Station indicated that the spray offered little, 

 if any, control of the boll weevil. The loss re- 

 sulting from its use was about $100 per acre 

 greater than with recommended methods. 



132. Mitchell, E. R., and Mistric, W. J., Jr. 

 Concepts of population dynamics and estima- 

 tion of boll weevil populations. Jour. Econ. 

 Ent. 58: 757-763. 1965. 



Information on recovery, movement, and 

 mortality of the boll weevil was observed from 

 field-cage studies in North Carolina during 

 1962. The average recovery of weevils on cotton 

 plants was 65.5 percent, and 88.8 percent of the 

 recovered weevils were found on squares, flow- 

 ers, and bolls. Variation from the average re- 

 covery in excess of 10 percent occurred in about 

 one out of four examinations. This variation 

 appeared to be due to many factors acting to- 

 gether rather than to single factors such as 

 generation, age, sex, and the number of weevils 

 or date and time of day of examination. 

 However, plant maturity enhanced recovery. 

 Migration of first-generation weevils (mostly 

 females) was indicated on July 28 and 30, but 

 the tendency to escape did not persist. The 

 mortality rate of overwintered and second- 

 generation weevils was approximately 2 per- 

 cent per day, and that of first-generation wee- 

 vils was 1 percent. 



Formulae for the estimation of weevil popu- 

 lations are given. 



133. Mitchell, E. R., and Mistric, W. J., Jr. 

 Seasonal occurrence of diapause and hiberna- 

 tion of the boll weevil in North Carolina. Jour. 

 Econ. Ent. 58 : 309-312. 1965. 



Investigations were conducted in 1961 and 

 1962 in and near a cottonfield with high pro- 

 ductive level and effectively treated with in- 

 secticides for boll weevil control and a field 

 with low productive level and virtually un- 

 treated. With one exception, the initiation of 

 diapause in the field was closely associated with 

 the onset of maturity in the cotton plants. Dia- 

 pausing weevils began to hibernate in late 

 August near the untreated field and in late Sep- 

 tember near the treated field. A large number 

 of weevils hibernated rather abruptly during 

 late September near the untreated field. How- 

 ever, the number of weevils in hibernation near 

 the untreated field gradually declined during 

 October and November; which indicates that 

 many of the hibernating weevils apparently 

 died before the onset of winter. During the 

 same period, the number of hibernating wee- 

 vils steadily increased near the treated field. 



134. MlTLlN, N. The physiology and toxi- 

 cology of chemosterilants. 12th Internatl. 

 Cong. Ent. Proc. London. 1964: 511-513. 1965. 

 (Abstract) 



Several guanine analogs were tested as in- 

 hibitors of reproduction. Two, 8-bromoguanine 

 and 9 methyl, 2 butyl guanine were found to be 



effective ovarian growth inhibitors in the boll 

 weevil. 



135. Mitlin, N., Bartlett, A. C, and Kel- 

 ler, J. C. Elimination rate and effect on re- 

 production of ingested radiophosphorus in the 

 boll weevil. Jour. Econ. Ent. 58: 119-121. 

 1965. 



The biological half-life of ingested P 32 was 

 5.3 days in females and 7.3 days in males. Germ 

 cells were relatively resistant to effects of the 

 isotope. Ingested amounts up to 3.5//.C caused 

 only a small decrease in fecundity, and when 

 either the male or female was fed the isotope 

 no effects on progeny or genetic changes could 

 be detected. Sterile matings resulted only when 

 both sexes were fed the isotope. There was no 

 obvious chromosomal damage in the germ cells, 

 and no phenodeviants appeared in insects 

 reared to the third filial generation. By feeding 

 P 32 , sperm or seminal fluid or both could be 

 labeled and traced to the spermatheca and 

 ovaries of mated females. Larvae reared in a 

 radioactive medium were inhibited in their 

 development and only a small percentage de- 

 veloped to adulthood. 



136. Mitlin, N., and Vickers, D. H. Gua- 

 nine in the excreta of the boll weevil. Nature 

 [London] 203: 1403-1404. 1964. 



The purine guanine was identified in the ex- 

 creta of the boll weevil by paper chromatogra- 

 phy and spectrophotometry. It is hypothesized 

 that the appearance of this unusual purine may 

 be the result of the deficiency of the enzyme 

 guanase. 



137. Mitlin, N., Vickers, D. H., and Gast, 

 R. T. Estimation of nitrogenous compounds 

 in the feces of boll weevils, Anthonomus gran- 

 dis, fed different diets. Ent. Soc. Amer. Ann. 

 57: 757-759. 1964. 



The effects on the nitrogenous end products 

 of the metabolism of the boll weevil fed on arti- 

 ficial diet, cotton squares, or bolls were deter- 

 mined. Fecal analyses for amino nitrogen, 

 ammonia, creatine, creatinine, guanine, urea, 

 and uric acid showed that presence of these 

 materials varied with the type of diet fed the 

 insects. The purine guanine was found in rela- 

 tively large quantities in the feces of weevils 

 fed all three diets. A metabolic block in its 

 deamination was hypothesized. 



138. Mitlin, N., Vickers, D. H., and Hedin, 

 P. A. End products of metabolism in the boll 

 weevil, Anthonomus grandis Boheman: Non- 

 protein amino acids in the faeces. Jour. Insect 

 Physiol. 10: 393-397. 1964. 



As a part of a study of nitrogen metabolism, 

 the feces of the boll weevil were examined for 

 nonprotein amino acids. By use of chromato- 

 graphic techniques, 20 amino acids in an 

 ethanolic extract were detected and the quan- 

 tities estimated. By acid hydrolysis, 23 amino 

 acids were detected. The free and bound non- 



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