INTERACTIONS BETWEEN BACILLUS THURINGIENSIS BERLINER AND APANTELES FUMIFERANAE VIER. (HYMENOPTERA: BRACONIDAE), A PARASITOID OF THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEM.) (LEPIDOPTERA: TORTRICIDAE)

Abstract

Can. Ent. 122: 585-594 (1990) Interactions between Bacillus thuringiensis Berliner and Apanteles fumiferanae Viereck as mortality factors of the spruce budworm, Choristoneurafumiferana (Clemens), were investigated by placing parasitized and nonparasitized budworm larvae on foliage with and without spray deposits of a commercial formulation of B. thuringiensis. The effect of larval age (and, thus, the timing of spray applications) was examined by using peak thud-instar and peak fourth-instar larvae. We demonstrated that parasitized larvae are more likely to survive exposure to B. thuringiensis because they feed less than nonparasitized larvae and are thus less likely to acquire a lethal dose of the bacterium. THE CANADIAN ENTOMOLOGIST July/August 1990 stade. La survie amtlior& de parasitoides a compenst la mortalitt rtduite des arrosages retardks de B. thuringiensis. Nous avons conclu que I'application de B. thuringiensis aux populations larvaires de la tordeuse la cime du quatrihme stade ou plus tard complkterait au lieu de contrarier les effets avantageux de A. fumiferanae. Les implications a I'tgard des straegies de maniement de la tordeuse sont discutkes. THE CANADIAN ENTOMOLOGIST

Synergistic interaction between sublethal doses of Bacillus thuringiensis and Campoletis chlorideae in managing Helicoverpa armigera

“…If Bt kills the host too quickly or retards the growth very severely, the parasitoid does not have sufficient resources to develop. For example, the population of Apanteles fumiferanae, a parasitoid of spruce budworm, was reduced by 50-60% because of lack of parasitoid emergence before host death (Nealis and Van Frankenhuyzen 1990).…”

Insect parasitoids : a Canadian perspective on their use for biological control of forest insect pests

“…Nealis and van Frankenhuyzen (1990) hâve shown that higher levels of parasitism of young spruce budworm larvae can be achieved if Bt is applied against the host larva in its 4 th rather than 3 rd instar. This delay of approximately one week in the field provides sufficient time for the parasitoid, Apanteles fumiferanaeViereck [Hymenoptera: Braconidae], to émerge from the host and thus, avoid indirect mortality due to the insecticide application.…”

Natural enemies and forest pest management

“…Certain microbial insecticides such as Bacillus thuringiensis (Bt) have the advantage of being most toxic to herbivorous insects and relatively harmless to entomophagous insects (Hassan et al 1987). Nealis and van Frankenhuyzen (1990) have shown that because parasitized spruce budworm eat less than healthy budworm, parasitized individuals are actually less vulnerable to Bt than healthy larvae. Spraying Bt on a population comprised of parasitized and healthy budworm leaves a disproportionately high number of parasitized budworm.…”

“…One approach is the development of phenology models for both the pest and its natural enemies to devise a spray schedule that maximizes the conservation of beneficial insects without losing substantial efficacy of the spray. Such an approach was illustrated by Nealis and van Frankenhuyzen (1990) and has been demonstrated successfully in an experimental spray program (Nealis, van Frankenhuyzen and Cadogan, unpublished).…”