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>APO-IDEA | |||||||||||||||||||||||||||
I The aim of this work was to investigate the effects of fungal pathogens M. anisopliae, H. thompsonii and A. oligospora on Varroa destructor in order to evaluate their potential as biological control agents that could be used in beekeeping. Two different concentrations of conidial suspensions (10*7– 10*5) were used to cover wax coated Petri dishes in which adult varroa mites (4 per dish) were placed. The mites were fed with fresh larvae (2 per dish) every 24 hours, when observations were carried out in order to count and examine the dead mites, which were collected and treated to assess the presence of internal hyphae.With the higher fungal concentration, a significant difference among the experimental groups was found (c *2= 23.086, P<0.01). In particular, mites treated with the higher concentration of M. anisopliae died significantly earlier than the other fungus treated and control mites. Macroscopic presence of fungal colonization on the mites was not observed in any test but the relevant difference in the times the mites took to die strongly suggests that the fungus caused the mites’ early death. M. anisopliae is known to produce several toxic metabolites, destruxins: it is possible that the strain of M. anisopliae we used produced such mycotoxins which elicited a narcotic effect on the mites without a direct fungal invasion being necessary. The
results of this trial show that M. anisopliae
can be effective against Varroa in vitro. This makes it a potential
candidate for biological control of the mite. Trials are under course
to evaluate whether M. anisopliae can express its pathogenic
activity in field conditions and to investigate the role and action of
destruxins. |
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Marco
Lodesani [1], Cecilia Costa[1], Paola Nipoti [1], Antonio Prodi [2]