Tethered flight and morphometric studies with Cicadulina storeyi and C. mbila leafhoppers (Hemiptera: Cicadellidae) vectors of maize streak virus in Uganda

Abstract

Tethered flight studies, carried out in southern Uganda with the leafhoppers Cicadulina storeyi China and C. mbila Naude, showed that depending on species, the factors of age, gender, gravid status and rearing on virus infected maize had significant effects on flight, whereas host plant species and mated status appeared unimportant. Distributions of wing length (WL), body length (BL) and the parameters WL/BL and WL-BL were mostly uni-modal, but in two cases very weakly bi-modal. Regressions of log-transformed flight duration against these morphometric parameters were all non-significant, except for very weak (r 2 = 0.01-0.04) relations with wing length. There was no conclusive evidence for the existence of separate short-and long-duration flight morphs among the leafhoppers. It is proposed that differences between our results and those of an earlier study of Zimbabwean Cicadulina populations, particularly in respect of the effects of gravid status on flight, and the existence of distinct flight morphs, are explicable in terms of the different seasonal and environmental constraints experienced by Ugandan and Zimbabwean populations. These favour long-range migratory flight at certain times of the year in Zimbabwe, but not in Uganda.

The epidemiology, economic impact and control of maize streak disease

“…The two different types of leafhopper have subtly different body plans or "morphs" and it is possible that the "long distance flight morphs" are migratory forms that play a more important role in the epidemic spread of MSD Rose 1978). Migratory behavior is apparently absent in some leafhopper species but where it is present its characteristics vary from one population to the nextprobably due in part to both genetic differences between populations (Dabrowski et al 1991) and region-specific differences in environmental conditions (Downham and Cooter 1998;Rose 1972).…”