Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2002
Publication Date: 10/20/2002
Interpretive Summary: Undesirable native plants such as snakeweed, tarbush, creosote bush or mesquite are generally studied for management purposes in isolation from the rest of the plant community. Those studies tend to overlook the mechanisms underlying the system that could lead to its successful management. This study presents a systemic approach to identifying insect plant utilization patterns and describes the structure of a leafhopper guild from a Chihuahuan desert plant community. More than 35 leafhopper species on 13 woody and perennial plants were studied. Individual plants were sampled with sticky-traps on 9 dates. Numbers of leafhoppers and plant volume of each plant were recorded. Leafhoppers utilized the plant species in different proportions to plant occurrence. About 40% of all possible plant-insect pairs occurred less often than expected or did not occur and 9.5% of the pairs occurred more often than expected. The remaining 50% occurred in proportion to plant availability. The host plant patterns gathered in this study exhibited 85% similarity with published host records. The utilization of this methodology is discussed to identify agents for augmentative biological control.
Technical Abstract: We examined plant use versus plant availability by a leafhopper guild from a Chihuahuan Desert plant community. Some native woody plants species of the Chihuahua Desert behave as weeds (e.g., Gutierrezia spp.) and could be subjects of augmentative biological control. As a first step, we wanted to know how the leafhopper guild used the woody plant community in the Chihuahua Desert to identify possible candidates to be studied. At least 37 leafhopper species were sampled on 13 woody and perennial plant species. Individual plants were sampled with sticky-traps on nine dates from June 1997 to July 1998. Leafhopper counts and plant availability were used to determine if leafhoppers used plants in proportion to their availability. Analysis of the 13 most abundant leafhopper species indicated differential use of at least one or more plant species in proportion to plant occurrence. Approximately 40% of all possible plant-insect pairs (169 pairs, 13 plants, and 13 insects) demonstrated under-utilization of plants (less than expected) by the leafhoppers. Nearly 50% of the pairs demonstrated plant use in proportion to their availability (random utilization), and in only 10% of pairs, leafhoppers used plants more often than expected. In our study site, 66.7% of the leafhopper species exhibited preference for one or two plant species, whereas the remaining 33.3 exhibited no preference for any studied plant. Our plant utilization results reaffirm published available host plant records for the leafhoppers analyzed. Qualitative temporal patterns in plant utilization were not detected. Specialist species exhibited different host uses in response to increasing leafhopper abundance. At seasonal peak abundance, specialist leafhoppers showed two different strategies: leafhoppers increased their preference toward their preferred host plants, and leafhoppers decreased their preference toward their preferred plants. The possible use of this methodology for augmentative biological control is discussed.