1980] 
McLain — Nezara viridula 
333 
fitness by reducing the level of displacement of sperm upon 
reinsemination of the female. The duration of the second copulation 
does not influence the degree of sperm displacement. Thus selection 
may favor longer duration of copulation when males are mating 
virgins. In fact, when females are mated twice the 1st mating is 
almost invariably the longer (McLain, 1981). Once-mated females 
are more likely to oviposit before remating if the first mating is of 
long duration (McLain, 1981). This could also select for long 
copulation durations since the 1st egg mass is then laid free from 
sperm competition. 
The duration of copulation is influenced by the social environ¬ 
ment. The mating pairs isolated from jars with the greater number 
of males mated for much longer duration. A similar result was 
obtained previously by utilizing jars with 9 males and 1 female or 9 
females and 1 male (McLain, 1981). However, in the previous 
experiment the mating pair was not isolated. Since the result did not 
change with this additional manipulation, the duration of copula¬ 
tion appears in part mediated by the social environment perceived at 
the initiation of mating as a means of guarding females from other 
males. 
Males may prefer copulations of longer duration to reduce the 
level of parasitoid infestation they receive at the expense of the 
female while they contine to broadcast their presence to other 
females. If the tachinid parasitoid is attracted to an emitting male 
which is mating, there is a high probability that she will oviposit on 
the female. 
Parasitoidization reduces the fitness of stink bugs because they 
die when the parasitoid larvae pupate within them. Parasitoidiza¬ 
tion is also an energetic drain which greatly reduces the energy an 
adult can allocate to reproductive effort (Shahjahan, 1968). 
The genetic interests of the male are better served by parasitoidi¬ 
zation of the female rather than additional parasitoidization of 
himself. The female will probably remate and cease to use the males 
sperm in later oviposition. Therefore, any future reproductive 
success the male is afforded must result from his ability to compete 
for and inseminate other females, an ability which would be greatly 
compromised by high levels of parasitoidization. 
Size may be an important determinant of male fitness (McCauley 
and Wade, 1978; Thornhill, 1980a). In both the field and the 
