Tex., and from assorted stocks maintained at 

 Fayetteville, Ark. Evaluations initially were 

 for tolerance and preference forms of resist- 

 ance. Significant advances were made with 

 red plant color, increased pubescence, rapid 

 fruit set, and Frego bract characters, but sup- 

 plemental controls still were needed for com- 

 petitive levels of yield. Four years of selection 

 for antibiosis revealed that little genetic 

 advance was possible, largely because the non- 

 genetic sources of variation were proportion- 

 ately large. Cottons of Hopi and Yugoslav 

 origin, however, did show some promise. 



77. Jenkins, J. N., Lafever, H. N., and 

 Maxwell, F. G. Boll weevil resistance factors 

 in cotton. Agron. Abs. 1964: 69. 1964. 



The regional collection of upland cottons 

 contains approximately 800 entries. In general, 

 all lines are susceptible to the boll weevil. Sev- 

 eral hundred of these lines have been assayed 

 for components that contribute to boll weevil 

 resistance. Antibiosis for adult weight and 

 rate of boll weevil oviposition on the cotton 

 line were selected as the resistance components 

 to be measured. An antibiosis technique was 

 developed and used to assay 356 cotton lines. 

 Forty lines were selected that reduced weevil 

 size by more than 10 percent. A technique was 

 developed to measure the rate of boll weevil 

 oviposition on cotton lines. Three hundred 

 seventy-five lines were assayed in nonreplicated 

 tests. Replicated tests were conducted on selec- 

 tions from the nonreplicated screen, selections 

 from the antibiosis screen, and on certain Fi 

 crosses between oviposition screen selections. 

 Testing of the Fi's has not been completed. In 

 replicated tests, weevils on 15 cotton lines had 

 an egg production ratio (x of test line/x of 

 commercial check) of less than 0.8. Three of 

 these 15 were selections from the antibiosis 

 screen and are thus selected lines in two cate- 

 gories of boll weevil resistance. 



78. Jenkin, J. N., and Maxwell, F. G. 

 Chemotrophic responses of the boll weevil to 

 cotton extracts I— II. 15th Ann. Cotton Impr. 

 Conf. Proc, pp. 64-75. 1963. 



Various methods of searching for boll weevil 

 resistance mechanism in cotton are discussed. 

 The biologically active compounds found in 

 cotton are discussed. These are an arrestant 

 and feeding stimulant, an attractant, and a re- 

 pellent. Data are presented that show some 

 cottons contain antibiosis to the boll weevil. 

 The possibilities of utilizing the antibiosis ap- 

 proach as well as building resistance through 

 a combining of the biologically active com- 

 pounds in the correct proportions are dis- 

 cussed. 



79. Jenkins, J. N., Maxwell, F. G., and 

 Buford, W. T. Differential rates of egg lay- 

 ing by the boll weevil on several varieties of 

 cotton. 16th Ann. Cotton Impr. Conf. Proc, 

 pp. 56-65. 1964. 



12 



A laboratory test to determine the boll weevil 

 oviposition rate on cotton lines is described. 

 The method developed was utilized to screen a 

 large number of cotton lines. A few were 

 found that reduced oviposition 30 percent when 

 compared with a commercial variety. Theoret- 

 ical calculations are presented showing the 

 effect of such a resistance mechanism on popu- 

 lation dynamics. 



80. Jenkins, J. N., and others. Investiga- 

 tions of the water extracts of Gossypium, 

 Abelmoschus, Cucumis and Phaseolus for an ar- 

 restant and feeding stimulant for Anthonomus 

 grandis, Boh. Crop Sci. 3: 215-219. 1963. 



F. G. Maxwell, J. C. Keller, and W. L. Par- 

 rott, joint authors. 



Four Gossypium species, a two-species hy- 

 brid, a three-species hybrid, two genetic mu- 

 tants, two Upland varieties, and two Upland 

 strains were surveyed. A bioassay method, 

 with agar used as a substrate in the form of 

 cylindrical plugs wrapped in Whatman No. 1 

 filter paper, is described. From the data pre- 

 sented the following conclusions were drawn: 

 (1) The water extract of cotton plants con- 

 tained a substance (s) that acted as a powerful 

 arrestant and feeding stimulant to the boll 

 weevil. (2) The boll weevils exhibited prefer- 

 ence differences for the water extracts from 

 various genetically different Gossypium lines 

 and species. The same preference order was 

 shown for whole fresh squares. (3) The Asiatic 

 species G. herbaceum and G. arboreum were 

 the least preferred of all Gossypium lines 

 tested. (4) Seedlings were shown to be usable 

 in a screening program for low concentrations 

 of arrestant and feeding stimulant. (5) Of the 

 four genera tested, the substances were found 

 in Gossypium only. (6) Beans and okra seed- 

 lings normally nonacceptable to the boll weevil 

 became acceptable for feeding after being 

 sprayed with the extract from Delfos squares. 



81. Jenkins, J. N., Maxwell, F. G., and 

 Parrott, W. L. A technique for measuring 

 certain aspects of antibiosis in cotton to the 

 boll weevil. Jour. Econ. Ent. 57: 679-681. 

 1964. 



The technique described utilizes lyophilized 

 cotton-square powder as the basic ingredient. 

 It makes possible the rapid evaluation of dif- 

 ferent lines of cotton for antibiosis. This tech- 

 nique was shown to be much less variable than 

 field measurements for the same properties. It 

 minimizes the morphological and nutritional 

 aspects of various square sizes as a factor in 

 antibiosis. By using the technique, antibiosis 

 was found to be present in Gossypium thurberi, 

 which resulted in smaller weevils and a longer 

 developmental period. The limitations of the 

 technique are discussed. The technique is be- 

 lieved to have application with other insects 

 and crop plants in host-plant resistance pro- 

 grams. 



