Testing local isolates of entomopathogenic microorganisms against Brown Marmorated Stink Bug

The brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae) (BMSB) is an exotic invasive insect which has spread extensively and established in new area of Black sea regions of Georgia. During 2017-2019, infected adults with fungal disease symptoms were found in population of H. halys from different regions of Western Georgia. Three isolates of entomopathogenic fungus Beauveria bassiana sensu lato and one of Isaria cf fumosorosea were recovered. Mycoinsecticide Bover-Ge, based on a local strain of B. bassiana-024 (isolated from soil high mountain of Caucasus Range, provide molecular identification in CABI-UK, gave a unique cultural number - IMI # 501797 and keep in CABI Genetic Recourse Collection) two concentrations (1×107 and 1×108 conidia/ml) was tested on the adults of H. halys in laboratory and its efficiency reached 72.0-90.5%. Under laboratory conditions, local isolates of nematodes Heterorhabditis bacteriophora and Steinernema borjomiensis were tested on H. halys adults. At three increasing concentrations (200, 500 and 1000 IJs/mL), H. bacteriophora caused bug mortality at the rates of 33-47%. As for Steinernema borjomiensis, the respective values were 13-33%

Steinernema tbilisiensis sp. n. (Nematoda: Steinernematidae) - A New Species of Entomopathogenic Nematode from Georgia

A new species of entomopathogenic nematode (EPN), Steinernema tbilisiensis sp. n. is described. The species was isolated from soil samples of the deciduous forest located in the Tbilisi area. Morphological and morphometric data as well as phylogenetic analysis show that S. tbilisiensis sp. n. belongs to the group S. affine/intermedium. S. tbilisiensis sp. n. has been attributed to the group S. affine/intermedium on the basis of spicule and gubernaculum structure. The new species differs from other species of the S.affine/intermedium group in the following diagnostic characters: the spicule of S. tbilisiensis sp. n. is the smallest and the gubernaculum of S. tbilisiensis sp. n. is shorter than other species of the S. affine/intermedium group. Infective juveniles (IJs) of S. tbilisiensis sp. n. are distinguished by a relatively long body (L = 866 μm), the position of excretory pore (EP = 72 μm), the length of the esophagus (ES = 140 μm) and the length of the anal body width (ABW = 25 μm). IJs of S. tbilisiensis sp. n. have four lateral lines like S. beddingi, but the number of lines is six in S. affine, S. sichuanense and S. intermedium. Also the analysis of rDNA (28S and ITS) gene sequences depicts this Steinernema species as a distinct and unique entity

Steinernema borjomiense n. sp. (Rhabditida: Steinernematidae), a new entomopathogenic nematode from Georgia

A new species of entomopathogenic nematode, Steinernema borjomiense n. sp., was isolated from the body of the host insect, Oryctes nasicornis (Coleoptera: Scarabaeidae), in Georgia, in the territory of Borjomi-Kharagauli. Morphological characters indicate that the new species is closely related to species of the feltiae-group. The infective juveniles are characterised by the following morphological characters: Body length of 879 (777-989) μm, distance between the head and excretory pore = 72 (62-80) μm, pharynx length = 132 (122-142) μm, tail length = 70 (60-80) μm, ratio a = 26.3 (23.0-29.3), H% = 45 (40-51), D% = 54 (47-59), E% = 102 (95-115), and lateral fields consisting of seven ridges (eight incisures) at mid-body. Steinernema borjomiense n. sp. was molecularly characterised by sequencing three ribosomal regions (the ITS, the D2-D3 expansion domains and the 18S rRNA gene) and the mitochondrial COI gene. Phylogenetic analyses revealed that S. borjomiense n. sp. differs from all other known species of Steinernema and is a member of the monticolum-group

Potential of four entomopathogenic nematodes for the control of brown marmorated stink bug Halyomorpha halys

Abstract: The aim of our study was to established potential entomopathogenic nematodes (EPNs) and determine their effectiveness on the brown marmorated stink bug – Halyomorpha halys – for its control. In experimental trial four entomopathogenic nematodes were used: two of Georgian species Heterorhabditis bacteriophora (HRB, GEO) and Steinernema borjomiensis; two Italian species Heterorhabditis bacteriophora (HRB, IT) and Steinernema apuliae. In laboratory assay (22 °C and 80% RH), the mentioned nematodes were used in the following doses: 1:1000, 1:500, 1:200 infective juveniles (IJs) per adult of H. halys. The mortality of tested insects was estimated from the third day after treatment. Significant differences were observed between Georgia and Italian species. HRB (GEO) and S. borjomiensis at the high concentration of 1:1000, mortality achieved 46.6-33.3%, in case of 1:500 – 33.3-32% and in 1:200 – 33.3-13.3% were reached accordingly. More pathogenic were Italian species: HRB(IT) and S. apuliae in high concentration of 1:1000, where mortality was 93.3-53.3%, in case of 1:500 – 93.3-40% and in 1:200 – 73.3-33.2% were observed, respectively. The emerging IJs were harvested and counted throughout the interval of 11-15 days