Susceptibility of Dendroctonus simplex to Hypocreales fungi: towards the development of a biological control strategy

Abstract

The use of Hypocreales fungi against bark beetles is an attractive alternative strategy for biological control in forestry. However, fungal inoculation methods remain a major challenge due to the cryptic behaviour of these beetles. Experiments were conducted to evaluate the susceptibility of adult eastern larch beetles, Dendroctonus simplex, to different isolates of Hypocreales fungi and to assess the efficiency of direct inoculation of fungal conidia using an assisted autodissemination device. Among the nine fungal isolates tested, Beauveria bassiana INRS‐242 was selected as the utmost isolate causing a mortality rate of 64.4% of D. simplex adults within 10 days and having a high conidial viability of 81.7%. Using an assisted autodissemination device, a fungal‐coated pouch was a promising contamination chamber. Once it had fallen onto the fungal‐coated pouch, each D. simplex adult loaded an average lethal dose of 2.1 × 109 conidia, which induced a mortality rate of 98.0%. Our results demonstrated the fungal pathogenicity of B. bassiana INRS‐242 against the eastern larch beetles and pointed out the potential of the assisted autodissemination device as an effective method of conidia inoculation. These findings represent the first step to develop a biological control strategy against D. simplex populations.

Entomopathogenic fungus isolates for adult Tuta absoluta (Lepidoptera: Gelechiidae) management and their compatibility with Tuta pheromone

“…Our results corroborate with that reported by Quesada‐Moraga, Martin‐Carballo, Garrido‐Jurado, and Santiago‐Alvarez, (2008), showing that transmission of entomopathogenic fungus M. anisopliae strain EAMa 01/58‐Su within the populations of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), was higher when males were carriers of the pathogen. However, our findings are contrary to that reported by Srei, Lavallée, and Guertin, (2017), who demonstrated that in Dendroctonus simplex LeConte (Coleoptera: Curculionidae), horizontal transmission of B. bassiana isolate INRS‐242 was higher when females were inoculated with the fungus. Our results therefore revealed the potential of T. absoluta population to horizontally transmit the three M. anisopliae isolates, ICIPE 18, ICIPE 20 and ICIPE 665 inocula and induce high mortality rates under laboratory conditions.…”

Horizontal transmission of the entomopathogenic fungal isolate INRS-242 of Beauveria bassiana in emerald ash borer, Agrilus planipennis Fairmaire

“…For the second treatment, only the EAB male was inoculated with the fungus (IM+UF), whereas in the third treatment, just the EAB female was contaminated with the fungus (IF+UM). Fungal inoculation process using the autodissemination device was performed in this experiment [8]. Briefly, each EAB male or female was left walking on the fungal-coated pouch for 1 min.…”

Prospects for deploying microbes against tree-killing beetles (Coleoptera) in Anthropocene

“…The semiochemical baited traps connected to an auto-inoculative device attract insect pests and then contaminate them with the entomopathogen before returning to the environment to infect other pests horizontally or vertically (Dimbi et al, 2003;Ekesi et al, 2007). Such a dissemination approach can protect entomopathogens from UV exposure and rainfall (Srei et al, 2017). For instance, B. bassiana is introduced into a spruce bark beetle, I. typographus population, via an auto-inoculative device (Kreutz et al, 2004).…”