Sex Ratios, Development, and Parasitization Behavior of the Parasitoids Cotesia rubecula and Cotesia glomera/a (Hymenoptera: Braconidae)
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Authors
Powers, Elizabeth C.
Issue Date
1998
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Cotesia rubecula and Cotesia glomerata are braconid parasitoids. Females of
both of these wasps oviposit in first or second instar Pieris rapae larvae, and the wasp
larvae develop and feed on the host internally. C. rubecula is solitary and females
oviposit one to two eggs in a host. C. glomerata is gregarious, with females ovipositing
16-52 eggs. Roughly seven to ten days after oviposition, late instar Cotesia larvae
emerge from the host caterpillar, spin cocoons and continue development, emerging as
adults five to ten days later.
Most Hymenoptera have a haplodiploid genetic system. Unfertilized eggs
develop as haploid males and fertilized eggs develop as diploid females. Gregarious
species such as C. glomerata typically have a high frequency of inbreeding. Matings
between genetically similar individuals may occur, resulting in production of diploid
males. These males are either unable to develop properly or are sterile. In species with a
single gene locus for sex determination successive inbreeding would produce many
diploid males. The use of multiple loci for sex determination may have evolved in
species which habitually inbreed, circumventing this diploid male problem. Due to
mortality among Cotesia wasps and high frequency of all-male broods, insufficient data
were collected to draw conclusions about sex determination in these parasitoids.
C. rubecula and C. glomerata were found to have similar timeframes for
development from oviposition to adulthood, but differed in the amount of time spent as
larvae and pupae. At the field site, 26.1 % of P. rapae collected had been parasitized by
C. rubecula, 29.1 % died in the laboratory and may have been parasitized, while 44.9% of
P. rapae larvae pupated normally.
Description
v, 26 p.
Citation
Publisher
Kalamazoo College
License
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