DIURNAL FIELD PATTERNS OF HONEYDEW SUGAR SECRETION BY BEMISIA-ARGENTIFOLII (HOMOPTERA, ALEYRODIDAE) NYMPHS ON COTTON

Honeydew secretion by nymphal field populations of silverleaf whitefly , Bemisia argentifolii Bellows & Perring, on cotton was documented dur ing 10-, 14-, or 24-h periods in tile Imperial Valley, California Hone ydew drops were collected on water-sensitive paper by placing 5th main stem node leaves inside open-ended plastic bags with strips of paper. Honeydew drops were also collected directly on open-ended plastic bag s placed on leaves, and honeydew sugars were analyzed using gradient a nion-exchange high performance liquid chromatography. No consistent di urnal patterns oi honeydew drop secretion emerged, but on I of the 4 d drop numbers were higher in tire morning (0500-1100 hours) than in th e afternoon and evening (1500-1900 hours), and drops were collected th roughout one 24-h period. On 3 of the 4 d, higher quantities of honeyd ew sugars were collected in the morning (0500 hours) than in the eveni ng (1500-1900 hours). Quantities and percentages of honeydew sugars ra nked as follows: trehalulose > melezitose > sucrose > fructose > gluco se. This ranking, with minor exceptions, did not change during the day (0500-1900 hours). Trehalulose accounted for approximate to 30% of th e total sugar mass in the honeydew. Honeydew sugar secretion and compo sition did not show a clear or consistent relationship with either lea f water potentials or temperatures.