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Fourteen genotypes (varieties) of soybean (Glycine max) were screened for levels of induced resistance to Mexican bean beetle (Epilachna varivestis) damage, and a subset of 6 of those varieties was screened for levels of constitutive resistance to Mexican bean beetles. Experiments were carried out in the greenhouse, with damage imposed by Mexican bean beetle larvae, and levels of resistance measured by a choice test bioassay with adult beetles. We found significant variation among soybean genotypes in levels of both induced and constitutive resistance. We found no significant correlation between levels of induced and constitutive resistance measured in the same genotypes. We compare these results to past work on resistance in the soybean-Mexican bean beetle system, consider the implications of variation in both types of resistance for plant-herbivore interactions in agricultural and natural systems, and discuss the relationship between induced and constitutive resistance.

Populations of mountain golden heather (Hudsonia montana), a threatened North Carolina shrub, are declining due to the suppression of natural fires and increased trampling by hikers and campers. Consequently, proposed management strategies have focused on conducting controlled burns and restricting human traffic. To help design an optimal management plan, we used demographic data from a 5-year field study of H. montana--which included a controlled burn--to construct size-based population projection matrices. Using these matrices, we projected the consequences of instituting controlled burns and hiking and camping restrictions separately and in tandem. We also determined the burn frequency that would maximize H. montana's population growth rate. Finally, we used a stochastic model to determine how environmental fluctuations could alter the efficacy of conservation measures. Our results suggest that, although neither burning nor trampling reduction alone can reverse H. montana's decline, a judicious combination of the two has an excellent chance of doing so. A burn frequency of once every 6-8 years should maximize H. montana's population growth, although the interburn interval could be increased to 12-16 years without significantly jeopardizing the success of the management plan. Our results show that, even with the limited data available, size-based projection matrix models can be useful tools for identifying promising combinations of multiple management strategies for most threatened plants.