Direct and indirect effects of the striped cucumber beetle (Acalymma vittatum) on the reproduction of butternut squash (Cucurbita moschata)
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Herbivores and pollinators can be important determinants of yield. Striped cucumber beetles are found in flowers of butternut squash and are considered to be an agricultural pest. However, the effect of cucumber beetles in flowers on crop yield is unknown. The striped cucumber beetle may reduce squash reproduction directly through florivory or indirectly by influencing pollinator preferences. We manipulated beetles in flowers and pollen loads and measured fruit set to distinguish between these direct and indirect impacts. Over 50 hours of pollination data were collected over the summer of 2009 over 18 days to determine if beetles deterred pollinators. The percent damage on flowers increased for both male flowers (p<.001) and female flowers (p<.0001) in treatment groups with beetles. Despite this significant difference in damage, initial analyses suggests that beetles in flowers do not affect yield or pollinator preferences. This could be important information for farmers, potentially influencing pest management decisions. If beetles are not reducing yield through squash flowers, farmers may not be concerned with these beetles in their flowers and perhaps management should be focused on early leaf damage and also belowground, when beetles are in their larval stage and feed on roots. Reducing pesticide use in flowers could also avoid potential adverse affects on bee populations that are in decline.