Impact of Adult Size and Sib, Conspecific, and Random Mating in Trichopria ... 51
while undertaking mass production of the para-
sitoid under a biocontrol program. Therefore,
considering the importance of female population
in the suppression of host (pest) population in
bio-control programs, the superiority of random
mating among the progenies of several mothers
requires special mention.
There is a dearth of information as to the role
of mating among the progenies produced by a
single mother (sib) and those produced by a few
(conspecific) as well as several mothers (random).
Fisher ( 1930 ) reported that the parasitoids that re-
sort to random mating (panmictic) invest equally
in sons and daughters as against Hamilton ( 1967 )
who noted that parasitoids in the nature produce
female-biased population when their progenies
were allocated in host populations when avail-
able in patches. Based on his in-depth studies, he
proposed a model that explains that all the paren-
tal females are equally fecund, the females of the
offspring of these females are inseminated before
their dispersal due to random mating, and mat-
ing groups are limited to the offspring emerging
from the host patch parasitized by the parental
females. In the present investigation, the fact that
the random-mated females of Trichopria sp. have
invested more in daughters compared to sons is
in consonance with the hypothesis propounded
by Hamilton ( 1967 ).
When big and small males as well as big and
small females were confined together, it was
observed that big males mated with big females
invariably. In some replications, it was observed
that when small males mounted on big females,
the big males disturbed the mating pair and suc-
ceeded in warding off the small male mating with
the big female. In the treatment where small fe-
males were confined with big and small males,
the small males were found to mate with big fe-
males although in some replications big males
also mated with small females. It can, therefore,
be understood that big females prefer to mate
with big males and small females accept both big
and small males. Although in both treatments, the
rate of parasitism remained identical, progeny
production, including the females, was signifi-
cantly higher in the treatment involving mating of
big females with big males as against the mating
between small females and small males. The total
progeny production and female progenies from
the mating combination of small females and
small males though have declined considerably,
the sex ratio remained at par with mating be-
tween big females and big males as increase in
female production in the former and decrease in
female number in the latter relative to male num-
ber has remained identical. However, keeping in
view the importance of female numbers in the
population of a mass-produced parasitoid, any
mating combination resulting in the enhancement
of female production is desirable. Nonetheless, in
the study, we have realized such a performance in
the mating combination consisting of big females
and big males of Trichopria sp.
Ji et al. ( 2004 ) observed that in Anisoptera-
malcus calandrae parasitoid did not show distinct
preference for mating with males of specific size.
The reproduction rate of larger females in this
parasitoid remained higher than smaller ones and
could be twice as high as smaller females. Shi-
mamoto et al. ( 2006 ) working on Colletes per-
forator found that bigger males mate more often
than smaller males. Influence of male body size
related mate choice has been reported in Mega-
lothynnus klugii and Macrothynnus sp. (Alcock
and Gwynne 1987 ) with larger males more likely
to get mates. Our findings with Trichopria sp.
are in conformity with those of Shimamoto et al.
( 2006 ) and Alcock and Gwynne ( 1987 ).Acknowledgments The help rendered by way of
extending research facilities to the senior author during
the course of the Ph.D. program, Department of Studies
in Sericulture Science, University of Mysore is gratefully
acknowledged.References
Alcock J, Gwynne DT (1987) Courtship feeding and mate
choice in thynnine wasps (Hymenoptera: Tiphiidae).
Aust J Zool 35:39–47
Anonymous (1999) Natural enemies of Uzifly. Annual
Report, Central Sericultural Research and Training
Institute, Mysore, p 28