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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Insect Behavior and Biocontrol Research » Research » Publications at this Location » Publication #202356

Title: Competitive exclusion of a worldwide invasive pest by a native. Quantifying competition between two phytophagous insects on two host plant species

Author
item PAINI, DEAN - UNIVERSITY OF FLORIDA
item FUNDERBURK, JOE - UNIVERSITY OF FLORIDA
item Reitz, Stuart

Submitted to: Journal of Animal Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2007
Publication Date: 10/27/2007
Citation: Paini, D.R., Funderburk, J.E., Reitz, S.R. 2008. Competitive exclusion of a worldwide invasive pest by a native. Quantifying competition between two phytophagous insects on two host plant species. Journal of Animal Ecology. 77:184-190. DOI: 10.1111/J.1365-2656.2007.01324X.

Interpretive Summary: The western flowers thrips is a highly invasive pest that has spread throughout the world over the past 30 years. Although it has invaded the eastern USA, it has not become as abundant as in other geographic areas that it has invaded. Scientists with the Center for Medical, Agricultural and Veterinary Entomology and the University of Florida have been seeking to understand what factors affect the distribution and abundance of the western flower thrips. They have found that the eastern flower thrips, a closely related species, is competitively superior to the western flower thrips. The greater competitive ability of the eastern flower thrips may be a limiting factor for the distribution and abundance of the western flower thrips. Although the eastern flower thrips can damage crops, it is not a vector of plant viruses as is the western flower thrips. Therefore, this less pestiferous species may help limit damage from the western flower thrips in the eastern USA.

Technical Abstract: 1. High competitive ability is believed to be an important characteristic of invasive species. Many animal studies have compared the competitive ability of invasive species with a native species that is being displaced, but few have looked at systems where an invasive species has failed to establish itself. These types of studies are important to determine if competition is relevant not only to invading species but also to the biotic resistance of a community. 2. The thrips species F. occidentalis is a highly invasive crop pest that has spread from its original range (the western states of the US) to a worldwide distribution. Despite this, F. occidentalis is largely absent or occurs in low numbers in the eastern states of the US, where the native F. tritici dominates. It is possible that F. tritici is competitively excluding F. occidentalis from this region. 3. Larval competition between these two thrips species was tested on two known plant hosts, Capsicum annuum (a crop plant), and Raphanus raphanistrum (an invasive weed), using a response surface design with larval survival as the response variable. A response surface design allows a competition model to be fit to data using maximum likelihood estimation, thus generating a quantitative value for competition. 4. On both plant hosts, the native F. tritici did not experience significant competition from the invasive F. occidentalis, while F. occidentalis did experience significant competition from F. tritici. Competition from F. tritici larvae on F. occidentalis larvae was estimated to be 1.72 times (on C. annuum) and 1.76 times (on R. raphanistrum) the effect of intraspecific competition. The highly invasive F. occidentalis appears to be competitively excluded by the native F. tritici. 5. This study confirms the importance of competition in the biotic resistance of a community and is one of the few animal studies to not only test for competition in an apparently resistant ecosystem but also to quantify the level of interspecific competition between two animal species.