Isolation, morpho-molecular identification, and pathogenicity evaluation of entomopathogenic fungi from the Pear psylla [Cacopsylla pyri L.)] in Turkey

Abstract The Pear psylla, Cacopsylla pyri L. (Hemiptera: Psyllidae), is the main pest of pears in all pear-growing regions of Turkey as well as in Antalya province (southwestern part of Turkey). Its control mainly relies on the use of synthetic chemical insecticides; however, in last decade, desired levels of control have not been achieved due to development of resistance to these insecticides. Previous studies have shown that entomopathogenic fungi (EPFs) may be a good alternative to pesticides to suppress pear psylla populations. Therefore, the objectives of this study were: (i) to isolate native EPFs from naturally infected individuals of pear psylla in Korkuteli county of Antalya province, (ii) to identify the collected EPF isolates, and (iii) to assess the effectiveness of these isolates against various developmental stages [eggs, young (1st and 2nd instars) and older (3rd and 5nd instars) nymphs, and adults of the pest under laboratory conditions. A total of 19 fungal isolates, including 12 Beauveria bassiana (Balsamo) Vuillemin (Deuteromycota: Hyphomycetes), 3 Penicillium raistrickii Smith, 2 P. chrysogenum Tom and 2 Aspergillus ochraceus Wilhelm (Ascomycota: Eurotiomycetes)] were recovered from 63 fungal-infected psyllid cadavers during a two-year survey. In initial screening tests, 9 B. bassiana isolates, producing ≥ 20% mortality in the nymphal (young or older) stages of C. pyri , were also confirmed by molecular identification and included in the virulence assays for further evaluation against the pest. All 9 isolates were tested at three different conidial concentrations (1 × 10 5 , 1 × 10 6 and 1 × 10 7 conidia/ml), using spray method. The results of virulence assays showed that all 9 B. bassiana isolates had low ovicidal and adulticidal activity (both egg and adult mortalities were below 20%) while they caused significant mortalities on young nymphs. Of the 9 B. bassiana isolates tested, two isolates (AKBBPN2 and AKBBPN6) were the most virulent, causing 94.2 and 92.7% mortalities, respectively, in young nymphs within 14 days at the highest concentration (1 × 10 7 conidia/ml). The findings of the current study indicated that these two B. bassiana isolates from C. pyri nymphal cadavers may provide an essential basis for the development of bioproducts, as well as a promising alternative method for controlling the pest.