Glazer, I., Department of Entomology and Nematology, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
Salame, L., Department of Entomology and Nematology, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
Dvash, L., Department of Natural Resources, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
Muklada, H., Department of Natural Resources, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
Azaizeh, H., The Institute of Applied Research (Affiliated with University of Haifa), The Galilee Society, Shefa-Amr, Israel, Tel-Hai College, Upper Galilee, Israel
Mreny, R., The Institute of Applied Research (Affiliated with University of Haifa), The Galilee Society, Shefa-Amr, Israel
Markovics, A., Kimron Veterinary Institutes, P.O.B. 12, Bet-Dagan, Israel
Landau, S., Department of Natural Resources, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel

Parasitized animals can self-medicate. As ingested plant phenolics, mainly tannins, reduce strongyle nematode infections in mammalian herbivores. We investigated the effect of plant extracts known to be anthelmintic in vertebrate herbivores on the recovery of the parasitic entomopathogenic nematode Heterorhabditis bacteriophora infecting African cotton leafworm (Spodoptera littoralis). Nematode infective juveniles (IJs) were exposed to 0, 300, 900, 1200, 2400ppm of Pistacia lentiscus L. (lentisk), Inula viscosa L. (strong-smelling inula), Quercus calliprinos Decne. (common oak) and Ceratonia siliqua L. (carob) extracts on growth medium (in vitro assay). In control treatments, 50-80% of IJs resumed development to J4, young and developed adult hermaphrodites, whereas all extracts, except for C. siliqua at 300ppm, impaired IJ exsheathment and development. The highest concentration of I. viscosa extract (2400ppm) had the strongest effect, killing 95% of exposed nematodes. Surviving nematodes did not recover, remaining at the IJ stage. Over the whole cycle, I. viscosa extract inhibited recovery to 25% or less, and did not allow full development to adulthood, whereas 65% of IJs in the control treatment recovered and resumed development, 12% reaching complete maturation within 72h of incubation. When herbivorous S. littoralis larvae were fed with different plant extracts in vivo, I. viscosa had the strongest effect at concentrations above 300ppm, with 90% of insect-invading IJs not developing to parasitic stages, whereas in the control treatment, 85% of IJs resumed development. Exposure to C. siliqua extract also inhibited exsheathment and development of 75% of the IJs. Half of those that resumed development reached full maturation. P. lentiscus and Q. calliprinos extracts also inhibited development of 50% IJs. Our results suggest that H. bacteriophora can be used to study herbal medication against parasites in animals. © 2015 Elsevier Inc.