Sex pheromone of the noctuid moth, Tyta luctuosa (Lepidoptera: Noctuidae), a candidate biological control agent of field bindweed

Laboratory studies were conducted to identify the sex pheromone of Tyta luctuosa (Denis and Schiffermuller), a Eurasian noctuid moth that has been imported and released to aid in control of field bindweed, Convolvulus arvensis L. Using gas chromatography-mass spectrometry, together with electroantennogram and windtunnel bioassays of male moths, two compounds, (Z)-9-tetradecenal and (Z)-11-hexadecenal, were identified as the major pheromone components. Whole-gland extracts contained these components, as well as two other major compounds, (Z) -9-tetradecanol and (Z)-11-bexadecanol. However, the two alcohols were not detected in airborne emissions of calling females. Ratios of Z9-14:ALD to Z11-16:ALD were markedly different for whole-gland extracts and airborne emissions (1:3 and 2:1, respectively). Also, although the total amount of the two compounds varied nearly eight-fold among individuals (22-167 ng, mean 75 +/- 56 ng [SD]) in gland extracts, the Z9-14:ALD/Z11-16:ALD ratio was relatively constant (0.3 +/- 0.15). On average, calling females released 94 ng of Z9-14:ALD and 45 ng Z11-16:ALD per hour, with a mean ratio of 2.2. In wind tunnel tests, 69% of males exhibited complete upwind flights and touched the stimulus source in response to a synthetic pheromone blend that mimicked the female-produced Z9-14:ALD/Z11-16:ALD airborne concentration and ratio, as compared with 82% and 50% in response to calling females and pheromone gland extracts, respectively. Tyta luctuosa adults are vagile, and both adults and larvae are cryptic in the field-factors that make recoveries of released insects unlikely. Therefore, our data will contribute to the development of a pheromone-based monitoring tool to help assess colonization and establishment of this potentially useful weed biological control agent.