MEETING ABSTRACTS OF PAPERS PRESENTED AT THE 6TH MEETING ON WHITEFLIES IN FIELD CROPS AND VEGETABLES February 26, 1987 Gilat Experiment Station, ARO, Gilat, Israel A: BEMISIA TABACI INFESTATIONS: ONSET, POPULATIONS, DAMAGE AND BEHAVIOR WHITEFLY POPULATIONS IN VEGETABLES IN 1986 .C. SHOHAM Div. of Plant Protection, Extension Service, Ministry o f Agriculture, Tel Aviv, Israel As in previous years, the following estimate of Bemisia tabaci populations in vegetables during the summer of 1986 was derived from weekly routine reports of Extension Plant Protection Advisors stationed at diverse District Extension Offices throughout Israel. Due to the lack of regular pest scouting in vegetable crops, these reports are not based on exact population counts or damage assessments, but represent observations made during routine field inspections, on the onset of whitefly activity in the spring and the subsequent rate of population increase and damage to various vegetable crops. The first activity of whiteflies was noted on March 13, 1986, in eggplants in the Jordan Valley; this was 2 weeks later than in 1985, but still 5 to 6 weeks earlier than in the years 1980- 1984. Three weeks later, on April 3, whitefly activity was found already in most vegetable crops in this area as well as in fields of canning tomatoes in the Nazareth area, and on April 10 in the western part of the Yizre'el Valley, in Lakhish, and in the coastal plain near Ashdod. It should be noted that these are the earliest reports of whitefly activity from areas outside the Jordan Valley (10 to 20 days earlier), since the onset of our whitefly survey in 1980. Due to the absence of adverse climatic conditions (Le., dry spells), whitefly populations increased rapidly throughout May and until the third week of June, when severe damage was already noted in some localized areas, especially in tomatoes and cucurbits. During July and the first 2 weeks of August, infestation levels remained more or less con- stant, but increased rapidly toward the end of August, when extremely high populations caused severe damage to most vegetable crops, and especially tomatoes, eggplants, peppers and cucurbits. In spite of massive" and frequent pesticide applications, pest populations increased further at an accelerated pace throughout September, causing extreme damage to sensitive vegetable crops, not infrequently to the point of total destruction. Phytoparasitica 15:3, 1987 259