Environmental Entomology (1999) 28, 72-80

P.J. Lester, D.J. Pree, H.M.A. Thistlewood, L.M. Trevisan and R. Harmsen (1999)
Pyrethroid encapsulation for conservation of acarine predators and reduced spider mite (Acari : Tetranychidae) outbreaks in apple orchards
Environmental Entomology 28 (1), 72-80
Abstract: We examined the effects of a micro-encapsulated formulation of the pyrethroid cypermethrin on the predator Amblyseius fallacis (Garman) and the biological control of tetranychid mites. In functional response analysis, susceptible field-collected and mass-reared pyrethroid resistant strains of A. fallacis consumed similar numbers of Tetranychus urticae Koch eggs on unsprayed leaf-disks (14-16 eggs per day). Fewer prey were consumed on micro-encapsulated cypermethrin sprayed disks, but consumption was similar between strains (10.3-11.3 eggs per day). The functional response on cypermethrin EC (emulsifiable concentrate)-sprayed disks was associated with resistance. Susceptible A. fallacis mites (cypermethrin LC₅₀ = 7.2 ppm) consumed a maximum of 1.0 eggs per day; field-collected predators (LC₅₀ = 13.3 ppm) consumed a maximum of 4.0 eggs per day, and mass-reared A. fallacis (LC₅₀ = 28.2 ppm) consumed a maximum of 4.33 eggs per day. Encapsulated cypermethrin was much less toxic to predators, and was similar in toxicity between strains (LC₅₀ range = 87.0-100.4 ppm). In an experimental orchard, a commercial formulation of cypermethrin EC almost eliminated A. fallacis. On trees sprayed with the micro-encapsulated formulation, mean A. fallacis densities were reduced from 0.81 ± 0.26 per leaf to 0.26 ± 0.12 per leaf. On micro-encapsulated sprayed trees this predator density, together with the stigmaeid predator Zetzellia mali (Ewing), appeared to regulate Panonychus ulmi Koch to a peak density of 21.7 ± 11.7 per leaf, compared to 87.2 ± 15.6 per leaf on cypermethrin EC treated trees, and 10.4 ± 4.6 per leaf on unsprayed trees. The micro-encapsulated cypermethrin formulation conserved natural biological control in pyrethroid sprayed orchards better than the cypermethrin EC formulation.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Philip J. Lester, David J. Pree, Howard M.A. Thistlewood

Research topic(s) for pests/diseases/weeds:
control - general
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.
	Panonychus ulmi
	Tetranychus urticae
Neoseiulus fallacis (predator)	Tetranychus urticae
Zetzellia mali (predator)	Panonychus ulmi