Citricola Scale (Homoptera: Coccidae) Abundance on Chinese Hackberry and Scale Control with Spray Oil or Acephate Trunk Implants
Author: DREISTADT, STEVE H.
Source: Journal of Economic Entomology, Volume 89, Number 2, April 1996 , pp. 481-487(7)
Publisher: Entomological Society of America
Abstract:Citricola scale, Coccus pseudomagnoliarum (Kuwana), infesting Chinese hackberry, Celtis sincmis Persoon, was studied during 1991-1994 in Davis, CA. Female scale and crawler densities on untreated trees increased each year in comparison with previous years; populations of this introduced subtropical species were recovering from a population decline possibly induced by cold temperatures in northern California during the winter of 1990-1991. In California, European fruit lecanium, Parthenolecanium comi (Bouché), P. pruinosum (Coquillett), and Calico scale, Eulecanium cerasorum (Cockerell), also infest Chinese hackberry. However, citricola scale was 5-25 times more abundant than the Parthenolecanium species combined, and no calico scale were found on sample branches. Citricola scale was more abundant in the east and north tree canopy in comparison with the sunnier south canopy; abiotic mortality from hot, dry conditions may help to reduce scale populations. Transparent sticky tape traps helpl'd monitor scale crawler populations and were used to time foliar-season (control actions. The Humber of crawlers trapped depended on scale density, not sticky trap size. Crawler density peaked at 353 DD (SD = 43) above 11 accumulated from 1 March, but laboratory development rate and threshold temperature data and sampling from other locations are needed to validate this empirical model. Three control methods were equally effective: a single foliar spray of 2% superior oil, acephate implants during the foliar season, or a single application of 3% supreme oil to bark during the dormant season. Each method reduced scale populations by ≍ 50% during the season of treatment, but there was no difference among treatments 1 yr after control actions. Apparent parasitism of female citricola scale ill Davis, CA, was only ≍ 1%. Parasitism was significantly lower on treated trees.
Document Type: Research Article
Publication date: April 1, 1996
- 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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