From laboratory to the field: consistent effects of experience on host location by the fruit fly parasitoid Diachasmimorpha kraussii (Hymenoptera: Braconidae)

Abstract

Associative learning is well documented in Hymenopteran parasitoids, where it is thought to be an adaptive mechanism for increasing successful host location in complex environments. Based on this learning capacity, it has been suggested that providing prerelease training to parasitoids reared for inundative release may lead to a subsequent increase in their efficacy as biological control agents. Using the fruit fly parasitoid Diachasmimorpha krausii we tested this hypothesis in a series of associative learning experiments which involved the parasitoid, two host fruits (tomatoes and nectarine), and one host fly (Bactrocera tryoni). In sequential Y-tube olfactometer studies, large field-cage studies, and then open field studies, naïve wasps showed a consistent preference for nectarines over tomatoes. The preference for nectarines was retained, but not significantly increased, for wasps which had prior training exposure to nectarines. However, and again consistently at all three spatial scales, prior experience on tomatoes led to significantly increased attraction to this fruit by tomato-trained wasps, including those liberated freely in the environment. These results, showing consistency of learning at multiple spatial scales, gives confidence to the many laboratory-based learning studies which are extrapolated to the field without testing. The experiment also provides direct experimental support for the proposed practice of enhancing the quality of inundatively released parasitoids through associative learning.

Fruit fly parasitoids (Hymenoptera: Braconidae) in south‐east Queensland, Australia

“…2011b; Ero & Clarke 2012), and this may limit its utility as a biological control agent if it does not forage for particular crop types (Masry et al . 2019).…”

“…The suitability of this approach as an experimental tool for working with D. kraussii in the field is illustrated by Masry et al . (2019).…”

“…2011a; Masry et al . 2019), across suburban and peri‐urban habitats. These two habitat types, due to their difference in host plant abundance, can possibly affect the presence and activity of fruit fly natural enemies.…”

Opiine parasitoids (Hymenoptera: Braconidae) and biological control of fruit flies (Diptera: Tephritidae) in Australia: Past, present and future

“…kraussii host location and utilisation is strongly influenced by host fruit cues. Ovipositionally naive wasps demonstrate innate preferences for different fruit types (Ero & Clarke, 2012;Ero, Neale, et al, 2011), but such preferences can be changed following experience on other fruit types Masry, Cunningham, & Clarke, 2019). Orientation to uninfested fruit was not recorded in a small-cage arena (Ero, Neale, et al, 2011), but was in an olfactometer ) and a large, walkin field cage (Ero & Clarke, 2012).…”

Effect of the olive fruit size on the parasitism rates ofBactocera oleae(Diptera: Tephritidae) by the figitid waspAganaspis daci(Hymenoptera: Figitidae), and first field releases of adult parasitoids in olive grove

“…Even though parasitoid behavioral studies in the fi eld are still scarce (Randlkofer et al, 2010;Kostenko et al, 2015), host plant appears to be another important source of information for parasitoids' foraging capacity (Giunti et al, 2015;Segura et al, 2012;. Recently, it was proved that host-fruit odor learning infl uences foraging capacity of the fruit fl y parasitoid, Diachasmimorpha krausii (Hymenoptera: Braconidae), against the tephritid host fl y Bactrocera tryoni in nectarines and tomatoes (Masry et al, 2019). The role of olive trees and olive fruits on the performance of A. daci and other olive fruit fl y parasitoids remain totally unexplored, despite of the long term eff orts for the biological control of olive fruit fl y (Daane and Johnson, 2010).…”