten fruits are not toxic for all species tested. Short fatty acids were found to be present in large quantities in the extract of the ripe fruit. The most abundant (octanoic acid) was tested pure for its toxicity in a dose-dependent manner;D. sechellia is five to six times more resistant thanD. melanogaster to octanoic acid. Octanoic acid alone seems to be sufficient to explain the toxic effect of the pulp. It is less abundant in the rotten fruit and absent in the green fruit.

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