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

DEFEA BÁRBARA; RUSCONI MATÍAS; DELLAPÉ GIMENA; ACHINELLY , MARÍA F.

Mendoza

Congreso; X Congreso Argentino de Entomología.; 2018

Sociedad argentina de entomología

Mermithids are obligate parasites of invertebrates. Insects are commonly reported as hosts ofthese nematodes, however, they can also be found in other groups such as crustaceans, spiders,scorpions, pseudoscorpions and molluscs, among others. Within the Hexapoda, most orders,including Collembola, Siphonaptera and Hemiptera, have been recorded as hosts for mermithids, butaccording to Poinar (1975), those nematodes found in Hemiptera are probably accidental infections.Actually, the records of mermithid parasitism of Auchenorrhyncha are from USA and Ireland, not inSouth America. During a survey for a diversity study parasitic nematodes of the family Mermithidaewere found within specimens of leafhoppers (Auchenorrhyncha: Cicadellidae). Sampling was carriedout at the EEA, INTA Bella Vista located in Corrientes province during 2013-2015. Insect hosts werecollected from weeds around a Citrus sinensis (L.) Osb. orchard using an entomological sweep net.The collected specimens were preserved in tubes with 70% ethanol. Host species were identifiedbased on Young (1977). Adults and nymphs of the sharpshooter species Hortensia similis (Hemiptera:Cicadellidae: Cicadellinae) were detected to carry mermithid nematodes. All nematodes hadpartially emerged from the host and in some nymphs they emerged from the dorsal side. Of the 2133specimens of H. similis only 7 (6 nymphs, 1 adult) presented parasitism. This low rate of parasitism(0.33%) agrees with previous works from USA and Ireland which found a parasitism rate of only0.3% from 60.000 Auchenorrhyncha specimens. We believe that the vegetation physiognomy, alongwith the climatic and soil conditions (e.g. heavy rains, deluge) of the sampling site contribute to thisfortuitous 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.For this reason, molecular identification is being carried out. The parasitized specimens alongwith the mermithids will be deposited in the Entomological Collection of the Museo de La Plata(MLP), Argentina. In this work, we found the first extant example of mermithid infection ofAuchenorrhyncha in South America.