Quantifying the impact of insect predators and parasitoids on populations of the apple ermine moth,Yponomeuta malinellus(Lepidoptera: Yponomeutidae), in Europe

Abstract

Life tables were developed to assess the significance of natural enemies on the dynamics of apple ermine moth, Yponomeuta malinellus Zeller, in southwestern Germany and to select parasitoid species for use in the biological control of this pest in Canada. During the study from 1993 to 1995 the abundance of Y. malinellus varied from 1.5 to 4.3 tents per 100 leaf clusters indicating that this was a non-outbreak population. From the life tables it was evident that the impact of egg predators accounted for 25^3% of the total generational mortality of Y. malinellus, more than any other known mortality factor. Percent parasitism varied from 18 to 30%, but the impact of parasitoids in relation to the total generational mortality of Y. malinellus from the life tables was remarkably constant at 11-14%. The loss of potential fecundity had an important influence on the generational mortality of Y. malinellus, but declined from 27% to 15% over the course of this study. This decline corresponded with a rise in the net rate of increase Ro from 1.35 in 1993 to 6.8 in 1995, despite the impact of insect predators and parasitoids on the generational mortality. Yponomeuta malinellus was attacked by five different obligate primary parasitoids, a single obligate hyperparasitoid, and three facultative hyperparasitoids. Of these, the oligophagous egg-larval parasitoid Ageniaspis fuscicollis Dalman (Encyrtidae) and the oligophagous larval-pupal and pupal parasitoid Herpestomus brunnicornis Gravenhorst (Ichneumonidae) were selected as potential biological control agents for Canada due to a minimal degree of interspecific competition.

Parasitoid complex of the bird cherry ermine moth Yponomeuta evonymellus in Korea

“…Similarly, Dijkerman (1987) reported that the low degree of parasitization by Ageniaspis fuscicollis was a general phenomenon known from Yponomeuta evonymellus. However, the wasp has been reported to be the most effective parasite at high host density, causing considerable reduction in Yponomeuta malinellus populations in both Europe and Korea (Kuhlmann et al 1998b;Lee & Pemberton 2005).…”

Constructing life‐tables for the invasive maize pestDiabrotica virgifera virgifera(Col.; Chrysomelidae) in Europe

“…Despite this potential underestimation, it is still likely that the D. v. virgifera populations demonstrated a great failure to realize their potential fecundity; a situation that has been commonly reported for many other pest insects (Banerjee 1979; Bellows et al. 1992; Kuhlmann et al 1998). This is likely the main reason that D. v. virgifera populations are often far below their potential (Hein and Tollefson 1987).…”

Choosing a place to grow. Importance of within‐plant abiotic microenvironment for Yponomeuta mahalebella

“…Thus, the effect of orientation in survival was not directly related to parasitoid success, e.g. affecting parasitoid behaviour as reported for other species (Kuhlmann, 1995). It could be that caterpillars from tents in south-east orientation presented higher vigour because of better developmental conditions, but more data are needed to test this hypothesis.…”