Mate Choice and Lepidopteran Mating Behavior

Abstract

Our understanding of the evolution and adaptive features of animal mating behavior has dramatically improved in recent years as our understanding of the process of sexual selection and its consequences have been refined. Darwin (1871) first proposed sexual selection as the evolutionary process that gave rise to bizarre and seemingly maladaptive traits such as the tail of the peacock and the brilliant colors of male butterflies. He reasoned that the negative effects of these traits on male survivorship were outweighed by their positive effects on male reproductive success during courtship with females and competition with other males for access to females. Ronald Fisher (1958) later-1930-pointed out that in order for this process to have begun in the first place there had to have been some reproductive advantage to those females who chose for mates, males with certain traits. He argued that those traits used by females in mate selection must be correlated with high quality genes possessed by the male or high quality paternal care or investments the male has to offer. More recently, Robert Trivers (1972) explained that females are generally expected to be more selective than males because they usually make a larger investment in each offspring than does the male, and therefore have more to lose by copulating with low quality mates. In other words, a female's reproductive success may be viewed as being limited more by her ability to acquire nutrients for the production and care of her offspring rather than by the number of matings she obtains. Such a limitation would, in turn, favor care in the selection of mates. Males, on the other hand, typically invest little other than sperm in each of their offspring. Therefore their reproductive success is limited primarily by the number of copulations they can obtain rather than the number of gametes they can produce. Males, then, are generally expected to search out females and to mate willingly with any receptive female. The mating behavior of the Lepidoptera generally conforms to these expectations. After eclosion, females attract males either visually (butterflies and some moths) or chemically (most moths). A male searching for females locates one by using these signals, flies towards her, and courts her by barraging her with visual, chemical, and tactile signals. The male's chemical signals are typically produced by specialized structures such as hairpencils or patches of specialized scales on the wings. Females are generally passive during courtship but, if receptive, those of some species assume postures that facilitate the act of coupling. Copulation lasts from less than one to more than several hours after which the male departs and renews his search for mates. The female, on the other hand, (after copulation) ceases to emit sex attractants and becomes refractory to mating attempts by males. Her behavior becomes concentrated on efforts to locate oviposition sites and