Role of Dalbulus maidis (Hemiptera: Cicadellidae) gender on maizebushy stunt phytoplasma transmission

There is a behavioral difference between male and female of insect vectors of plant pathogens that may reflect on the transmission of such pathogens. Dalbulus maidis is the leafhopper vector of the maize bushy stunt (MBS) phytoplasma. In this work, sex ratio of D. maidis collected directly from the maize whorl or with yellow sticky cards in a field plot in Piracicaba, SP (Brazil) was evaluated during the first month of the crop development. The natural MBS infection of the captured leafhoppers was assessed by PCR and the disease incidence was visually evaluated in the maize plots. Female D. maidis were more easily captured from the maize whorl, whereas male leafhoppers were more abundant in the cards. The incidence of MBS diseased plants in the plot was 21.2%. MBS phytoplasma was detected in 8% of the captured females whilst 2% of males carried the prokaryote. It is possible that the infected leafhoppers in the early stage of the crop contribute to the final disease incidence. Additionally, the acquisition and transmission rates to maize seedlings by males and females of D. maidis, virgin or mated, was studied. Acquisition rate of MBS phytoplasma was not significantly different between male and female leaf hoppers, however, female, either virgin or mated, transmitted the phytoplasma in a higher rate than males. The behavior of females of spending more time on the plant feeding may explain the higher natural infection of MBS phytoplasma in field condition and the increased transmission rate observed in the experiment.