PW12 Pesticide II
Exhibit Hall
8:00 AM - Wednesday
(PW210) Pesticide effects on kin selection in amphibians.
Rappi, G.1, Brown Sullivan, K.1, 1 Department of Biological Sciences, Wichita State University, Wichita, KS, USA
ABSTRACT- Declines in amphibian abundance have been attributed to pathogens, acidification, UV radiation, habitat loss/alteration, introduced species and agricultural/industrial chemicals. Responses typically measured include lethality, disruption in developmental progress and growth during larval stages, and alteration of sexual differentiation. Recently, experiments to identify potential causes for amphibian declines have included effects on behavior. For example, carbaryl and atrazine have been reported to alter activity levels and/or anti-predator responses of tadpoles. Kin selection is proposed to facilitate group aggregation among tadpoles and mate selection in adults. Disruption of kin preferences may increase the probability of tadpole predation and alter genetic population structure via changes in mate selection. No studies have investigated the potential impact of pesticides on kin selection. This study was designed to examine the effects of exposure to the herbicide atrazine and the organophosphate insecticide chlorpyrifos on kin selection of Bufo woodhousei and Xenopus laevis, species in which tadpoles have been reported to exhibit a preference for aggregation near kin. For each species, 20 tadpoles were exposed to each of three atrazine (0, 20 and 200 
g/L) and three chlorpyrifos (0, 1 and 10 g/L) treatments during a two week interval following hatching. Tadpoles were then observed individually for 10 minutes in tanks containing full-siblings in one end compartment and non-siblings in the other end. The total activity and time spend in each end were recorded. Perforated plexiglass compartments allowed movement of water between the test organism and cue animals. Preliminary results for atrazine indicate decreased levels of activity with an increase in exposure. Proportional time spend in the third of the tank area near kin and near non-kin will be compared among pesticide treatments to assess the potential impact of these chemicals on tadpole preference for aggregation near related individuals.
Key words: kin selection, amphibian, pesticides