THE INFLUENCE OF ENVIRONMENTAL-QUALITY ON SEXUAL SELECTION IN NAUPHOETA-CINEREA (DICTYOPTERA, BLABERIDAE)

We examined the impact of environmental conditions on the sex pheromon e and mating behavior of the cockroach, Nauphoeta cinerea. Previous re search on this species has shown that female behavior during courtship reflects female mate choice, male behavior correlates with male socia l status, and the male sex pheromone is the character used by females to assess males. In the present study, males and females were allowed to develop from adult emergence to sexual maturity in either a high- o r low-quality environment. The environment affected the quantities of sex pheromone components. We found significantly less 3-hydroxy-2-buta none and 4-ethyl-2-methoxyphenol, but not 2-methylthiazolidine, in the pheromone glands of males from a poor environment. Pheromone quality was also affected; the ratios involving 2-methylthiazolidine were alte red, while the ratio 3-hydroxy-2-butanone to 4-ethyl-2-methoxyphenol d id not change. Development to sexual maturity under these environmenta l conditions also influenced male and female sexual behavior. Male cou rtship activity reflected environmental influences; males from the low -quality environment took longer to initiate courtship and spent more time copulating with females from all environments. Male quality, as a ssessed by females, was also affected by their environment. Females we re slower to respond to the courtship of males from the poor environme nt, regardless of the females' own rearing environments. However, fema les from the low-quality environment also took longer to respond to th e courtship, and required more courtship, regardless of the males' rea ring environments. Thus, poor environments also increase female choosi ness. However there was only one significant interaction term, suggest ing that the environmental effects are general and that females do not show adaptive plasticity in mate choice. Studies of sexual selection that consider the effects of variable environments on behavior as well as the sexually selected morphology in other systems are likely to pr ovide new insights into this evolutionary process.