Eriophyid Mites in Classical Biological Control of Weeds: Progress and Challenges

A classical biological control agent is an exotic host-specific natural enemy, which is intentionally introduced to obtain long-term control of an alien invasive species. Among the arthropods considered for this role, eriophyid mites are likely to possess the main attributes required: host specificity, efficacy, and long-lasting effects. However, so far, only a few species have been approved for release. Due to their microscopic size and the general lack of knowledge regarding their biology and behavior, working with eriophyids is particularly challenging. Furthermore, mites disperse in wind, and little is known about biotic and abiotic constraints to their population growth. All these aspects pose challenges that, if not properly dealt with, can make it particularly difficult to evaluate eriophyids as prospective biological control agents and jeopardize the general success of control programs. We identified some of the critical aspects of working with eriophyids in classical biological control of weeds and focused on how they have been or may be addressed. In particular, we analyzed the importance of accurate mite identification, the difficulties faced in the evaluation of their host specificity, risk assessment of nontarget species, their impact on the weed, and the final steps of mite release and post-release monitoring.

Description of Cecidophyes fibigiae n. sp., new combinations, records, and DNA barcodes of eriophyid mites (Eriophyoidea, Eriophyidae) from Karadag Nature Reserve (Crimea)

We report on one new cecidophyine species, Cecidophyes fibigiae n. sp. from Fibigia clypeata (L.) Medik. (Brassicaceae) and three new combinations and seven new records of phyllocoptine mites in Crimea: Abacarus hystrix (Nalepa 1896) from Elytrigia elongata (Host) Nevski (Poaceae), Aculodes cf holcusi Skoracka 2004 from Aegilops biuncialis Vis. (Poaceae), Aculops coronillae (Canestrini & Massalongo, 1893) n. comb. from Securigera varia (L.) Lassen (Fabaceae), Aculops longifilis (Canestrini 1891) n. comb. from Onobrychis miniata (Kit.) DC. (Fabaceae), Aculus sp. from Galium humifusum M.Bieb. (Rubiaceae), Anthocoptes recki (Bagdasarian, 1972) from Pistacia atlantica subsp. mutica (Fisch. & C.A. Mey.) (Anacardiaceae), and Anthocoptes thymi (Nalepa) n. comb. from Thymus callieri Borb. ex Velen. (Lamiaceae). Partial mitochondrial Cox1 sequences (about 1150 bp) of all found species were obtained (GB accession numbers MW439274–MW439282).

A new species of Typhlodromus (Anthoseius) De Leon and redescription of T. (A.) montanus Chant & Yoshida-Shaul from Russia

Typhlodromus (Anthoseius) tetraporus sp. nov., collected on grasses in Crimea, is proposed as a new species for science. The new species can be separated from all known species of Typhlodromus (Anthoseius) by the combination of following characters; peritreme extending almost to level of setae j1, four pairs of solenostomes on dorsal shield, two pairs of setae on sternal shield, a sclerotised v-shaped plate posterior to sternal shield, four pairs of pre-anal setae, a pair of small rounded pre-anal solenostomes, differentiated and larger atrium of spermatheca and eight setae on genu II. In addition, T. (A.) montanus Chant & Yoshida-Shaul (Acari: Phytoseiidae), a species only known based on its original description from Canada is reported for the first time in Russia. The new record is redescribed and illustrated based on female specimens collected from Prunus padus L. (Rosaceae) where it was associated with eriophyid mites in Pereval Seminskiy, Altai Republic. This species may be an important predator as a potential biological control agent of eriophyid mites.

PHYLOGENETIC ANALYSIS OF UKRAINIAN ISOLATE OF RASPBERRY LEAF BLOTCH VIRUS

Raspberry leaf blotch virus (RLBV) is a new member of the Emaravirus genus (Fimoviridae, Bunyavirales). Representatives of this family are characterized by a segmented "-" RNA genome, helical nucleocapsid and enveloped spherical or pleomorphic virions 80-120nm in diameter. Transmission of these viruses is carried out by eriophyid mites. The virus is widely distributed in Europe. In this paper, the phylogenetic relationships between the Ukrainian RLBV isolate and isolates from the other countries from the GenBank database were investigated. Samples of symptomatic raspberry plants were selected for the work. Total RNA was isolated and RT-PCR was performed using primers to the region of the nucleocapsid protein (P3) gene. The resulting amplicon with a length of about 500bp was sequenced. Sequences were analyzed using BLAST and MEGA7 programs. As a result of BLAST analysis, it was shown that the Ukrainian isolate of RLBV has a high similarity to some Finnish, British, Serbian and Slovak isolates (93-99% similarity). Nevertheless, the dendrogram constructed in MEGA7 did not distribute these isolates in a separate cluster. Interestingly, sequences of isolates from Finland, Britain, and the Balkans were segregated into different parts of the phylogenetic tree. This pattern can be explained by the low divergence of the virus population or small number of isolates in the database.

Description of a new eriophyid species from Hungary (Acari: Acariformes: Eriophyidae)

A new species of eriophyid mites, Aceria bassicola sp. n. (Acari: Acariformes: Eriophyoidea: Eriophyidae), collected from Bassia prostrata (L.) Beck (Amaranthaceae), is described from Hungary based on females, males and nymphs.

Seven new vagrant eriophyoid species (Acari: Eriophyoidea) from semi-arid and arid environment in East Iran

During field surveys of eriophyid mites associated with autochthonous plants species in semi-arid and arid environments in East Iran (Birjand, South Khorasan, Iran, summer 2016 and 2017), seven new eriophyid mite species (Acari: Eriophyidae) were discovered. They are Aceria astratorae sp. nov. on Astragalus pinetorum Boiss. (Leguminosae), Aceria astracanthae sp. nov. on Astracantha echidna (Bunge) Podlech (Leguminosae), Aceria furgae sp. nov. on Ephedra major Host (Ephedraceae), Aceria runicae sp. nov. on Rubia caramanica Bornm. (Rubiaceae), Aculus birsutum sp. nov. on Epilobium hirsutum L. (Onagraceae), Phyllocoptes birreae sp. nov. on Centaurea virgata Lam. (Compositae), and Neophytoptus semenovis sp. nov. on Semenovia suffruticosa (Freyn & Bornm.) Manden (Apiaceae), which are illustrated and described herein. All seven new species appear to be vagrants on green parts of their host plants with no particular symptom.

A Survey of Rose rosette virus and Eriophyid Mites Associated with Roses in the Southeastern United States

The eriophyid mite, Phyllocoptes fructiphilus, vectors the causal agent, Rose rosette virus (RRV), that results in rose rosette disease. Parts of the southeastern United States have remained free of the disease, except for infected plant material introductions that were eradicated. A survey of sampling points through Alabama, Georgia, and Mississippi (n = 204) revealed the southeastern border of RRV. The presence of RRV in symptomatic plant tissue samples (n = 39) was confirmed by TaqMan-quantitative reverse transcription polymerase chain reaction (RT-qPCR). Samples were also collected at every plot for detection of eriophyid mites, specifically for P. fructiphilus. Three different species of eriophyid mites were found to be generally distributed throughout Alabama, Georgia, and Mississippi. Most of these sites (n = 60) contained P. fructiphilus, found further south than previously thought, but in low populations (<10 mites/gram of tissue) south of the RRV line of incidence. Latitude was found to be significantly correlated with the probability of detecting RRV-positive plants, but plant hardiness zones were not. Plot factors such as plant size, wind barriers, and sun exposure were found to have no effect on P. fructiphilus or the presence of RRV. The reason for the absence of RRV and low populations of P. fructiphilus in this southeast region of the United States are unclear.