10 



MISC. PUB. 1178, U.S. DEPT. OF AGRICULTURE 



press a population with just two generations per 

 year to the same extent as a population with 

 four generations per year, we would have to 



release three to 10 times as many insects per 

 release as are required to suppress a population 

 with four generations per year. 



Discussion 



The preceding calculations indicate that con- 

 ditional lethal traits could be very effective in 

 suppressing insect populations. The greatest 

 advantage of using adaptations to climate or 

 seasonal changes as conditional lethal traits is 

 that these traits already exist in populations at 

 latitudes or altitudes different from those of the 

 locality where we desire complete suppression. 



To assess the possibility of utilizing these 

 adaptations to suppress an insect population, 

 one would collect a strain from a locality with 

 a distinctly different season, select the strain to 

 apparent homozygosity for one or more traits, 

 cross the latter to the strain from the locality 



designated for suppression, and determine the 

 expression of the traits in hybrid generations. 

 Since temperature may modify responses to 

 photoperiod (2), the expression of the traits in 

 hybrid generations should be checked in an en- 

 vironmental chamber programed to simulate 

 conditions in the field. In this way one could 

 detect undesirable genotypes in the release 

 strain. Although desirable, one need not deter- 

 mine precisely the inheritance of each trait. The 

 investment required to assess the feasibility of 

 this proposed suppression method in any par- 

 ticular instance would not be prohibitive. 



(3) 



Literature Cited 



(1) Commonwealth Institute of Entomology. 



1951-69. distribution maps of insect pests. 

 Series A 41, 228 pp. London. 



(2) Danilevskii, A. S. 



1965. PHOTOPERIODISM AND SEASONAL DEVELOP- 

 MENT of insects. 283 pp. London. 



(6) Masaki, S. 



1961. GEOGRAPHIC VARIATION OF DIAPAUSE IN 



insects. Hirosaki Univ. Facul. Agr. Bui. 

 7: 245-251. 



(7) 



ed. 



1968. PHOTOPERIODIC ADAPTATIONS TO INSECTS 

 AND acari. 269 pp. Leningrad Univer- 

 sity. 



(4) Hogan, T. W. 



1966. PHYSIOLOGICAL DIFFERENCES BETWEEN 

 RACES OF TELEOGRYLLUS COMMODUS 

 (WALKER) (ORTHOPTERA: GRYLLIDAE) RE- 

 LATED TO A PROPOSED GENETIC APPROACH 



to control. Austral. Jour. Zool. 14: 

 245-251. 



(5) Klassen, W., Knipling, E. F., and McGuire, J. U. 



1970. the potential for insect population 

 suppression by dominant conditional 

 lethal traits. Ent. Soc. Amer. Ann. 

 63: 238-255. 



1968. geographic adaptation in the seasonal 

 life cycle of mamestra brassicae 

 (linne) (lepidoptera: noctuidae). Hi- 

 rosaki Univ. Facul. Agr. Bui. 14: 16-26. 



(8) North, D. T., and Holt, G. 



1968. INHERITED STERILITY IN PROGENY OF IR- 

 RADIATED male cabbage loopers. Jour. 

 Econ. Ent. 61: 928-931. 



(9) Proverbs, M. D., and Newton, J. R. 



1962. some effects of gamma radiation on 

 the reproductive potential of the cod- 

 ling moth carpocapsa pomonella (l.) 

 (lepidoptera: olethruetidae). Canad. 

 Ent. 94: 1162-1170. 

 (10) Walker, D. W., and Pedersen, K. B. 



1969. population models for suppression of 

 the sugarcane borer by inherited par- 

 TIAL sterility. Ent. Soc. Amer. Ann. 

 62: 21-26. 



Appendix 



The following method is used to calculate the flooded with a partially sterile release strain 

 genotypic frequencies in hybrid generations (aabb) in the parental, Fi, F 2 , and F 3 genera- 

 when a native population (AABB) is over- tions. 



