Identification of Plant DNA in Adults of the Phytoplasma Vector Cacopsylla picta Helps Understanding Its Feeding Behavior

Apple proliferation is an economically important disease and a threat for commercial apple cultivation. The causative pathogen, the bacterium ‘Candidatus Phytoplasma mali’, is mainly transmitted by Cacopsylla picta, a phloem-feeding insect that develops on the apple tree (Malus spp.). To investigate the feeding behavior of adults of the phytoplasma vector Cacopsylla picta in more detail, we used deep sequencing technology to identify plant-specific DNA ingested by the insect. Adult psyllids were collected in different apple orchards in the Trentino-South Tyrol region of northern Italy. DNA from the whole body of the insect was extracted and analyzed for the presence of plant DNA by performing PCR with two plant-specific primers that target the chloroplast regions trnH-psbA and rbcLa. DNA from 23 plant genera (trnH) and four plant families (rbcLa) of woody and herbaceous plant taxa was detected. Up to six and three plant genera and families, respectively, could be determined in single specimens. The results of this study contribute to a better understanding of the feeding behavior of adult Cacopsylla picta.

Biological characterization of Euscelidius variegatus iflavirus 1

Virus-based biocontrol technologies represent sustainable alternatives to pesticides and insecticides. Phytoplasmas are prokaryotic plant pathogens causing severe losses to crops worldwide. Novel approaches are needed since insecticides against their insect vectors and rogueing of infected plants are the only available strategies to counteract phytoplasma diseases. A new iflavirus, named EVV-1, has been described in the leafhopper phytoplasma vector Euscelidius variegatus, raising the potential to use virus-based application strategies against phytoplasma disease. Here transmission routes of EVV-1 are characterized, and localization within the host reveals the mechanism of insect tolerance to virus infection. Both vertical and horizontal transmission of EVV-1 occur and vertical transmission was more efficient. The virus is systemic and occurs in all life-stages, with the highest loads measured in ovaries and first to third instar nymphs. The basic knowledge gained here on the biology of the virus is crucial for possible future application of iflaviruses as biocontrol agents.

Occurrence of Scaphoideus titanus Ball and some other Auchenorrhyncha in the vineyards of western Slovakia

A study of Auchenorrhyncha was carried out in 2014 and 2015 in 7 vineyard plots with different varieties and pest management strategies in the Nitra wine region and Lesser Carpathian wine region in western Slovakia. The aim of this study was to obtain information related to the presence of potential vector insects associated with grapevine yellows phytoplasmas from the Flavescence dorée and Bois noir groups. Insects were collected by sweeping with an entomological net. Thirty species of Auchenorrhyncha were identified as belonging to 6 families. Cicadellidae were the most abundant, comprising 20 species. Scaphoideus titanus was collected at 4 localities. Identification of the phytoplasma vector is critical to the national strategy for assessment and control of vectors spreading the phytoplasma disease in Slovakian vineyards. The first finding of Metcalfa pruinosa was noticed in vineyards in Slovakia.

A New Disease in Limonium latifolium Hybrids. II. Investigating Insect Vectors

Symptoms typical of a phytoplasma infection were observed on a large number of Limonium hybrids in Israel in October 2000. Phytoplasma infection was confirmed by electron microscopy and polymerase chain reaction analysis. To identify the agent of pathogen spread surveys were made of candidate leafhoppers vectors in Limonium hybrid crops: one known phytoplasma vector (Orosius orientalis (Matsumura)) was present in very large numbers, ≈10-fold greater than any other species; three other known vectors were present in low to moderate numbers (Circulifer haematoceps complex (Mulsant et Rey), C. tenellus complex (Baker) and Exitianus capicola Stål); individual specimens of other vectors were occasionally found. Field collected specimens of these four species were shown to vector phytoplasma to healthy Limonium hybrid seedlings; this is the first time E. capicola has been shown to be a phytoplasma vector. A laboratory colony of O. orientalis was additionally shown to be able to acquire the phytoplasma from infected Limonium hybrids and subsequently vector it to healthy seedlings.

Survey of palm-associated Fulgoroidea in Puerto Rico

We report results from a survey of palm-associated Fulgoroidea (planthoppers), following the recent discoveries of Haplaxius crudus, a known palm phytoplasma vector, and of other potential planthopper vectors in Puerto Rico. The survey, which sampled from 40 sites, resulted In the identification of 30 morpho-species belonging to eight Fulgoroidea families. The 10 most common species accounted for 93.9% of individuals, whereas near one third (n = 9) of the species were represented by single individuals. Derbids and cixiids accounted for 90% of collected individuals. The most common species were the derbids Cedusa inflata (Ball) and Omolicna puertana Caldwell, while the most common cixiids were Bothriocera undata (F.) and Oliarus complectus Ball; and the most common flatids were Petrusa epilepsis (Kirkaldy) and Melornemis antillarum (Kirkaldy). Three species are new records for Puerto Rico: the cixiids Haplaxius crudus Van Duzee and Nymphomyndus caribbaea (Fennah), and the derbid Neocenchrea ca. pallida Metcalf. Impact of polyphagy and of abundance-diversity patterns of this planthopper guild on phytoplasma epidemiology are briefly discussed.