Diversifying the arthropod community with partridge pea: Increasing natural enemies and controlling pests in organic field corn

Background/Question/Methods

Monoculture cropping systems generate favorable conditions for the occurrence of pest outbreaks. These conditions may be exacerbated by the use of synthetic pesticides in conventional systems. Alternatively, organic growers generally rely on preventive measures such as crop rotation and other ecology-based practices to help manage pests. Given that many beneficial species use plant nectar as a food source, the maintenance of nectar-producing plants near cornfields should enrich the community of beneficial arthropods within. The purpose of this study was to examine the effects of bordering corn plots with partridge pea, Chamaecrista fasciculata (Michx.), on parasitism and predation rates of stink bugs, arthropod density and diversity, and corn quality and yield, compared with monoculture corn plots. Data were collected on predator and pest numbers, rates of stink bug egg parasitism, and corn ear damage and yield. Data on arthropods were collected for 6 weeks by visual counts, sticky card traps, and vacuum samples at research plots in Keedysville, Maryland. We hypothesized increased parasitism rates, reduced damage, and an influx of beneficial arthropods will be observed in plots with the provision of nectar. 

Results/Conclusions

Rates of parasitism were high across all stink bug egg masses found (~65%), though significant differences between treatments were not observed. The nectar provided by partridge pea may be responsible for maintaining the high parasitism rates, even with the increased numbers of stink bug egg masses found in treatment plots. Damage to corn was not significantly different between treatments. However, location of corn within plots was correlated with amount of damage observed. Partridge pea may have an amplified effect along field borders where damage appears to be greatest. Findings from this research provide valuable information to growers with respect to the use of flowering plants to help manage stink bugs and other field corn pests.