Zoophthora radicans affecting Zyginidia pullula

Mortality of the maize leafhopper Zyginidia pullula (Boheman) (Hemiptera Cicadellidae) had been observed on maize plants cultivated in northwest Italy since the ‘80s of last century. In past research several fungi from the dead leafhoppers having a saprophytic or pathogenic activity were isolated, but only lately Zoophthora radicans (Brefeld) Batko (Zygomycota Entomophthorales) was recognized as the actual pathogen. A research was conducted in 2003 and 2004 to find out how these fungi infected the leafhopper by weekly collecting 30 adult leafhoppers on maize plants and rearing them individually in the laboratory, repeating an unpublished experiment carried out in 1988. Z. radicans was confirmed to be by far the most frequent entomopathogenic agent (8.2% of adult mortality in July-October). It appeared in summer and its presence increased throughout the season, reaching a peak in August (even around 50% of adult mortality). The infestation decreased gradually until the beginning of frosts in November. The unusual drought accompanied by high temperatures during the whole summer in 2003 delayed the peak, that occurred at the beginning of October. Furthermore leafhoppers were infected in the laboratory to check the development of Z. radicans, that could complete its life history within four days and a half at 23 °C.