A field study was conducted from 1991 to 1993 to describe the dynamics of the seven-spotted lady- beetle, Coccinella septempunctata L. in the potato ecosystem in northern Maine. Barley and potato were the crop habitats studied. In potato, the abundance of C. septem-punctata was evaluated relative to three pest manage-ment strategies (biological, conventional, reduced input), two potato cultivars (Superior and Atlantic), and two soil fertility management treatments (synthetic fertilizer vs. manure and potato compost). C. septempunctata was more abundant in barley than in potato in 1992 and 1993, the two years this comparison was evaluated. Adult abundance in the barley crop, in 1992 and 1993, was negatively correlated with the abundance of aphid prey, while in potato, in 1992, a negative correlation, but delayed by one to two weeks, was found between this predator’s abundance and aphid prey. Pest management strategies influenced the abundance of C. septempunctata adults within the potato crop in two of the three years. Significantly higher densities were found in biological pest management plots than in low input or conventional pest management plots. Soil fertility and potato cultivar also had an influence on C. septempunctata adult abundance, which was correlated with aphid densities. Also, C. septempunctata adults were more abundant on the potato cultivar Superior, supplemented with nitrogen compared to the same cultivar grown in soil amended with manure and compost and the potato cultivar Atlantic, grown under both soil management treatments in both 1992 and 1993.

¹Maine Agricultural Experiment Station Journal Article no. 1989