In planta bioassay on the effects of endophytic Beauveria strains against larvae of horse-chestnut leaf miner (Cameraria ohridella)

In this study, laboratory bioassays were conducted to determine the ability of local Beauveria strains to colonize horse-chestnut leaves endophytically and test their antagonistic activity against C. ohridella in colonized leaves. Two strains of Beauveria bassiana (AM_EF0111 isolated from horse-chestnut leaf tissue and AM_EP0715 isolated from a C. ohridella pupa) and one strain of B. pseudobassiana (AM_SO1015 obtained from soil) were used for in planta bioassays. The selected strains demonstrated high virulence to leaf miner pupae after a topical treatment with spore suspensions. LC50 ranged between 2.49 and 3.19 × 106 conidia ml-1. Horse-chestnut saplings were inoculated with the fungi through their direct immersion into spore suspensions (107 conidia ml-1). Endophytic colonization was successful and a mean colonization rate reached 57.44–66.08% 15 days post-inoculation. It decreased over time for all strains, but the fungi were still present in leaf tissue 54 days post-inoculation. AM_EF0111 strain was significantly more effective in colonizing saplings than AM_SO1015 and AM_EP0715. Fungus-colonized and untreated (control) saplings were infested with the leaf miner 31 days after inoculation and development of larval mines was monitored. In Beauveria-colonized saplings, damage by leaf miner was significantly lower compared to control plants. On day 23 post-infestation, the damaged leaf area of colonized leaves was 5-times smaller compared to control saplings. The negative...
Source: Biological Control - Category: Biology Source Type: research