Phytoptus avellanae Nalepa (Acari: Eriophyoidea) is a key phytophagous pest of the hazelnut tree. In spring, mites migrate towards the newly formed mixed buds, infesting them and causing swelling (big buds - BB) that develop throughout autumn and winter. Recently, severe hazelnut orchards infestations have been reported strongly reducing productivity per hectare, thus urgently demanding appropriate control measures. In this study we explored the effectivined of low-environmental-impact control strategies against the hazelnut gall mite using entomopathogenic fungi (EPF). Specifically, commercial formulations based on Beauveria bassiana and Lecanicillium muscarium, together with a wild Akanthomyces spp. isolated form hazelnut buds collected in the field were tested. Briefly, the BB were immerged in a 0.5% sodium hypochlorite solution, then each brats were dissected into individual scales and immerged aqueous conidial suspensions of the tested EPF (Naturalis® 9.2x10⁷ cfu/l, Mycotal® 1x10¹⁰ cfu/l, Akanthomyces spp. 1x10¹⁰ cfu/l ) and the control (water) solution for 10 seconds, drying the brats under a laminar flow hood, and finally incubated at 21±1°C for 7 days on 1% water agar in Petri dishes. Mite survival was assessed by quantifying live and dead mites on 30 replicates per treatment at different time points (24, 48, 72, 96 and 168 hours). At the end of the assay, some apparently infected mite specimens were transferred to PDA to attempt reisolation of the fungi. At the end of the assay (168 hours) B. bassiana (10.78±0.02%) and Akanthomyces spp. (2.9 ±0.01%) application resulted as lower relative survival (p<0.01) compared to the control (47.52±0.03%) and L. muscarium (32.10±0.03%). Additional field trials in hazelnut orchards were conducted by BB and nuts immersion using the Naturalis® conidial suspensions used in the laboratory. The control treatment was made by means of water. The experiment was carried out on 20 replicas per treatment. Fourteen days after application, the organs were cut from plant and examined under a dissection microscope (buds) or washed in a 2% bleach + 0.2% dish soap solution (nuts). The BB treated with B. bassiana (17.37±4.63%) showed a lower relative survival rate (p≤0.05; n=20) when compared to the control (36.35±5.84%). Complementary results were found on the nuts population comparison, where reduced mite individuals per nut (p≤0.05; n=20) was also observed when treated with B. bassiana (10.57±3.17 individuals) compared to the control (25.79±5.84 individuals). These results provide important insights into the efficacy of microbial control of eriophyid mites in hazelnut orchards, opening new pathways for integrated pest management strategies.
Acaropathogenic fungi against hazelnut big bud mite Phytoptus avellanae.
Valenzano D.;Laterza I.;Tarasco E.;de Lillo E.
2025-01-01
Abstract
Phytoptus avellanae Nalepa (Acari: Eriophyoidea) is a key phytophagous pest of the hazelnut tree. In spring, mites migrate towards the newly formed mixed buds, infesting them and causing swelling (big buds - BB) that develop throughout autumn and winter. Recently, severe hazelnut orchards infestations have been reported strongly reducing productivity per hectare, thus urgently demanding appropriate control measures. In this study we explored the effectivined of low-environmental-impact control strategies against the hazelnut gall mite using entomopathogenic fungi (EPF). Specifically, commercial formulations based on Beauveria bassiana and Lecanicillium muscarium, together with a wild Akanthomyces spp. isolated form hazelnut buds collected in the field were tested. Briefly, the BB were immerged in a 0.5% sodium hypochlorite solution, then each brats were dissected into individual scales and immerged aqueous conidial suspensions of the tested EPF (Naturalis® 9.2x10⁷ cfu/l, Mycotal® 1x10¹⁰ cfu/l, Akanthomyces spp. 1x10¹⁰ cfu/l ) and the control (water) solution for 10 seconds, drying the brats under a laminar flow hood, and finally incubated at 21±1°C for 7 days on 1% water agar in Petri dishes. Mite survival was assessed by quantifying live and dead mites on 30 replicates per treatment at different time points (24, 48, 72, 96 and 168 hours). At the end of the assay, some apparently infected mite specimens were transferred to PDA to attempt reisolation of the fungi. At the end of the assay (168 hours) B. bassiana (10.78±0.02%) and Akanthomyces spp. (2.9 ±0.01%) application resulted as lower relative survival (p<0.01) compared to the control (47.52±0.03%) and L. muscarium (32.10±0.03%). Additional field trials in hazelnut orchards were conducted by BB and nuts immersion using the Naturalis® conidial suspensions used in the laboratory. The control treatment was made by means of water. The experiment was carried out on 20 replicas per treatment. Fourteen days after application, the organs were cut from plant and examined under a dissection microscope (buds) or washed in a 2% bleach + 0.2% dish soap solution (nuts). The BB treated with B. bassiana (17.37±4.63%) showed a lower relative survival rate (p≤0.05; n=20) when compared to the control (36.35±5.84%). Complementary results were found on the nuts population comparison, where reduced mite individuals per nut (p≤0.05; n=20) was also observed when treated with B. bassiana (10.57±3.17 individuals) compared to the control (25.79±5.84 individuals). These results provide important insights into the efficacy of microbial control of eriophyid mites in hazelnut orchards, opening new pathways for integrated pest management strategies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
