No ovipositional preference was shown by spruce spider mites, Oligonychus ullunguis (Jacobi), with respect to compass direction or the upper, middle, or lower strata of Colorado spruce, Picea pungens (Engelmann). However, along the axes of host plant limbs, eggs were deposited significantly farther from the center of the plant on tile south and east sides than on the north and west sides. Eggs were deposited significantly farther from the center of the host plant in tile lower stratum than in the upper and middle strata. Degree day accumulations, using 2 lower developmental thresholds, were used to describe eclosion of diapausing eggs. Mean degree-day accumulations (±SD) from 1 March to eclosion were 143.3 ± 30.1 base 7.1 and 170.1 ± 29.6 base 5.6. These means coincided well (=5 d) with observed hatching times in the field in 1993 and 1994. A In-probit transformation of the data and regression analysis revealed no significant difference between the accuracy of either model relative to field observations. However, the model using tile lower of the 2 developmental thresholds (5.6) provided a better fit with data gathered in the lab (r2 = 0.94, MSE = 0.114), suggesting that 5.6 is a better base temperature for predicting emergences based on degree-days.
Document Type: Research Article
Publication date: April 1, 1996
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.