Aphids are a serious threat to agriculture, despite being a rather small group of insects. The about 4,000 species worldwide engage in highly interesting and complex relationships with their microbial fauna. One of the key symbionts in arthropods is Wolbachia, an α-Proteobacterium implicated in many important biological processes and believed to be a potential tool for biological control. Aphids were thought not to harbour Wolbachia; however, current data suggest that its presence in aphids has been missed, probably due to the low titre of the infection and/or to the high divergence of the Wolbachia strains of aphids. The goal of the present study is to map the Wolbachia infection status of natural aphids populations, along with the characterization of the detected Wolbachia strains. Out of 425 samples from Spain, Portugal, Greece, Israel and Iran, 37 were found to be infected. Our results, based mainly on 16S rRNA gene sequencing, indicate the presence of two new Wolbachia supergroups prevailing in aphids, along with some strains belonging either to supergroup B or to supergroup A.

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The aphid-transmitted Moroccan watermelon mosaic virus (MWMV; Potyvirus, Potyviridae) is an emerging pathogen in cucurbit crops in the Mediterranean basin but information on its transmitting vector species is limited. This study aimed to record the competence of 22 species of the Greek aphid fauna to vector MWMV. Timed-probe transmission experiments and arena tests were performed using laboratory colonies of aphid species abundant in field surveys; less common species were tested as apterous individuals collected directly from field plants in mass-inoculation (nonpersistent) tests. Depending on the test, aphids were tested in cohorts of 10 or 20 individuals on zucchini (Cucurbita pepo L.) plants and the frequency of transmission was calculated for a single aphid. Among 12 species tested in timed-probe transmission tests, Myzus persicae nicotianae (74.0%) appeared to be the most efficient vector, followed by M. persicae (48.0%), Aphis gossypii (11.8%), an unidentified Aphis sp. (11.8%), and A. spiraecola (11.0%). Alatae of nine species tested in arena tests transmitted the virus in rates varying from 0.7 to 53.6%; M. persicae was the most efficient species in virus spread. In mass-inoculation tests, the probability that apterae of 12 aphid species collected from field plants transmitted MWMV fluctuated from 0.3 to 5.3%. No transmission was obtained by Brevicoryne brassicae. The following species are reported as new vectors of MWMV: A. fabae, A. nerii, A. spiraephaga, A. umbrella, Capitophorus eleaegni, Dysaphis (Pomaphis) pyri, Macrosiphoniella sanborni, Macrosiphum rosae, Myzocallis castanicola, Myzus persicae nicotianae, M. cerasi, M. varians, Phorodon humuli, Ovatus crataegarius, Takecallis arundicolens (first report in Greece), Uroleucon sonchi, and U. (Uromelan) aeneum. These results contribute to a better understanding of MWMV epidemiology.

In this paper we report two aphid species as new records for the Greek and the European aphid fauna. The species are Aphis odinae (van der Goot) and Melanaphis sorghi (Theobald) (Hemiptera: Aphididae). The former was found on Pittosporum spp. in Thessaloniki, northern Greece, and the latter on Sorghum halepense (L.) in Messolonghi, southern Greece, and also in Thessaloniki. Heavy infestations in Pittosporum trees by A. odinae have not been observed and M. sorghi was not detected in cultivated sorghum or maize in the few inspections we made. Thus, according to our inspections neither of these species is as yet of economic importance in Greece. These two species increase the number of aphid species recorded in Greece to 335.

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