FEMALE CHOICE AND THE ADAPTIVE SIGNIFICANCE 
OF PROLONGED COPULATION IN NEZARA VIRIDULA 
(HEMIPTERA: PENTATOMIDAE)* 
By D. Kelly McLain 
Department of Biology, Emory University 
Atlanta, Georgia 30322 
Introduction 
High variance in male reproductive success characterizes male 
reproductive effort (Bateman, 1948; Trivers, 1972; Wade and 
Arnold, 1980). This results in strong selection pressures favoring 
male characteristics which enhance attractiveness or access to 
females (McCauley and Wade, 1978; Mason, 1980). Selection may 
also favor mechanisms in males to protect their sperm from 
displacement by other males from the sperm storage organs of 
females (Parker, 1970; Waage, 1979a; Ehrlich and Ehrlich, 1978; 
Zorn and Carlson, 1978). In some species, males guard females from 
reinsemination (Parker and Smith, 1975; Alcock, 1976, Waage, 
1979b). Some species employ prolonged copulation as a means of 
guarding females (Van Gerwen, et al, 1972; Alcock, 1980). 
However, behavior or morphology which appears adaptive in the 
context of ejaculate competition may have evolved in other contexts 
(Thornhill, 1980a). Thus, this report analyzes prolonged copulation 
in the southern green stink bug, Nezara viridula L., in terms of its 
value in sperm competition and non-reproductive functions. La¬ 
boratory studies attempt to determine if social factors mediate the 
duration of copulation and if the duration of copulation affects the 
fertilization success of males mating multiply-inseminated females. 
Field studies are employed to assess the role of prolonged copula¬ 
tion in reducing the level of parasitoidization of males by the 
tachinid fly, Trichopoda pennipes (F.) at the expense of the female. 
Laboratory and field data suggest that female N. viridula and 
parasitoids are more frequently attracted to large males. The 
significance of this preference to N. viridula females is also 
investigated. 
Copulation duration in N. viridula is highly variable, ranging 
*Manuscript received by the editor April 15, 1981 
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