Leafhoppers and Cixiids in Phytoplasma-infected Carrot Fields: Species Composition and Potential Phytoplasma Vectors

Abstract

The first molecular analysis of samples collected in southern Bačka (Serbia) confirmed the presence of aster yellows (16SrI) and stolbur phytoplasmas (16SrXII) in insects belonging to the family Cicadellidae, as well as in carrot plants where the insects were collected. A correct identification of the phytoplasmas and their vectors is essential to arrange effective control strategies to prevent diseases associated with phytoplasmas from spreading to carrots and other vegetable crops. In order to enhance knowledge about insect vectors of aster yellows and stolbur phytoplasmas in Serbia, Cicadellidae and Cixiidae (Homoptera Auchenorrhyncha), the most common vectors of these phytoplasmas, were monitored in southern Bačka during 2008. Adults leaf- and planthoppers were collected and identified at species level using standard entomological methods, and tested for phytoplasma presence by means of PCR/RFLP. A total of 13 insect species of Cicadellidae were identified, as follows: a) three species of the subfamily Agallinae: Anaceratagallia ribauti (Ossiannilsson), Anaceratagallia venosa (Fourcroy), and Anaceratagallia laevis (Ribaut); b) seven species of the subfamily Deltocephalinae: Psammotettix confinis (Dahlbom), Psammotettix striatus (Linnaues) Psammottettix alienus (Dahlbom), Macrosteles sexnotatus (Fallén), Ophiola decumana (Kontkanen), Errastunus ocellaris Fallén, and Scaphoideus titanus Ball; c) three species of the subfamily Typhlocibinae: Eupteryx atropunctata (Goeze), Eupteryx mellissae Curtis, Zyginidia pullula (Boheman). Female specimens of the genus Euscelis (Deltocephalinae) were also collected, as well as one species of Reptalus quinquecostatus (Dufour) of the family Cixiidae. Stolbur phytoplasmas were detected in A. laevis, A. ribauti, A. venosa, P. striatus, P. confinis and P. alienus. The species: A. laevis, O. decumana, and P. confinis were AY-infected (subgroup 16SrI-A), while subgroup 16SrI-C was found only in one specimen of P. confinis. Since some aster yellows- and stolbur-infected species of the genera Psammotettix and Anaceratagallia (especially P. confinis and A. laevis) were regularly and commonly found in the infected carrot fields during the whole vegetative period, they could play a significant role in transmitting and spreading these pathogens in natural environment.

Prva molekularna istraživanja uzoraka iz južne Bačke potvrdila su prisustvo aster yellows (16SrI) i stolbur fitoplazmi (16SrXII) u insektima iz familija Cicadellidae, kao i u biljkama šargarepe među kojima su insekti sakupljani. Tačna identifikacija vrsta fitoplazmi i njihovih vektora su osnov za definisanje mera sprečavanja širenja fitoplazmoza u usevima šargarepe i drugog povrća. U cilju proširenja saznanja o insektima vektorima aster yellows i stolbur fitoplazmi, o kojima u Srbiji ima malo podataka, tokom 2008. godine nastavljeno je sa praćenjem insekata iz fam. Cicadellidae i fam. Cixiidae (kao najčešćih prenosilaca pomenutih vrsta fitoplazmi) u južnoj Bačkoj. Standardnim entomološkim postupcima sakupljana su imaga cikada, identifikovana do nivoa vrste i testirana na prisustvo fitoplazmi PCR/RFLP metodama. Identifikovano je ukupno 13 vrsta insekata iz familije Cicadellidae, od čega a) tri vrste iz subfamilije Agallinae: Anaceratagallia ribauti (Ossiannilsson), A. venosa (Fourcroy) i A. laevis; b) sedam vrsta iz subfamilije Deltocephalinae: Psammotettix confinis (Dahlbom), P. striatus (Linnaues), P. alienus (Dahlbom), Macrosteles sexnotatus (Fallén), Ophiola decumana (Kontkanen), Errastunus ocelaris Fallén i Scaphoideus titanus Ball; c) tri vrste iz subfamilije Typhlocibinae: Eupteryx atropunctata (Goeze), Eupteryx mellissae Curtis, Zyginidia pullula (Boheman). Prikupljen je i određen broj ženki iz roda Euscelis (Deltocephalinae), kao i jedna vrsta iz fam. Cixiidae Reptalus quinquecostatus (Dufour). Prisustvo stolbur fitoplazmi zabeleženo je u A. laevis, A. ribauti, A. venosa, P. striatus, P. confinis i P. alienus. Vrste A. laevis, O. decumana i P. confinis bile su inficirane AY (soj 16SrI-A), dok je soj 16SrI-C detektovan samo u jednoj jedinki P. confinis. S obzirom da su tokom čitavog vegetacionog perioda AY i STOL zaražene vrste iz rodova Psammotettix i Anaceratagallia (pre svega P. confinis i A. laevis) bile redovno i najčešće prisutne u zaraženim poljima šargarepe, one mogu imati značajnu ulogu u prenošenju i širenju ovih patogena u prirodi.