Hybridization studies in the Schistocerca americana complex. I. The specific status of the Central American Locust

Abstract

The Central American Locust has previously been identified as Schistocerca paranensis (Burmeister), the Argentinian Locust, and it has been suggested that S. americana of North America represents its solitarious phase. Hybrids of locusts from the Yucatan peninsula of Mexico with locusts from Argentina and Florida were reared, their fertility measured and meiosis in the males examined. It was found that: (1) sex ratios in the F, hybrids were distorted; (2) hybrids had reduced fertility; (3) female hybrids were more fertile than male hybrids; (4) meiosis in hybrid males was disturbed; (5) these effects were more pronounced in die hybrids with the Argentinian Locust than in those with Florida locusts. These results are discussed in relation to Haldane's rule and the biogeography of die group. It is concluded that the Central American and Argentinian Locusts are separate species, but that the relationship of the former to S. americana americana requires further investigation.