Striped cucumber beetle, Acalymma vittatum (Fab.), artificial egg infestations and subsequent larval development and damage to watermelon, Citrullus lanatus (Thunb.) Matsum & Nakai, in greenhouse and field conditions

Paul Erich Rensner, Purdue University

Abstract

Field experiments in 1986 and 1987 were designed to determine the effects of striped cucumber beetle (STCB), Acalymma vittatum, larval feeding on watermelon, Citrullus lanatus, roots. Mulched and unmulched seedlings of the watermelon variety 'Crimson Sweet' were artifically infested with 0, 75, or 150 STCB eggs 3, 9, or 3 & 9 days after transplanting (DAT). Mulched plants had significantly greater vine length, 27 and 29 DAT, and melon numbers and weight per plant, than the unmulched plants in both years. Plants which were uninfested had greater vine length and yield parameters than infested plants. Seedlings which were infested soon after transplanting, 3 or 3 & 9 days, also had reduced vine length and yield parameters when compared to uninfested seedlings or those infested 9 DAT. Field investigations were undertaken in 1987 and 1988 to determine the effects of STCB larval feeding on the roots of watermelon varieties. Seedling plant growth and development and harvest yields were measured on five watermelon varieties infested with 0, 75, or 150 STCB eggs 3, 9, or 3 & 9 DAT. Overall, the STCB egg infestations affected the watermelon growth parameters. Vine lengths from uninfested plants and those infested with 75 eggs 9 DAT appeared to withstand the infestations, while those infested soon after transplanting, 3 or 3 & 9 days, suffered delayed growth, and the high egg rate of 150 eggs only increased root damage. Early season varieties appeared to tolerate larval feeding early in the season, but by seasons end, yields were not different from the later maturing varieties. Greenhouse experiments were designed to investigate the effects of STCB larvae on the early growth and development of watermelon varieties. Four watermelon varieties were infested with 0, 37, 75, 150, 225, and 300 eggs per plant 5 DAT. STCB larval feeding damage was assessed by measuring stem length, and stem and root dry weights 16 days after the infestations occurred. In addition, stem length and stem dry weight to root dry weight ratios were calculated. STCB larval damage to watermelon seedlings occurred in significant linear relationships between the egg levels and growth parameters. The parameters showed differences in response below 37, between ca. 40 and 200, and over 225-250 eggs. There were varietal differences in growth due to STCB. Watermelon varieties showed differences in stem lengths at egg levels above 150 eggs, while stem and root dry weight differences occurred above 225 and at 37-38 eggs, respectively.

Degree

Ph.D.

Advisors

York, Purdue University.

Subject Area

Entomology

COinS