475 



flubenzuron (N-(4-chlorophenyl)-N-'--(2,6-difluorobenzoyl) urea), fractionated 

 irradiation of pupae, and fractionated irradiation of adults plus diflu- 

 benzuron. 



938. ; Ll^>yd, E. P.; Lue, P. S.; and Wright, J. E. 1980. Boll weevils: 

 competitiveness uf sterile males in isolated field plots. J. Econ. 

 Entomol. 73: 213-217. 

 In Louisiana and in North Carolina, isolated 0.2 ha cotton plots were used to 

 evaluate the competitiveness of male Anthonomus grandis grandis Boheman steri- 

 lized by one of 3 treatment methods: fumigation for 90 min with bisazir (P, P- 

 bis(l-aziridinyl)-N-methylphosphinothiotic amide) at atmospheric pressure, 

 followed 30 min later by a 5 sec dip in a 1.35% solution of penfluron (2, 6- 



difluoro-N-( ( (4- (tr if luoromethyl) phenyl) amino) carbonyl)benzamide) in acetone; 



137 

 10,000 rad of gamma irradiation from a "^ Cs source while the weevils were 



anesthetized in N2, followed by a 5 sec dip in a 0.1% solution of dif lubenzuron 



(N-( ((4-chlorophenyl)amino)carbonyl)-2, 6-dif luorobenzamide) in acetone; and a 



total dose of 6750 rad administered in 25 fractions of 270 rad each in the pupal 



and early adult stages. Egg hatch in the plots into which the treated males and 



untreated males were released in a 120:40 ratio along with the 300 untreated 



virgin females was significantly lower than in plots into which only untreated 



weevils were released (<73 vs. 98%). Overall competitiveness of sterile males 



to untreated males was 23.0% for the fumigation treatment, 16.9% for the acute 



irradiation treatment, and 12.0% for the pupal fractionation treatment. There 



was no significant difference in competitiveness between the acute irradiation 



and fumigation treatment. Because of the safety and simplicity of the acute 



irradiation plus dif lubenzuron treatment, we proposed it for sterilizing boll 



weevils for the North Carolina-Virginia Boll Weevil Eradication Trial program. 



