FIELD-EVALUATION OF 14 SOYBEAN GENOTYPES FOR RESISTANCE TO WHITEFLY (HOMOPTERA, ALEYRODIDAE) INFESTATIONS

Fourteen soybean genotypes in maturity groups VII and VIII were evalua ted for resistance to Bemisia argentifolii Bellows & Perring and Trial eurodes abutilonea (Haldeman) at 2 field locations in Tift County, Geo rgia, in 1993 and 1994. Significant differences in mean whitefly densi ties were observed among the 14 soybean genotypes. 'Perrin', 'Cook', a nd 'N88-91' had significantly lower mean numbers of whiteflies than ma ny of the other entries during both seasons at both test sites. Fewer B. argentifolii eggs were oviposited on these 3 soybean entries compar ed with the susceptible varieties 'Braxton' and 'Cobb', demonstrating an antixenosis plant resistance response. The soybean breeding lines ' N89-1' and 'F90-724' also were highly preferred hosts for B. argentifo lii oviposition. Much lower T. abuttlonea population densities were ob served; however, the same general trends in host preference were obser ved. More than 70% of the mean whitefly population was composed of B. argentifolii in 1993 and 95% was B. argentifolii in 1994. Sticky traps were used to monitor the presence of both species of adults in the fi eld and to determine when peak adult populations occurred. Trap captur es were low in June of both years and rose steadily until whitefly den sities peaked in mid-to late September.