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|Title:||The Influence of Weeds Associated With Reduced-Tillage Corn on a Black Cutworm Parasitoid, Meteorus Rubens (Nees Von Esenbeck), and Computer Simulation of The Consequences for Black Cutworm Damage|
|Author(s):||Foster, Michael Alexander|
|Department / Program:||Entomology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The impact of nectar-feeding at flowering weeds by Meteorus rubens on black cutworm damage to seedling corn was investigated through a combination of experimental research and computer simulation. In the laboratory, female M. rubens provided with flowering weeds lived on average 7.6 days, more than twice as long as starved wasps. Total parasitism and reproduction, 12.3 hosts and 164.7 offspring per wasp respectively, were also more than twice as great in nectar-fed wasps. In the field, wasps were visible in cages ca. 50% longer when flowering weeds were present, 6.1 versus 4.1 days. In the greenhouse, the density of nectar-fed wasps in cages was greater than that of their starved counterparts due to increased longevity. Consequently, parasitism increased from 25% to 41% and from 34% to 52% at low and moderate rates of wasp introduction into cages respectively.
An existing model for black cutworm damage was modified by adding submodels for M. rubens dynamics and parasitism. Simulations were conducted under varying conditions of tillage, pheromone trap catches of cutworm moths, and wasp emergence rates to determine the impact of nectar-feeding on cutworm damage. Wasp density was 40% greater when weeds were available to wasps as nectar sources after planting. Parasitism consequently increased from 25% to 33%, 51% to 60%, and 75% to 80% at the low, medium, and high rates of wasp emergence respectively. However, this greater parasitism reduced damage additionally by only a few %, a noneconomic effect. Despite this result, it would be premature to conclude that nectar-feeding is unimportant since the model is not yet validated. Parameter values currently used in the submodels for wasp dynamics and parasitism could cause the impact of nectar-feeding on cutworm damage to be underestimated. Validation experiments are suggested to indicate if and where model refinement is needed.
The addition of other parasitoid-tillage interactions and parasitoid species to the model is suggested to refine further its accuracy. Finally, its possible uses both in agroecosystem research and black cutworm pest management are discussed.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984.
|Date Available in IDEALS:||2014-12-16|