Effects of Rewarding and Unrewarding Experiences on the Response to Host-induced Plant Odors of the Generalist Parasitoid Cotesia marginiventris (Hymenoptera: Braconidae)

Abstract

Associative learning is known to modify foraging behavior in numerous parasitic wasps. This is in agreement with optimal foraging theory, which predicts that the wasps will adapt their responses to specific cues in accordance with the rewards they receive while perceiving these cues. Indeed, the generalist parasitoid Cotesia marginiventris shows increased attraction to a specific plant odor after perceiving this odor during contact with hosts. This positive associative learning is common among many parasitoids, but little is known about the effects of unrewarding host searching events on the attractiveness of odors. To study this, preferences of female C. marginiventris for herbivore-induced odors of three plant species were tested in a six-arm olfactometer after the wasps perceived one of these odors either i) without contacting any caterpillars, ii) while contacting the host caterpillar Spodoptera littoralis, or iii) while contacting the non-host caterpillar Pieris rapae. The results confirm the effects of positive associative learning, but showed no changes in innate responses to the host-induced odors after "negative" experiences. Hence, a positive association is made during an encounter with hosts, but unsuccessful host-foraging experiences do not necessarily lead to avoidance learning in this generalist parasitoid.

Agathis bishopi (Hymenoptera: Braconidae) as a Potential Tool for Detecting Oranges Infested with Thaumatotibia leucotreta (Lepidoptera: Tortricidae)

“…This behavioural response of female A. bishopi to its host habitat cues (i.e. increased responsiveness due to prior exposure to host cues) compares well with other braconid parasitoids of fruit feeding hosts (Mattiacci et al 1999;Gandolfi et al 2003;Costa et al 2010;Canale and Benelli 2011).…”

Learning the way to blood: first evidence of dual olfactory conditioning in a blood-sucking insect, Rhodnius prolixus. I. Appetitive learning

“…Learning and memory, understood as the insects' behavioural adjustments based on previous experience, are two mechanisms that could help them to integrate and adapt to local variations in their environment (Dukas and Bernays, 2000;Menzel, 2001). These mechanisms and, more precisely, associative learning, have been particularly well studied in bees and fruit flies, which can be considered as classical models (Siwicki and Ladewski, 2003;Srinivasan, 2010), and have also been described in other insects such as cockroaches, caterpillars and hymenopteran parasitoids (Alloway, 1972;Papaj and Lewis, 1993;Horridge, 1997;Wackers and Lewis, 1999;Lucchetta et al, 2008;Costa et al, 2010). These studies have provided large amounts of information on the genetic and neurobiological bases of learning as well as on the complexity of insects' cognitive abilities (Bitterman et al, 1983;Bitterman, 1996;Dubnau and Tully, 1998;Xia et al, 1998;Menzel, 1999;Menzel et al, 2007;Menzel and Giurfa, 2001;Giurfa, 2003;Carcaud et al, 2009).…”

A tritrophic signal that attracts parasitoids to host-damaged plants withstands disruption by non-host herbivores

“…This may also allow parasitoids to reduce the impact of the negative interference of non-host herbivores on host-induced volatiles [17]. …”

“…Following this, we specifically tested if C. marginiventris is able to distinguish HIPVs from hosts ( E. variegatus ) and non-host ( S. littoralis ) and if simultaneous E. variegatus attack affects the attractiveness of S. littoralis infested plants. The assays presented here took into account the effect of previous encounters with hosts and host-associated odours, which can strongly affect the responses of parasitoids, including C. marginiventris [16,17], through associative learning [28]. …”