Testing the habituation assumption underlying models of parasitoid foraging behavior

Abstract

Habituation, a form of non-associative learning, has several well-defined characteristics that apply to a wide range of physiological and behavioral responses in many organisms. In classic patch time allocation models, habituation is considered to be a major mechanistic component of parasitoid behavioral strategies. However, parasitoid behavioral responses to host cues have not previously been tested for the known, specific characteristics of habituation. Here, we tested whether the foraging behavior of the egg parasitoid Trissolcus basalis shows specific characteristics of habituation in response to consecutive encounters with patches of host (Nezara viridula) chemical contact cues (footprints), in particular: (i) a training interval-dependent decline in response intensity, and (ii) a training interval dependent recovery of the response. As would be expected of a habituated response, wasps trained at higher frequencies decreased their behavioral response to host footprints more quickly and to a greater degree than those trained at low frequencies, and subsequently showed a more rapid, although partial, recovery of their behavioral response to host footprints. In contrast to previously studied forms of parasitoid memory (i.e., from associative learning), this putative habituation learning could not be blocked by cold anesthesia, ingestion of an ATPase inhibitor, or ingestion of a protein synthesis inhibitor. Our study provides support for the assumption that diminishing responses of parasitoids to chemical indicators of host presence constitutes habituation as opposed to sensory fatigue, and may indicate that the underlying mechanisms differ from other, better-studied forms of parasitoid learning.

The invasive stink bug Halyomorpha halys affects the reproductive success and the experience-mediated behavioural responses of the egg parasitoid Trissolcus basalis

“…rewarded experience) (Peri et al 2006(Peri et al , 2016. The mechanism underlying parasitoids' responsiveness to footprints has been shown to have several characteristics of habituation, a form of non-associative learning (Abram et al 2017).…”

“…These characteristics include a decrease of the response intensity following unrewarded experiences in an interval-dependent manner, i.e. wasps display a decline in response which is more rapid and pronounced when footprints are re-encountered without hosts at shorter intervals (Abram et al 2017).…”

Biological control of invasive stink bugs: review of global state and future prospects

“…Parasitoid recruitment using semiochemicals can be affected by the experience of the foraging females, for example when the hosts are scarce or lacking. Without the reward of suitable host eggs, scelionid parasitoid females were shown to reduce their responses to semiochemicals due to habituation (Peri et al, 2006(Peri et al, , 2016Abram et al, 2017a). Additionally, most parasitoids are more dependent on other cues than those from the host-plant complex, such as floral odours from nectar plants.…”