Journal of Economic Entomology (1995) 88, 232-236

J.E. Baker (1995)
Stability of malathion resistance in two hymenopterous parasitoids
Journal of Economic Entomology 88 (2), 232-236
Abstract: Malathion resistance documented in a field strain of Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) collected in September 1992 near Bamberg, SC, was stable after 23 generations of laboratory rearing with no selection pressure. F₂₃ progeny of this parasitoid strain were 2,800-fold resistant to malathion relative to a susceptible laboratory (Savannah) strain and 200-fold more tolerant of malathion than the field strain of the insect host Sitophilus oryzae (L.) (Coleoptera: Curculionidae) with which they were collected. Seven cycles of laboratory selection with malathion, chlorpyrifos-methyl, and pirimiphos-methyl did not increase resistance levels in the Bamberg strain of A. calandrae to these grain protectants. Malathion resistance in F₂₁ male and female progeny of a field strain of Bracon (Habrobracon) hebetor Say (Hymenoptera: Braconidae) collected in South Carolina was not significantly different from that of F₆ progeny. However, LT₅₀s determined in a serial-time bioassay were 0.2-fold lower and may indicate a slight decline in resistance following 15 generations of laboratory rearing. Little is known about the mechanisms or genetics of the malathion resistance in these two parasitoids. Nevertheless, the stability of the resistances documented in this study, particularly in A. calandrae, will facilitate the incorporation of these parasitoid strains into integrated biological-chemical control programs for stored-product insect pests.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
resistance to pesticides

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Sitophilus oryzae
Anisopteromalus calandrae (parasitoid)	Sitophilus oryzae		U.S.A. (SE)
Habrobracon hebetor (parasitoid)			U.S.A. (SE)