DIVERSIFICATION AND SECONDARY INTERGRADATION OF TWO CHRYSOPA CARNEA STRAINS (NEUROPTERA: CHRYSOPIDAE)

Abstract

Analysis of larval and adult characters, as well as biological data from various geographic populations, indicates that Chrysopa mohave Banks and Chrysopa carnea Stephens represent two strains of a single species and C. mohave is therefore designated a new synonym of C. carnea. The carnea strain occurs allopatrically throughout eastern and midwestern North America and the mohave strain is probably indigenous to California.The pattern of variation found in larvae and adults from different populations suggests that the carnea strain was secondarily introduced into California where it interbred with the mohave strain. This hybridization resulted in genetically varied populations with predominantly carnea characteristics in California’s Central Valley. Populations of the mohave strain occur in the California foothill and coastal areas because adults of the mohave strain, unlike the carnea strain, can aestivate during the hot, dry summers when food is sparse. Summer irrigation increases the abundance of larval and adult food which the non-aestivating carnea strain needs. It appears that the native mohave strain will compete successfully only in those areas of California which are unmodified by agricultural practices.