Trap catches of the sweetpotato whitefly （Homoptera： Aleyrodidae） in the Imperial Valley, California, from 1996 to 2002

An outbreak of the sweetpotato whitefly, Bemisia tabaci （Gennadius）, biotype B occurred in the Imperial Valley, California in 1991. The insects destroyed melon crops and seriously damaged other vegetables, ornamentals and row crops. As a result of the need for sampling technology, we developed a whitefly trap （named the CC trap） that could be left in the field for extended time periods. We used the traps to monitor populations ofB. tabaci adults during year-round samplings from 1996 to 2002 to study variations in the weekly trap catches of the insect. The greatest number ofB. tabaci adults was recorded in 1996, followed by a continuing annual decrease in trap catches each year through 2002. The overall decline of B. tabaci is attributed in part to the adoption of an integrated pest management （IPM） program initiated in 1992 and reduced melon hectares from 1996 to 2002. Other factors may also have contributed to the population reductions. Seasonally, B. tabaci trap catches decreased during the late summer and fall concurrent with decreasing minimum tempera- tares that are suggested to be a significant factor affecting seasonal activity and reproduction.     

Pink bollworm moth （Lepidoptera： Gelechiidae） catches in the Imperial Valley, California from 1989 to 2003

We examined the patterns of male pink bollworm （PBW）, Pectinophora gossypiella （Saunders）, moth catches in gossyplure-baited traps over a 15-year period from 1989 to 2003 in the Imperial Valley, California, USA. Monitoring was conducted during periods when different pink bollworm areawide control strategies were being used. Numbers of male pink bollworm moths caught in gossyplure-baited traps progressively decreased each year from 1990 to 1994 during short-season cotton production. High numbers of male moths caught in traps from 1995 to 1997 may have been related to moth migrations from the large cotton acreages grown in the Mexicali Valley bordering the Imperial Valley. Transgenic Bollgard （Bt） cotton was planted in 3% of the cotton area in 1996 and thereafter in 80%- 94% of the cotton area from 1997 to 2003. Pink bollworm moth trap catches were significantly lower from 1998 to 2003 than catches in 1995 to 1997, except for 1999. The trapping results suggested that Bt cotton had significant input on reduction of pink bollworm populations, confirming results of other investigators and providing additional documentation on the benefits of the Bt cotton culture.