Increased parasitization of California red scale in the field after exposing its parasitoid, Aphytis melinus, to a synthetic kairomone

Abstract

The introduced parasitoid, Aphytis melinus DeBach (Hymenoptera: Aphelinidae), utilizes a kairomone, Ocaffeoyltyrosine, to recognize California red scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae). Wasps used in augmentative release programs for California red scale on California citrus are reared on oleander scale, Aspidiotus nerii Bouché (Homoptera: Diaspididae), themselves reared on squash. Previous laboratory studies demonstrated that wasps reared on oleander scale but exposed to O-caffeoyltyrosine before bioassay more readily accepted California red scale covers for probing than wasps reared similarly but not exposed to O-caffeoyltyrosine. The goal of this study was to determine if wasps reared on oleander scale but exposed to O-caffeoyltyrosine actually parasitized a greater number of field-reared California red scale than unconditioned wasps. In order to distinguish between progeny of conditioned and unconditioned wasps in the field, we utilized two A. melinus strains that carried different electrophoretically distinguishable alleles. In half of the releases, Strain 'A' was conditioned to O-caffeoyltyrosine and Strain 'B' served as the control, while this pattern of conditioning was reversed for the remaining releases. Although there were differences in the rates of population growth of the two strains, whichever strain was the conditioned strain left a greater than expected number of progeny compared to the control strain in all comparisons. Exposure of A. melinus reared in commercial insectaries to O-caffeoyltyrosine prior to release may be a means to improve the effectiveness of such wasps in augmentative release programs to control California red scale.

Volatile attractants for three Pteromalid parasitoids attacking concealed spruce bark beetles

“…This would likely enhance the response ratio as in North American R. xylophagorum (Pettersson et al 2000). Pre-conditioning has been suggested as a means to improve effectiveness when releasing parasitoids as control agents against pest insects (Hare et al 1997). The synthetic baits, found to be attractive in this study, might thus enhance the parasitism ratio by pre-conditioning parasitoids to be released as control agents against scolytid pests on conifers.…”

Associative learning of host presence in non‐host environments influences parasitoid foraging

“…The innate preference of inexperienced parasitoids for hostplus non-host caterpillar-damaged plants could be caused by a quantitative difference in emitted volatiles related to caterpillar feeding, as a result of unequal numbers of caterpillars on the two plant infestation types (Geervliet et al, 1998a). Only very few previous studies have shown that insects that can learn to associate cues with the presence of their host/food in the laboratory also accordingly show altered behaviour in (semi-)field situations (Lewis & Martin, 1990;Hare et al, 1997;Raine & Chittka, 2008;Zrelec et al, 2013;Janssen et al, 2014;Kruidhof et al, 2015). Quantitative differences could also have occurred because of changed emission rates of caterpillar-related volatile compounds due to co-infestation by phloem-feeding insects such as aphids (Rodriguez-Saona et al, 2003;Zhang et al, 2013;Ponzio et al, 2016;Li et al, 2017).…”

“…Although thorough laboratory studies have identified the potential of learning by parasitoids as well as some of the underlying mechanisms Turlings et al, 1993;Vet et al, 1995;Hoedjes et al, 2011;Wäschke et al, 2013), the significance of learning in foraging under complex field conditions has seldom been studied (Lewis & Martin, 1990;Mery, 2013, but see Papaj & Vet, 1990Hare et al, 1997;Kruidhof et al, 2015). The few field studies show that both predators and herbivores have enhanced foraging success under field conditions when they associated the presence of their food with a distinct odour (Zrelec et al, 2013;Janssen et al, 2014).…”

Manipulation of Natural Enemies in Agroecosystems: Habitat and Semiochemicals for Sustainable Insect Pest Control

“…For example, Hare et al (1997) demonstrated that laboratoryreared Aphytis melinus DeBach, a parasitoid of the California red scale (Aonidiella aurantii (Maskell)), more readily parasitized hosts when exposed to the kairomone Ocaffeoyltyrosine prior to being released in the field.…”