24 



decreases, (b) the rate of development, measured by pupation time, decreases; 

 that is, developmental time Increases, (c) the weight of developing larvae, 

 and even pupal weight, Is decreased and (d) addition of amount of D2O greater 

 than 50% of the total water completely inhibits larval devclopnent; (3) levels 

 of heavy water above 35% in the larval diet result in the sterility of at 

 least 89Z of the insects reared on the diet, causing a decrease in egg pro- 

 duction, regardless of the sex treated, plus an increase In the time required 

 for maturity. If the use of D^O can be perfected, the laborious handling of 

 individual weevils in a sterile-release program might be eliminated. 



41. Beck, S. n., and Maxwell, F. G. 1976. Use of plant resistance. l£ 

 C. B. Huffaker and P. S. Messenger (eds.). Theory and Practice of 

 Biological Control, pp 615-636. Academic Press, New York. 

 Probably u:ore is currently known about biologically active materials in the 

 cotton plant that affect the behavior of the boll weevil than for any other 

 insect - host situation. A program was begun in 1962 at the USDA Boll Weevil 

 Research Laboratory at State College, Mississippi, to determine some of the 

 factors involved in the selection (host preference) of cotton and other alter- 

 nate hosts of the boll weevil. The following briefly describes progress made 

 by a number of researchers over the past 5*years. 



42. Beckham, C. M. 1970. Control of cotton insects with ultra-low-volume 



sprays. J. Ga. Entomol. Soc. 5: 78-82. 

 Field experiments were conducted in 1968 and 1969 to evaluate different in- 

 secticide formulations applied by ground equipment to cotton as ULV sprayr 

 for control of the boll weevil, Anthonomus grandis Boheman; bollwjrms, HeliothiB 

 spp.; and spider mites, Tetranychus spp. The insecticides tested were: toxa- 

 phene + methyl parathion; malathlon + methyl parathion; C-9491 (0-(2,5-dichlc 

 iodophenyl) 0,0-dimethyl phosphorothioate) ; BCS-506 (0-C2,5-dichloro-4-bromophenyl) 



Loro-'*- 



