PARENT SESSION
Oral Session #78: Insect Population and Community Ecology. Presiding: R. Denno.
Friday, August 10, 2001. 8:00 AM to 11:45 AM. Hall of Ideas I.

Consequences of competitive ability for species abundance in a guild of phloem-feeding insects.

Ferrenberg, Scott¹, Denno, Robert¹, ¹

ABSTRACT- Interspecific competition between phytophagous insects has been questioned as a significant force influencing both population dynamics and community structure. We examined competitive interactions between two phloem-feeding species, the common Prokelisia dolus and the rare Delphacodes penedetecta (Hemiptera: Delphacidae). Both species are monophagous phloem-feeders on Spartina alternaflora in intertidal salt marshes of the mid-Atlantic. There were no interspecific effects of P. dolus on D. penedetecta. For D. penedetecta, however, there were strong adverse intraspecific effects on several fitness components. Intraspecific competitive effects were demonstrated in laboratory cultures and field cages. These results suggest that interspecific competition is not an important force dictating the abundance of D. penedetecta in the field. Rather, strong intraspecific competition and limited plant resources combine to influence the rarity of D. penedetecta.

KEY WORDS: Intraspecific competition, Interspecific competition, Bottom-up control, Species abundance