Effects of soil type and moisture on emergence of tuber flea beetles, Epitrix tuberis (Coleoptera: Chrysomelidae) from potato fields

The numbers of adult tuber flea beetles, Epitrix tuberis Gentner, emerging from different soil types in the lower Fraser Valley of British Columbia were compared in 1987 and 1988. Overwintered beetles (P1) were released at known densities onto caged Russet Burbank potato plants grown in soils with different inorganic, organic, and moisture characteristics. The time from the introduction of P1 beetles in June to the mean initial emergence of first generation (F1) beetles ranged from 38 to 47.2 days during the two years of study. The female:male sex ratio of 2210 F1 beetles was 1:0.94, with a slight but significant bias in females early in the emergence period. Although significantly more F1 beetles emerged from some highly organic soils than from some mineral soils in both years, inorganic, organic and moisture factors of the test sites did not correlate consistently with the emergence of F1 beetles in time or numbers. F1 emergence from mineral soils was never significantly greater than that from highly organic soils. This work indicates that the economic injury level derived from studies of P1 beetles in highly organic soils could be applied to other soil types with minimal risk to potato crops.