Multiparasitism of Choristoneura fumiferana by the ichneumonid Tranosema rostrale and the tachinid Actia interrupta: occurrence in the field and outcome of competition under laboratory conditions

Abstract

Tranosema rostrale (Brishke) (Hymenoptera, Ichneumonidae) and Actia interrupta Curran (Hymenoptera: Tachinidae) are the two endoparasitoids most frequently encountered in low-density populations of the spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera, Tortricidae), in the Quebec City region. Monitoring of attack rates of implanted C. fumiferana larvae at two different study sites suggested the possible existence of competition between the two parasitoids, with A. interrupta seemingly displacing T. rostrale. Here, we show that multiparasitism involving these two species does occur in the field, but at a frequency too low to explain the seasonal pattern of decline in apparent parasitism by T. rostrale that accompanies the rise of A. interrupta attack rates. We also provide preliminary evidence, from laboratory experiments, that A. interrupta has a competitive advantage over T. rostrale and that the success of parasitism by A. interrupta may be enhanced by prior parasitism by T. rostrale under certain conditions, possibly due to the presence of the latter species' polydnavirus. In addition, we describe a PCR-based method that we developed to help detect the presence of T. rostrale eggs which often escape detection by simple visual examination of the dissected host larvae; DNA sequences specific to the polydnavirus injected by the female wasp at the time of oviposition can be readily amplified from whole host larvae.

Parasitism of the Spring Leafroller (Lepidoptera: Tortricidae) Complex in Organically Managed Apple Orchards in The North Okanagan Valley of British Columbia

“…in the Netherlands (Evenhuis & Vlug 1983), C. rosaceana in Quebec (Cusson et al 1998) and Archips argyrospilus in Quebec (Paradis & LeRoux 1962). It is also a known parasitoid of the spruce budworm, Choristoneura fumiferana (Clemens) (Huber et al 1996, Cusson et al 2002 which is common on conifers neighbouring some orchards in this study. In addition, two unidentified species of Temelucha Fö rster (Cremastinae) were found in what was presumed to be C. rosaceana or P. limitata larvae.…”

Evaluation of sequential exposure of irradiated hosts to maximize the mass rearing of fruit fly parasitoids

“…The main problem detected was multiparasitism, which probably increased host mortality. The phenomenon of multiparasitism is common in nature (Bautista and Harris 1997;Cusson et al 2002;Ribeiro, d'Almeida, and Pinto de Mello 2005), and several cases have been reported in fruit flies (Pemberton and Willard 1918;van den Bosch and Haramoto 1953;Palacio, Ibrahim, and Ibrahim 1991;Leyva 1982;Bautista and Harris 1997). In the present study, superparasitism by C. haywardi (an endoparasitoid) was relatively low, more frequent in Dirhinus sp., and most common in E. sivinskii.…”

“…In the present study, superparasitism by C. haywardi (an endoparasitoid) was relatively low, more frequent in Dirhinus sp., and most common in E. sivinskii. This situation was perhaps caused by the paucity of interspecifically recognized markers that allow ovipositing females to discriminate between parasitized and unparasitized hosts (Godfray 1994;Cusson et al 2002). However, in our studies, oviposition by pupal parasitoids, while present under all conditions, Biocontrol Science and Technology 105 was less frequent in pupae that had been previously superparasitized by D. longicaudata (puparia with multiple oviposition scars).…”

Interspecific competition between two endoparasitoids Cotesia vestalis (Hymenoptera: Braconidae) and Oomyzus sokolowskii (Hymenoptera: Eulophidae)

“…vestalis was mainly related to wasp‐associated factors (Bai et al, 2003). Similarly, when multiparasitism of Choristoneura fumiferana by the ichneumonid Tranosema rostrale and the tachinid Actia interrupta occurred, the PDV of ichneumonid played a key role in affecting the outcome of competition (Cusson et al, 2002). However, our observations are not in agreement with those reported by Talekar and Hu (1996) and Talekar (1997).…”