48 N. Veena and D. Manjunath
populations while rendering the pest manage-
ment program eco-friendly, long lasting, and
cost effective. In biological control program,
hymenopteran parasitoids are often mass pro-
duced before they are released to field. During
mass multiplication, emphasis is laid on the pro-
duction of high-quality parasitoid with female-
biased population. The quality of mass-produced
parasitoids are often influenced by the host, para-
sitoid, and environmental factors. Therefore, it is
important to identify the factors and their influ-
ence on the production of quality females. These
factors include host age and size, host density,
host quality, parasitoid age, size and density, mat-
ing, adult diet, and temperature, etc.
Literature pertaining to factors influencing
parasitoid quality and sex ratio is rather scanty.
In nature, most hymenopteran parasitoids repro-
duce by arrhenotokous parthenogenesis, which is
the dominant mode of sex determination, where
an unfertilized egg develops into a male and a
fertilized one into a female (Heimpel and de Boer
2008 ). For a female, finding a mate is only the
first step towards production of an optimal sex
ratio throughout her life. Finding a mate does not
always guarantee that the female will produce
progenies with optimal sex ratio. The quality
of male and his sperms impact the production
of daughters at an optimal rate (Boivin 2013 ).
Sib mating is commonly found among gregari-
ous parasitoids that might select multiple mating
ways thus diversifying their progenies through
multiple males (Ridley 1993 ).
Trichopria sp. is one among the 20 hymenopter-
an parasitoids that have been identified to parasit-
ize Tachinid (uzi) fly, Exorista bombycis. Being
an endo-larval parasitoid of mulberry silkworm,
Bombyx mori, E. bombycis has been known to
inflict 10–20 % reduction in cocoon yield in
the premier silk-producing states of India since
- Unlike other parasitoids of E. bombycis,
Trichopria sp. assumes considerable importance
because the parasitoid prevails and parasitizes
the puparia of E. bombycis throughout the year
in the cocoon markets located in the traditional
districts of Karnataka, thereby underlining its po-
tential as an agent of biological suppression of E.
bombycis. The present investigation is undertaken
to generate information about how adult size and
mating condition (sib, conspecific, and random)
influenced progeny production and sex ratio in
Trichopria sp., an idiobiontic pupal parasitoid of a
number of lepidopteran and a few dipteran pests.
The information thus generated would be of help
in understanding a few mechanisms among many
others involved in enhancing the efficiency of the
mass production unit of the parasitoid.Material and Methods
Culture of the Host
The hosts, E. bombycis puparia, were obtained
after allowing the post-parasitic maggots, col-
lected from the government cocoon markets at
Ramanagaram/Kollegal (Karnataka), to pupate
in the laboratory (23–28 °C and 60–80 % RH) of
the Department of Studies (DOS) in Sericulture
Science, University of Mysore.Culture of the Parasitoid
The stock cultures of the parasitoid, Trichopria
sp., cultured in the pupae of E. bombycis, were
procured from the Central Sericultural Research
and Training Institute (CSRTI) and maintained
at 23–28 °C and 60–80 % RH with feeding 30 %
honey.
Two-day-old virgin females and unmated
males of the parasitoid were used for study.
The effect of the adult male and female size of
Trichopria sp. on mating efficiency and repro-
ductive performance was determined by allow-
ing 2 day-old virgin females and unmated males
to mate and offering them 3 day-old puparia of
E. bombycis for oviposition at 1:4. The follow-
ing mating combinations were used to record the
reproductive performance.Influence of Parasitoid Size
Mating combinations were: (i) B♀ × B♂, (ii)
B♀ × S♂, (iii) S♀ × B♂, and (iv) S♀ × S♂.