Identification and field verification of sex pheromone from the mirid bug, Adelphocoris suturalis

Numerous species of mirid bugs (Hemiptera: Miridae) are phytophagous insect pests that damage economically important field and horticultural crops. In recent years, Adelphocoris suturalis has become a significant pest in transgenic Bacillus thuringiensis (Bt) cotton fields. We previously reported that virgin A. suturalis females attracted males in the field. In this study, we found that A. suturalis males are not attracted in Y-tube olfactometer bioassays to odors from either live nymphs or sexually mature virgin females whose ostioles of the metathoracic scent gland (MTG) are occluded with paraffin wax. However, males are significantly attracted to odors from adult virgin females when female abdomina are occluded with paraffin, indicating that female A. suturalis release sex pheromones only from the MTG. Volatile extracts from both sexes were collected and analyzed by gas chromatography–electroantennogram detection and gas chromatography–mass spectrometry. We identified (E)-4-oxo-2-hexenal (E4O2H), hexyl hexanoate (HH) and hexyl butyrate (HB) as major components and found that they elicited the largest EAD responses from antennae of males. Both E4O2H and HH were present in aeration extracts from females, while E4O2H was found in males. Capture of only males in field tests using synthetic compounds confirmed the activity of the identified sex pheromone candidates. In the field tests, a 10:1 ratio of the E4O2H and HH binary blend exhibited the highest efficiency in attracting male A. suturalis. Addition of HB to the binary pheromone blend to make a ternary blend did not increase trap catches. These results demonstrate that E4O2H and HH constitute the A. suturalis sex pheromone components.