Hymenopteran egg parasitoids of the genus Trichogramma are among the tiniest insects on Earth (< 0.5 mm in size, 8 µg) and are important biological control agents of moth pests. The existence of sex pheromones has been demonstrated in Trichogramma species, but none has yet been fully characterized. Here, we report absolute configuration, improved synthesis and behavioral activity of the sex pheromone of T. turkestanica, making it one of the smallest insects with a fully characterized sex pheromone. Enantioselective synthesis and chiral gas chromatography were used to determine the absolute configuration of the previously identified, stereochemically complex dienol (2E,4E,6S,8S,10S)-4,6,8,10-tetramethyltrideca-2,4-dien-1-ol and to newly establish the same stereochemistry for the corresponding diene (2E,4E,6S,8S,10S)-4,6,8,10-tetramethyltrideca-2,4-diene. In a 3:1 mixture of dienol and diene applied to two solvent-washed wasps (dummies), these compounds triggered attraction, arrestment, and courtship (“casting”) in males at doses, as little as 670 attograms per dummy. This pheromone could be studied to monitor T. turkestanica field populations, with the aim to improve the efficiency of biocontrol strategies.
Beek et al. (Thu,) studied this question.