Scanning electron microscope (SEM) micrographs of aedeagi and pygofer processes of some Cicadulina spp. are presented for the first time. They should assist in the identification of Cicadulina spp. by entomologists who are not trained in taxonomy, and who work in national research programmes in Africa without access to well-equipped libraries and reprint collections, that offer ready access to the original descriptions of Cicadulina spp. A number of national maize research programmes recently initiated studies on Cicadulina leafhopper biology, behaviour, ecology and mass rearing for resistance screening to streak virus and all of them face the problem of species identification. This report summarizes widely scattered publications and provides new illustrative information to assist in the identification of Cicadulina spp. by national scientists in Africa.

Regular field surveys were carried out in 2 week intervals in 1986 and 1987 to determine population density, species composition, migration activity of Cicadulina leafhoppers and their infectivity with maize streak virus (MSV) in different ecological locations of southeastern Nigeria: mangrove swamp forest (IITA and RIART station at Onne), deltaic swamp forest (RSUST, Port Harcourt), seasonal swamp forest (Iriebe) and high forest zone (NCRI, Amakama near Umuahia).

Population density was always low during dry season, significantly lower in the rain forest zone and higher in the swamp forest, rapidly rising in the second rainy season in all ecological zones and reaching its maximum before the rains finally stopped. Sharp increase in the population density in Nov. and Dec. may indicate mass migration activity of Cicadulina leafhoppers from already dry areas of adjacent Guinea savanna at that period.

Six species of Cicadulina were collected from most of sampled areas. C. ghaurii was the predominant species in 1986 and 1987, averaging 55.9% for all locations and periods. Its portion was higher in the mangrove swamp forest (Onne) than in the high forest zone (Amakama). The predominance of other species declined in the order: C. triangula (18.2%), C. mbila (17.2%), C. arachidis (5.9%), C. similis (2.8%) and C. hartmansi (0.1%). In absolute values, the portion of individuals out of the total number of leafhoppers collected was for C. triangula 53.7%, C. ghaurii 25.5%, C. mbila 17.3%, C. arachidis 2.3%, C. similis 1.1% and C. hartmansi0.1%. A high population of C. triangula occurred only in the relatively short period in Nov.-Dec, especially in Iriebe and was correlated with the rapid increase of Cicadulina densities in all sampled areas; a high migration activity of C. triangula and C. mbila was confirmed.

Incidence of MSV in the surveyed farmers' field varied between 0–22% in the first rainy season (1987) and 12–25% in the second rainy season (1986). The portion of Cicadulina adults already infected with MSV under field conditions and capable of transmitting MSV to the susceptible maize seedlings varied from 3.3 to 23.3%, with higher values for leafhoppers collected at the end of the second rainy season.

Available pieces of information on Cicadulina sp. leafhopper biology, with specific references to the suitability of various species for mass rearing and resistance screening for maize streak virus (MSV) are critically reviewed. The following are summarized: (a) effect of distribution pattern and species composition on the efficiency of collection of live specimens for establishing a colony for mass rearing; (b) species biology and fecundity as affected by temperature and humidity; (c) species specificity in MSV transmission; (d) host plant preference and adaptation to mass rearing conditions. All these parameters affect the suitability of various Cicadulina species used as vectors in maize resistance screening and breeding to MSV disease.