40 N. Veena and D. Manjunath
economical. With regard to parasitoids as biocon-
trol agents, they assume immense importance as
they account for 87 % suppression of pest insects
in nature in comparison to 12 % by predators and
1 % by pathogens (van Lenteren 1983 ). To realize
their effectiveness as potent biocontrol agents,
they need to be released in the field subsequent to
their mass production in the insectary employing
appropriate protocol. Further, the mass-produced
parasitoid individuals, especially females are re-
quired to possess superior fitness characteristics
in order to accomplish the desired goal in the
field. In addition, it would be ideal if the popu-
lation of the mass-produced parasitoid adults is
female-biased. It is a well established fact that
fitness traits as well as sex ratio of parasitoids
are influenced by various host, parasitoid, and
environmental factors. Fitness is often correlated
with adult size and it correlated with enhanced
longevity, temperature tolerance, effective host
searching ability, and greater reproductive poten-
tial (Ji et al. 2004 ; Aruna 2007 ; Gangadhar 2009 ).
The factors that contribute to parasitoid fitness
include host age and size, parasitoid age and size,
temperature, mating, and adult diet.
Parasitoid age influenced developmental
characteristics. In Trichogramma chilonis and
Trichogramma astriniae, female progenies were
the highest on the first day of adult life (Hi-
rashima et al. 1990 ). Progeny production and
fecundity were higher in young parasitoid fe-
males than in older ones (Guang and Oloo 1990 ).
The sex ratio of older females was male-biased
and young ones were female-biased in Tricho-
gramma minutum (Leatemia et al. 1995 ). Ovi-
position rate decreased with the parasitoid age
in Anagyrus pseudococci Girault (Avidov et al.
1967 ), Apoanagyrus lopezi De Santis (Odebiyi
and Bokonon-Ganta 1986 ), Tetrastichus incer-
tus Ratzeburg (Pitcoirn and Gutierrez 1992 ), and
Catolaccus grandis (Morales-Ramos and Cates
1992 ). In Ceratogramma etiennei Delvare, the
percent parasitization increased in young females
while it decreased with female age (Amalin
et al. 2005 ). In Ascogaster reticulatus Watanabe
(Honda 1998 ) and Chelonus sp. nr. curvimacula-
tus (Hentz 1998 ) young parasitoid females were
more fecund than older ones.
Parasitoid size is known to influence fecun-
dity with large females consistently laying more
eggs than small females. In some species, they
produce more eggs of larger size (Speight 1994 ).
Reproduction rate of large females remains high-
er and can be twice as high as small females re-
gardless of the size of the males they mate with
(Ji et al. 2004 ). Size fitness relationship of a
parasitoid has been demonstrated in Aphaereta
minuta (Nees) by Visser ( 1994 ) and Achrys-
ocaroides zwoelferi by West et al. ( 1996 ) who
observed that large females were more fecund
with larger eggs, high longevity, and greater host
searching efficiency than smaller ones. Simi-
lar results were obtained with Ascobara tabida
(Ellers et al. ( 1998 ). Further, it was also ob-
served that the fitness of the parasitoid increased
linearly with size. Sagarra et al. ( 2001 ) reported
that, Anagyrus kamali, large females have higher
longevity, higher reproductive longevity, higher
fecundity, higher oviposition rate, and a large
number of progenies.
Trichopria sp. is a 1.5–2 mm long, gregari-
ous parasitoid wasp of Exorista bombycis. Being
an endo-larval parasitoid of Bombyx mori, E.
bombycis is a serious problem while raising silk-
worm for cocoon production causing 10–20 %
mortality of larvae. Unlike the other parasitoids
of E. bombycis, Trichopria sp. is observed to
prevail and parasitize the puparia of E. bombycis
throughout the year in most cocoon markets lo-
cated in traditional districts of Karnataka, there-
by indicating its potential as an agent of biologi-
cal suppression of E. bombycis. It is proposed to
exploit Trichopria sp. as a biocontrol agent of E.
bombycis alongside Nesolynx thymus, which is
currently the recommended biocontrol agent of
this pest.Material and Methods
Host Culture
The puparia were obtained after allowing the post-
parasitic maggots collected from silkworm ( B.
mori) cocoon markets to pupate in the laboratory
(23–28 °C and 60–80 % RH) of the Department