Effects of bean leaf beetle, Cerotoma trifurcata (Forster), (Chrysomelidae: Coleoptera), larval feeding and soybean cyst nematode, Heterodera glycines Ichinohe, (Heteroderidae: Nematoda), on two indeterminate soybean, Glycine max (L.) Merrill, cultivars
Abstract
Greenhouse and caged field microplot experiments were conducted during 1991-1994 to evaluate the effects of bean leaf beetle (BLB), Cerotoma trifurcata (Forster), larval feeding and soybean cyst nematode (SCN), Heterodera glycines Ichinohe, on two indeterminate soybean, Glycine max (L.) Merrill; cultivars, and interactions among them, on soybean root growth, nodule development, nitrogen fixation, soybean plant top growth, and yield. Treatments were combinations of SCN, BLB, and soybean cultivars. SCN treatments were applied to the soil before planting and BLB treatments were imposed at early vegetative and early reproductive stages of soybean development. BLB treatments resulted in lower plant top weights and root weights. 'Fayette' plants were more adversely affected by BLB treatments than were 'Union' plants. Fewer BLB eggs hatched in pots with 'Union' plants. BLB treatments decreased numbers of nodules, but increased rates of nitrogen fixation. SCN treatments reduced top weights and heights, and root weights of the SCN-susceptible 'Union' plants. Nodule weights and numbers varied in responses to SCN treatments depending upon experiment. In the field experiments, BLB and SCN each adversely affected above-ground plant growth characteristics. Similarly, both adversely affected roots, nodules, and ethylene production, with a few exceptions. Effects on yield, by each pest, were variable, depending upon year. BLB and SCN adversely affected nodule development where each occurred alone, but there was an antagonism between the two pests so that one pest decreased the adverse effect that the other had on nodule development and ethylene production. BLB was detrimental to reproduction and development of SCN and SCN moderated effects of BLB on nodule weights.
Degree
Ph.D.
Advisors
Edwards, Purdue University.
Subject Area
Entomology|Agricultural engineering|Agronomy
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