The economic contribution of a naturally occurring insect predator to the control of the Mexican bean beetle Epilachna varivestis Mulsant on Indiana soybeans
Abstract
This research is in two parts. The first concerns the economic contribution of a naturally occurring insect predator (the Spined Soldier Bug, Podisus maculiventris) to the control of the Mexican Bean Beetle (Epilachna varivestis), the most important insect pest of soybeans in Indiana. The simulations performed in this research indicate that the economic contribution of naturally occurring populations of the Spined Soldier Bug (SSB) is about $0.37 per hectare. Artificially augmented SSB populations can make substantially higher contributions---more than \$15/ha, in some cases. However, the cost of artificially augmenting SSB populations is unknown. The most likely use of augmented SSB populations is in the production of organic soybeans, since augmented SSBs cannot provide the same level of pest control as insecticides. The second part of the research involved evaluation of 60 different MBB control strategies using naturally occurring and augmented SSB populations. Two soybean cultivars, five insecticide/scouting combinations, and three planting dates were evaluated in addition to the two SSB population levels. Expected net returns, the mean squared deviation of those returns, and expected insecticide applications were calculated for each strategy over 110 states of nature. In addition, econometric and direct search techniques were used to try to find more profitable strategies than those in the initial group of sixty. A relatively small number of strategies proved profit maximizing under the research assumptions. The most profitable strategies were found using the direct search technique. Frontier diagrams of "efficient" strategies were constructed and tradeoffs explored between expected net returns, mean squared deviation of returns, and expected insecticide applications. When criteria other than profit maximization were included in the analysis, the number of efficient strategies increased to 22 of 60.
Degree
Ph.D.
Advisors
Lovejoy, Purdue University.
Subject Area
Agricultural economics|Entomology
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