Biology, Distribution, and Host Range of Zygina sp. (Hemiptera: Cicadellidae), a Potential Biological Control Agent for Asparagus asparagoides

Surveys in South Africa for potential biological control agents for Asparagus asparagoides, an environmental weed in Australia, revealed the presence of an undescribed leafhopper (Cicadellidae: Typhlocibinae: Zygina sp.). This paper examines the biology, distribution, and host specificity of Zygina sp. to ascertain its potential as a control agent. Eggs are deposited beneath the epidermis of mature phylloclades and nymphs feed predominantly on the underside of phylloclades. Zygina sp. has five nymphal instars which require means of 37.5 ± 0.5, 20.6 ± 0.2, and 12.2 ± 0.2 days to develop to adults at 15, 20, and 30°C, respectively. Nymphs and adults caused extensive damage to phylloclades at these temperatures. Adults survive more than 150 days on A. asparagoides plants but less than 5 days if given only water. Natural enemies include strepsipterans, mites, and mymarid egg parasitoids. Host-specificity testing in the laboratory and data from field surveys revealed that Zygina sp. feeds on closely related species, especially within the Asparagaceae, although eggs are laid on only a few species which, with A. asparagoides, were previously included in the genus Myrsiphyllum. Zygina sp. occurs throughout the range of its preferred hosts in South Africa, inhabiting winter-, even-, and summer-rainfall areas. The results indicate that Zygina sp. has potential as a control agent for A. asparagoides in Australia.