HP10 New Advances in Estimating Effects of Toxicants on Populations
D135-136
1:20 PM - 5:20 PM, Thursday
() Insect population response to selective pesticides and vegetation diversity: field studies.
Banks, John1, 1 University of Washington, Tacoma, Tacoma, WA, USA
ABSTRACT- I discuss the results of field experiments aimed at exploring the interaction of selective pesticide use and vegetation diversity and on aphid population dynamics. In particular, I established field plots of broccoli subjected to (i) no pesticide spray, (ii) low concentration pesticide spray, or (iii) high concentration pesticide spray, surrounded by (a) bare ground or (b) weedy margins. Weekly population counts of aphids feeding on broccoli in the different treatment plots were analyzed using standard analysis of variance (MANOVA) as well as a more sophisticated mathematical approach that fits population dynamics models to aphid data. Both analyses revealed a synergistic interaction between margin type and pesticide disturbance for one of the pesticides, imidacloprid, suggesting that effects of selective pesticides may be enhanced by increased within-field vegetation diversity. I discuss the implications of these findings for assessing the impact of selective pesticides, and weigh the relative merits of each of the analytical approaches in furthering our understanding of pesticide effects in combination with cultural controls.
Key words: Aphididae, Brassica, optimization, imidacloprid