The role of some intrinsic and extrinsic factors influencing take-off and landingDavidson M, Teulon D New Zealand Institute for Crop & Food Research Limited, Private Bag 4704, Christchurch, New Zealand Thrips are weak fliers. After take off, thrips can be picked up by air currents flowing at strengths beyond their ability to fly against. Why do thrips launch themselves into such air currents? Likewise, what triggers them to drop out of the air currents? We have been investigating factors that may influence Western flower thrips¨ take off and subsequent landing. In a wind tunnel females starved for at least 4 hours were more likely to fly than those not starved. The age of female thrips did not affect the proportion to fly in a wind tunnel, however a larger proportion of older thrips (13 days old) landed on a yellow sticky trap than younger thrips (3 days old). The concentration of a volatile compound affected the proportion of thrips to fly in a wind tunnel, with fewer flying in the presence of 1 ml of p-anisaldehyde compared to 0.5 ml. Field trials were undertaken using water traps surrounding a central trap baited with a volatile compound known to elicit a positive response in New Zealand flower thrips or onion thrips. The highest numbers of thrips were recorded in the baited trap with decreasing numbers in unbaited traps positioned within 2 m downwind of the central trap. The implications of these results in relation to thrips¨ use of olfactory and visual cues, and thrips¨ dispersal are discussed.
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