Environmental Entomology (1992) 21, 975-982

Vernard R. Lewis (1992)
Within-tree distribution of acorns infested by Curculio occidentis (Coleoptera: Curculionidae) and Cydia latiferreana (Lepidoptera: Tortricidae) on the coast live oak
Environmental Entomology 21 (5), 975-982
Abstract: Terminal shoots from coast live oaks, Quercus agrifolia Nee, were sampled to determine the abundance and spatial distribution of acorns infested by the filbert weevil, Curculio occidentis (Casey), and the filbertworm, Cydia latiferreana (Walsingham), at a site in northern California during 1989. Nine sampling strata in the tree crown were vertically aligned into blocks of three, each facing a different compass direction (NE, S, and NW). Overall, 25% of all acorns examined on shoots of sample trees revealed signs of insect-boring activity. Acorn numbers- were most abundant in May and logarithmically declined throughout the season. The frequency of insect-infested acorns on shoots during the season resembled a random distribution; however, this resemblance was not significant. Peak numbers of infested acorns appeared in mid-September. Within crowns, most acorns occurred in sampling strata within the south-facing section. Significantly more infested acorns occurred in sampling strata within the northeasterly and south-facing sections of the crown. Dissection of 501 acorns revealed infestation rates of 38%. Of those acorns found to contain insect larvae, 66% contained C. occidentis and 27% contained C. latiferreana. Possible mechanisms for explaining the dissimilar distribution of total and infested acorns within crown strata are discussed. The implications of these findings to the development of sampling schemes for ecological studies of acorn and acorn-boring insects are also discussed.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Vernard R. Lewis

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
surveys/sampling/distribution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Cydia latiferreana	Oak (Quercus)	U.S.A. (SW)
	Curculio occidentis	Oak (Quercus)	U.S.A. (SW)