Epidemiology of Plasmodium hexamerium Huff, 1935, in meadowlarks and starlings of the Cheyenne Bottoms, Barton County, Kansas.

A 2-year epidemiological study of Plasmodium hexamerium in meadowlarks and starlings of the Cheyenne Bottoms Waterfowl Management Area, Barton County, Kansas, revealed that seasonal infection incidence varied significantly in the meadowlark, being highest in the early spring and lowest in the winter, but did not vary significantly in the starling. Both host species became infected at an early age, the meadowlark in the nest and the starling soon after leaving it. In concurrent vector studies: (1) Culex tarsalis was infected with P. hexamerium in the laboratory; (2) C. tarsalis, Aedes nigromaculis, and A. sollicitans were exceedingly abundant and fed regularly on small birds in the field, therefore all are considered potential vectors with C. tarsalis the most likely; (3) mosquito populations were not high until June when annual transmission probably begins; (4) populations of probable vectors are too low during March and April to account for the observed increase in malaria incidence in meadowlarks collected at that time. Overall differences in the epidemiological patterns of P. hexamerium in the meadowlark and starling are credited principally to differences in migratory habitats of the two birds and degree of ecological association with vectors. The natural transmission of avian malaria is one of the most poorly understood aspects of the biology of Plasmodium. Herman's (1938) study of malaria in the redwing (Agelaius phoeniceus (L.)) is a classic and has been supplemented only recently by the work of Fallis and others on Leucocytozoon (Fallis, Anderson, and Bennett, 1956; Fallis and Bennett, 1963; Fallis, Davies, and Vickers, 1951; Fallis, Pearson, and Bennett, 1954). Growing interest in the ecology of the encephalitis viruses, along with the suggestion that bird malaria studies may shed light on this problem (Herman et al., 1954), makes further work on the epidemiology of avian malaria desirable. The present survey was part of a general study of animal parasites and viruses in central Kansas which began in February 1963 and is still in progress. The meadowlarks (Sturnella magna (L.) and S. neglecta Aud.) and European starling (Sturnus vulgaris L.) were studied because both were found to harbor Plasmodium hexamerium Huff. Thus, variations in epidemioReceived for publication 15 October 1965. * Taken from a dissertation submitted to Graduate College in partial fulfillment of requirements for degree of Doctor of Philosophy. Supported in part by NIH Grant AI-05232-02 which provided many of the facilities used. t Present address: Department of Zoology, Rutgers University, New Brunswick, New Jersey. logical patterns of this parasite in its different hosts might be manifestations of factors which generally affect avian malaria epidemiology.