Effects of feeding of the two spotted spider mite, Tetranychus urticae Koch, on leaf and seed composition and dry matter accumulation in two soybean, Glycine max (L.) Merr., cultivars previously found to respond differently to mite infestation were investigated to gain a greater understanding of resistance mechanisms in soybeans to this wide host range plant pest. The two soybean cultivars, 'Bonus' and 'Williams', were infested with mites at the V3, V6, and R2 stages of development with 0, 10, and 200 mites per first fully expanded trifoliolate leaf. A relatively greater reduction in dry matter accumulation was seen in 'Williams' than in 'Bonus' at the same mite population level on the foliage. However, mite population increase was significantly lower on 'Williams' than on 'Bonus'. Increasing mite infestation levels caused a slight increase in total soluble sugars and starch and a small decrease in total nitrogen and phosphorus levels of the leaves of both cultivars. Mite infestation had no effect on composition of seeds. Increasing mite damage caused a large reduction (55.26%) in leaf chlorophyll content and an even more dramatic loss (79.3%) in leaf carotenoid content with a greater loss in 'Williams' at the low mite infestation level. Results of these studies indicated that at least part of the increased resistance of 'Williams' to damage from T. urticae was due to a greater hypersensitive response of 'Williams' to mite attack. This response increased oxidizing conditions in the leaves, resulting in an extensive loss of carotenoids and chlorophyll. Increased oxidizing conditions in 'Williams' decreased mite population increases to a greater extent than it decreased net photosynthesis (dry matter accumulation).
Document Type: Research Article
Publication date: August 1, 1986
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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.