Submitted to: Biocontrol
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2015
Publication Date: 4/2/2015
Citation: Ulrich, K.R., Feldlaufer, M.F., Kramer, M.H., St. Leger, R.J. 2015. Inhibition of the entomopathogenic fungus Metarhizium anisopliae in vitro by the bed bug defensive secretions (E)-2-hexenal and (E)-2-octenal. Biocontrol. Doi: 10.1007/s10526-015-9667-2.
Interpretive Summary: Due to insecticide resistance, bed bugs may not be effectively controlled by many chemicals formally used for that purpose. Therefore, new treatment methods and strategies are being sought to control this blood-sucking pest. While a fungus that can attack and kill bed bugs exists, we showed that chemicals produced by the bed bug for defensive purposes were able to kill the fungus at an early stage. This may render the fungus not particularly useful for bed bug control purposes. This information will be used by scientists exploring new ways to control bed bugs.
Technical Abstract: The two major aldehydes (E)-2-hexenal and (E)-2-octenal emitted as defensive secretions by bed bugs Cimex lectularius L. (Hemiptera: Cimicidae), inhibit the in vitro growth of Metarhizium anisopliae (Metsch.) Sokorin (Hypocreales: Clavicipitaceae). These chemicals inhibit fungal growth by direct contact with fungal-inoculated agar media, and via indirect exposure (“fumigation”). In vitro exposure of M. anisopliae conidia to (E)-2-octenal by fumigation for as little as 0.5h was sufficient to inhibit all fungal growth. Bed bugs placed on filter paper treated with M. anisopliae conidia, but not exposed to (E)-2-octenal, exhibited 100% mortality after one week. However, bed bugs placed on fungal-treated filter paper and exposed to (E)-2-octenal at 1h experienced less than 9% mortality. The inhibition of fungal growth by bed bug aldehydes is discussed in the context of other biotic and abiotic barriers to infection.