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CHANGES IN THE SEX RATIO OF DENDROCTONUS FRONTALIS (COLEOPTERA: SCOLYTIDAE) ON PINUS TAEDA DURING THE ATTACK PROCESS

Published online by Cambridge University Press:  31 May 2012

Barry G. Hynum
Affiliation:
Texas Forest Service, Pest Control Section, Lufkin, Texas 75901

Extract

In studies of the southern pine beetle, Dendroctonus frontalis Zimm., on loblolly pine, Pinus taeda L., one of the theories about the mechanism of attack is a shift in sex ratio from 100% to 25% females (Renwick and Vité 1970). This paper reports a test of this theory using trees that were naturally infested.

Thirty-one naturally infested loblolly pine trees were observed in July 1978, near Cut-and-Shoot, 19 km east of Conroe, Montgomery County, Texas. A 0.66 m quadrat was marked off on the bole of each tree at heights of 3 m and 3.66 m. Gallery starts in the quadrat were counted and marked every 24 h on each tree. The quadrat was reduced to a 0.33 m section on the bole at heights of 3.33 to 3.66 m on a tree after the attack density reached 1 gallery/100 cm2 and to a 0.16 m section at heights of 3.50 and 3.66 m on the bole after the attack density reached 2 gallerys/100 cm2; this facilitated timely counting and stabilized error due to observer fatigue.

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1980

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References

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