Water Balance, Host Utilisation, And Mass Rearing Improvements Of The Cockroach Oothecal Parasitoids, Aprostocetus Hagenowii (Hymenoptera: Eulophidae) And Evania Appendigaster (Hymenoptera: Evaniidae)
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Date
2016-04
Authors
Tee, Hui Siang
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Abstract
This thesis focuses on the water balance, host utilization and mass rearing
improvements of Aprostocetus hagenowii (Ratzeburg) (Hymenoptera: Eulophidae)
and Evania appeindgaster (Linnaeus) (Hymenoptera: Evaniidae), two ootheca
parasitoids of the American cockroach, Periplaneta americana (Linnaeus) (Blattidae:
Dictyoptera). Evania appendigaster had higher cuticular permeability than A.
hagenowii. All of the parasitoids, except A. hagenowii males, had similar percentage
total body water loss rate. The survival times of all the parasitoids, except E.
appendigaster males, reduced with decreasing relative humidity (RH) but this
phenomenon did not occur among sugar-fed parasitoids. In chambers with a 44 87%
RH gradient, both sexes of E. appendigaster preferred the wettest chamber. For A.
hagenowii, females preferred both the driest and the wettest chambers and males
preferred the driest ones. The effect of ootheca age and constant temperature on the
life history of A. hagenowii were studied. A. hagenowii could successfully develop in
oothecae attaining up to 72.9% of the total embryonic development time without any
effect on their fitness traits. The lower, upper and optimal temperature thresholds were
9.5, 34.2 and 31.1 °C, respectively. Temperature did not affect females’ reproductive
traits but did influence parasitism activities over time. The effect of ootheca age on
ootheca cannibalism in P. americana and its influence on ootheca age selection and
fitness in E. appendigaster was examined. Periplaneta americana differentially
cannibalized 1 d versus 10 40 d old oothecae. However, parasitoid females preferred
to parasitize 1 d old than 10 40 d old oothecae. The emergence rate was greater and
the handling time was shorter on 1 d old compared to older oothecae. For parasitoid
progeny, development time increased and body size and longevity decreased with
ootheca age. These results suggest that E. appendigaster females traded progeny
survival for fitness gains for themselves and their progeny. The minimum time of
heating required to kill oothecae was determined and their suitability as hosts after
different storage conditions (live, heat killed, and stored for 0.5 4 months at 4 °C) for
rearing parasitoids A. hagenowii and E. appendigaster was investigated. Heating at 48
°C for 45 min killed oothecae of all ages. Heat treatment improved the suitability of 4-
week-old oothecae as hosts for parasitoid rearing. For A. hagenowii, reduced
emergence rates were documented among cold-stored 3 4-week-old oothecae. The
number of progeny produced in 1–2-week-old and 3–4-week-old oothecae decreased
after cold-stored for 3–4 and 0.5–4 months, respectively. Evania appendigaster had
low emergence rates in cold-stored oothecae.
Description
Keywords
The water balance, host utilization and mass rearing improvements of Aprostocetus hagenowii , and Evania appeindgaster two ootheca parasitoids of the American cockroach