Dose and Enantiospecific Responses of White Pine Cone Beetles, Conophthorus coniperda, to a-Pinene in an Eastern White Pine Seed Orchard
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The white pine cone beetle, Conophthorus coniperda, exhibited dose and enantiospecific responses to a-pinene in stands of mature eastern white pine, Pinus strobus, in a seed orchard near Murphy, North Carolina, USA. (-)-a-Pinene significantly increased catches of cone beetles to traps baited with (±)-trans-pityol. (+)-a-Pinene did not increase catches of beetles to pityol-baited traps and interrupted the response of beetles to traps baited with (±)-trans-pityol and (-)-a-pinene. Maximal attraction of cone beetles to pityol-baited traps was obtained with lures releasing (-)-a-pinene at a rate of 103 mg/day at 23°C. Lures releasing (-)-a-pinene at rates lower or higher than 103 mg/day resulted in reduced catches to traps baited with (±)-trans-pityol. The sex ratio in all catches was heavily male biased. Attraction of the clerid predator, Thanasimus dubius, to traps baited with (±)-trans-pityol increased significantly with the presence of a-pinene, irrespective of enantiomeric composition. Maximal attraction of T. dubius to pityol-baited traps occurred with devices releasing (-)-a-pinene at the highest rate tested, 579 mg/d at 23°C a sub optimal rate for cone beetles.