Effects of Four Pyrethroids on Scale Insect (Homoptera) Populations and Their Natural Enemies in Loblolly and Shortleaf Pine Seed Orchards


Source: Journal of Economic Entomology, Volume 85, Number 4, August 1992 , pp. 1246-1252(7)

Publisher: Entomological Society of America

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A loblolly pine, Pinus taeda L., seed orchard in Georgia received five applications of bifenthrin, fenvalerate, esfenvalerate, and perrnethrin in 1988 and 1989, and a shortleaf pine, P. echinata Miller, seed orchard in Oklahoma was treated five times in 1988 with the same insecticides, excluding perrnethrin. Infestations of striped pine scale, Toumeyella pini (King), and the mealybug Oracella acuta (Lobdell) appeared at the Georgia orchard after the third 1988 applications. Bifenthrin plots generally had numerically lower infestation levels than did plots treated with the other pyrethroids, and numbers oflive females in the bifenthrin plots were not significantly different from numbers in unsprayed plots. In 1989, a moderate striped pine scale infestation continued, mealybugs were scarce, and an outbreak of Pseudophilippia quaintancii Cockerell began. Bifenthrin plots again had lower numbers of scale insects than the other insecticide-treated plots. A severe outbreak of pine tortoise scale, Toumeyella paroicornis (Cockerell), began after two insecticide applications at the Oklahoma orchard. By September, populations were lowest in control plots, intermediate in bifenthrin plots, and highest in plots treated with the other insecticides. In June 1989, heavy infestations were still present, even though spraying had been discontinued. By the end of July, the populations had collapsed, apparently as a result of natural enemies and intraspecific competition. Large numbers of the parasites Metaphycus spp. and Coccophagus spp. were collected from old-growth foliage, whereas more predators were reared from new growth. Parasitism rates were low in both orchards during the months of the spray applications. Unsprayed plots generally had more spiders than had treated plots, and fenvalerate plots had fewer lacewings.

Document Type: Research Article

Publication date: August 1, 1992

More about this publication?
  • Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.
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