ALLOTHROMBIUM-PULVINUM EWING (ACARI, TROMBIDIIDAE), AN IMPORTANT EARLY-SEASON NATURAL ENEMY OF APHIS-GOSSYPII GLOVER (HOM, APHIDIDAE) IN COTTON

Early-season populations of the cotton aphid Aphis gossypii, its ectop arasite Allothrombium pulvinum, and other natural enemies (such as spi ders, coccmellids, aphidiids and syrphids) were surveyed in 7 cotton f ields with different insecticide uses and cultural practices in Sheyan g County, Jiangsu, China in 1991. A. pulvinum was the most abundant na tural enemy of A. gossypii and accounted for an average of 80 % of nat ural enemies in cotton fields. The abundance of A, pulvinum was low in flooded fields and increased with the number of years since the field has been rotated from flooded to dried conditions. A. pulvinum was al so more abundant in monoculture cotton fields than in cotton-wheat int ercropping fields. A. pulvinum was a major limiting factor of A. gossy pii population growth early in the season when other natural enemies o f A. gossypii were rare. Other natural enemies such as spiders and coc cinellids increased in abundance later in the season and complemented A. pulvinum in providing successful control of early-season A, gossypi i in unsprayed cotton fields. The role of A, pulvinum in integrated co tton pest control is also discussed.