engleski

Effectiveness of entomopathogenic Beauveria pseudobassiana on Corythucha arcuata in laboratory conditions

Invasive pest oak lace bug (Corythucha arcuata), (Hemiptera: Tingidae) was first recorded in eastern Croatia in 2013 in lowland stands of pedunculate oak (Quercus robur L.), from where it expanded to the west causing summer yellowing and intensive chlorotic damages of oak leaves. In 2018 entomopathogenic fungus Beauveria pseudobassiana Rehner et Humber (Hypocreales Cordycipitaceae) was isolated from several dead C. arcuata adults found in moss, where one part of population usually overwinters. Two isolates were used for testing of fungus virulence against C. arcuata under laboratory conditions. After preparation of conidial suspensions with desired 1 x 108 concentrations healthy adults of C. arcuata were treated by spraying the moss where they were previously put on. Results showed no difference in mortality rate between isolates (96-97%), but isolate BBCNK1 produced mycosis value of 49 % which was higher than mycosis value of 32 % produced by isolate BBC10, with 4 % of mycosis value in control. In nature these results indicate possible rise of entomopathogenic B. pseudobassiana natural inoculum up to 12 X. Moreover, we estimated the number of overwintering adults in 1 m2 of moss by counting them and calculating their average number in 6 m2 of moss collected in six different locations in infested oak forest. Results demonstrated high rate of dead overwintering individuals, with approximately 15 % of them infested by various entomopathogenic fungus. The results presented here will be beneficial for future investigations of effectiveness of naturally occurring B. pseudobassiana on C. arcuata in field conditions.

conidial suspensions ; invasive species ; moss ; oak lace bug ; overwintering adults

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