Evaluating sub-lethal effects of orchard-applied pyrethroids using video-tracking software to quantify honey bee behaviors" (2015). Faculty Publications: Department of Entomology. 377.

1. This study investigated the effect of temperatures ranging from 10.8 to 34.2 ∘ C on seven walking parameters of an egg parasitoid, Anaphes listronoti. Those responses were compared with a theoretical kinetic model in order to disentangle the kinetic response of the insect from its integrated response.2. Walking speed increased continuously with temperature, but walking distance and duration were maximised between 25 and 30 ∘ C, and decreased at higher and lower temperatures. At the lowest temperature, females unexpectedly walked a greater distance and for a longer duration in comparison with intermediate temperatures.3. The number of walking bouts followed the same polynomial trend as walking distance and duration, with a maximum between 30 and 35 ∘ C. The duration of walking bouts was maximised at 20 ∘ C and decreased at lower and higher temperatures, whereas the duration of resting bouts linearly decreased with increasing temperature. There was no effect of temperature on the turning rate of females.4. For A. listronoti, walking speed and duration of resting bouts followed the kinetic response, but the other behavioural components did not, especially at the lowest and highest temperatures. Walking distance and duration were higher than expected under the kinetic response at 10.8 ∘ C and lower than expected at 34.2 ∘ C. This pattern suggests an integrated response combining behavioural escape from adverse temperature and energy saving.5. This detailed analysis of the walking behaviour of A. listronoti illustrates the complexity of insect behavioural responses to temperature and the difficulty involved in assessing underlying mechanisms.

The effect of temperature during host patch exploitation by parasitoids remains poorly understood, despite its importance on female reproductive success. Under laboratory conditions, we explored the behaviour of Anaphes listronoti, an egg parasitoid of the carrot weevil, Listronotus oregonensis, when foraging on a host patch at five temperatures. Temperature had a strong effect on the female tendency to exploit the patch: A. listronoti females parasitized more eggs at intermediate temperature (20 to 30°C) compared to those foraging at the extreme of the range (15.9°C and 32.8°C). However, there was no difference in offspring sex-ratio and clutch size between temperature treatments. Mechanisms of host acceptance within a patch differed between temperatures, especially at 32.8°C where females used ovipositor insertion rather than antennal contact to assess whether a host was already parasitized or not, suggesting that host handling and chemical cues detection were probably constrained at high temperature. Females spent less time on the host patch with increasing temperatures, but temperature had no effect on patch-leaving rules. Our results show that foraging A. listronoti females behave better than expected at sub-optimal temperatures, but worse than expected at supra-optimal temperatures. This could impair parasitoid performance under ongoing climate change.