379 



Thus, ws seem to have an aestival diapause weevil (responding to host) and a 

 hibernal diapausing weevil (responding to photoperiod) . 



741. , and Carter, F. L. 1978. Complexity of diapause in the boll weevil, 

 Anthonomus grandis Boheman. Proc. Entomol. Conf. Cronobiology, 12th. 

 Cronobiology Suppl., pp. 621-626. 



Studies in Arkansas showed that boll weevil diapause was affected by changes 

 in fruiting activity of the cotton plant. Generally, when larval develop- 

 ment occurred while fruiting levels were increasing or being held at a high 

 level, diapause in resulting adults was low (0-20%) . Diapause ranged from 

 20-50% when larval development coincided with decreasing fruiting levels, 

 and was at least 50% as the crop approached maturity. These data show that 

 the boll weevil not only responds to short photoperio^.s, that are characteristic 

 during ths fall ir. he temperate zones, but it may also respond to changes 

 in fruiting activity through the season. These studies also suggeste-i that 

 the boll weevil may utilize a chemical messenger, abscisic acid, in the plant 

 as an indicator of seasonal conditions. When 0.01 ppra of ABA was added to 

 synthetic medium in the laboratory, it had a significant effect on diapause 

 response and fecundity of the boll weevil. 



742. Pieters, E. P. 1976. Chemical control of overvintering boll weevils in 

 the Coastal Bend area of Texas. Tex. Agric. Exp. Stn. Prog. Rep. 

 PR-3419, 1 p. 



Two insecticide treatments aimed at reducing overwintering boll weevil popula- 

 tions were applied to five fields during 1975. Damaging boll weevil population 

 levels developed in the untreated check in only two of the five fields. In a 

 field where boll weevil populations did develop and where no additional insecti- 

 cides were applied to control fleahoppers, the treated plot had significantly 

 fewer boll weevils damaged squares and fewer fleahoppers. The number of 



