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Title: Rearing temperature and parasitoid load determine host and parasitoid performance in Manduca sexta and Cotesia congregata

1. Temperature strongly influences the rates of physiological processes in insects, including the herbivoreManduca sextaand its larval endoparasitoidCotesia congregata. Parasitisation byC. congregatadecreases the growth and consumption of food by larvalM. sexta. However, the effects of temperature on parasitised caterpillars and the developing wasp larvae are largely unknown.

2. In this study, parasitised and unparasitised caterpillars were reared at three constant temperatures (20, 25 and 30 °C) throughout larval development. Caterpillar mass gain and consumption were monitored daily until wandering (unparasitised control group) or wasp emergence (parasitised group) was observed. Development time and survival to emergence were measured as metrics of parasitoid performance.

3. ParasitisedM. sextadeveloped more slowly than unparasitised controls, but had similar cumulative consumption until the terminal instar. Parasitised caterpillars with relatively large parasitoid loads had higher rates of consumption and growth than those with smaller loads. Both temperature and parasitoid load strongly affected wasp success. Mean development time to wasp emergence increased with low temperatures and with large loads. The combination of warm temperature and large parasitoid loads greatly reduced wasp survival.

4. These results demonstrate the interactive effects of rearing temperature and parasitisation on host consumption and growth rates throughout larval development. In addition, wasp performance was affected by the interaction of temperature and parasitoid load size. High temperatures alter the dynamics of the interaction between the parasitoid and its caterpillar host, which could have far‐reaching impacts as the global temperatures continue to rise.

 
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NSF-PAR ID:
10458883
Author(s) / Creator(s):
 ;  ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Ecological Entomology
Volume:
45
Issue:
1
ISSN:
0307-6946
Page Range / eLocation ID:
p. 79-89
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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