Mermithids nematodes parasitizing leafhoppers (Hemiptera: Cicadellidae) in South America

DEFEA, BARBARA; ACHINELLY, FERNANDA; DELLAPÉ, GIMENA; RUSCONI, JOSÉ MATÍAS

Mendoza

Congreso; X Congreso Argentino de Entomología; 2018

Sociedad argentina de entomología

Mermithids are obligate parasites of invertebrates. Insects are commonly reported as hosts of these nematodes, however, can also be found in other groups such as spiders crustaceans, scorpions, pseudoscorpions and molluscs, among others. Within the Hexapoda, most orders including Collembola, Siphonaptera and Hemiptera have been recorded as hosts for mermithids but according to Poinar (1975), those nematodes found in Hemiptera are probably accidental infections. Actually, the records of mermithid parasitism of Auchenorrhyncha are from the Neartic region in USA and Ireland, not in South America. During a survey for a diversity study parasitic nematodes of the family Mermithidae were found within specimens of leafhoppers (Auchenorrhyncha: Cicadellidae). Sampling was carried out at the EEA, INTA Bella Vista located in Corrientes province during 2013-2015. Insect hosts were collected from weeds around a Citrus sinensis (L.) Osb. orchard using an entomological sweep net. The collected specimens were preserved in tubes with 70% ethanol. Hosts species were identified based on Young (1977). Adults and nymphs of the sharpshooter species Hortensia similis (Hemiptera: Cicadellidae: Cicadellinae) were detected carrying mermithid nematodes. All nematodes had partially emerged from the host and in some nymphs they emerged from the dorsal side. Of the 2133 specimens of H. similis only 7 (6 nymphs, 1 adult) presented parasitism. This low rate of parasitism (0.33%) agreeing with previous works from USA and Ireland which found a parasitism rate of only 0.3% from 60.000 Auchenorryncha specimens. We believe that the vegetation physiognomy, along with the climatic and soil conditions (e.g. heavy rains, deluge) of the sampling site contribute to these fortuitous parasitism. The mermithids were preserved in the process of emerging from their hosts, which means that they were juveniles and not the adults needed for morphological identification so it has not been possible the morphological identification. For this reason, molecular identification is being carried out. The parasitized specimens along with the mermithids will be deposited in the Entomological Collection of Museo de La Plata (MLP), Argentina. In this work, we found the first extant example of mermithid infection of Auchenorrhyncha in South America.