Biological traits of Cosmocomoidea annulicornis (Hymenoptera: Mymaridae), an egg parasitoid of the sharpshooter Tapajosa rubromarginata (Hemiptera: Cicadellidae), a vector of Xylella fastidiosa in citrus orchards

Abstract

The parasitic ability of Cosmocomoidea annulicornis (Hymenoptera: Mymaridae) was tested on eggs of the sharpshooter Tapajosa rubromarginata (Hemiptera: Cicadellidae), vector of the bacterium Xylella fastidiosa that causes citrus variegated chlorosis (CVC), among other plant diseases. In the present study, we evaluated biological traits of C. annulicornis such as parasitism and emergence rates, developmental time, longevity and sex ratio in laboratory conditions on leaves of Citrus aurantium, C. limon, Zea mays and Sorghum halepense. In addition, the functional response of C. annulicornis on host egg masses laid on C. aurantium leaves was studied and new distribution sites of the parasitoid in Argentina are reported. The overall parasitism of C. annulicornis was 49.20 ± 2.90%. Of those parasitized eggs, 83.30 ± 6.51% adults emerged. Parasitism of C. annulicornis was significantly lower in host eggs laid on S. halepense and developmental time was longer in C. limon compared to the other host plant species tested. In all host plant species tested, females developed faster than males. Individuals lived on average 5.94 ± 0.23 days and statistically significant differences were found between the longevity of females and males. Sex ratio of parasitoids was balanced in all host plant species tested, excepted for maize plants, in which sex ratio was female biased. Cosmocomoidea annulicornis females exhibited a type III functional response, indicating a greater searching efficiency at high host densities compared to low densities. Previous reports of field parasitism in combination with our results of C. annulicornis performance on eggs of T. rubromarginata are indicators of a potential biological control agent against the vector of X. fastidiosa, though further studies are needed regarding its biology.