Effects of tannin-rich host plants on the infection and establishment of the entomopathogenic nematode Heterorhabditis bacteriophora.
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, 2400 ppm 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 300 ppm, impaired IJ exsheathment and development. The highest concentration of I. viscosa extract (2400 ppm) 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 72 h of incubation. When herbivorous S. littoralis larvae were fed with different plant extracts in vivo, I. viscosa had the strongest effect at concentrations above 300 ppm, 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.
Department of Entomology and Nematology, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel. Electronic address: glazerit@agri.gov.il.
Itamar
I
Glazer
Department of Entomology and Nematology, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
Liora
L
Salame
Department of Natural Resources, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
Levana
L
Dvash
Department of Natural Resources, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
Hussein
H
Muklada
The Institute of Applied Research (Affiliated with University of Haifa), The Galilee Society, Shefa-Amr 20200, Israel; Tel-Hai College, Upper Galilee 12208, Israel.
Hassan
H
Azaizeh
The Institute of Applied Research (Affiliated with University of Haifa), The Galilee Society, Shefa-Amr 20200, Israel.
Raghda
R
Mreny
Kimron Veterinary Institutes, P.O.B. 12, Bet-Dagan 50250, Israel.
Alex
A
Markovics
Department of Natural Resources, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
SergeYan
S
Landau
D000818:Animals; D006790:Host-Parasite Interactions / Q000187:drug effects / Q000502:physiology; D010575:Pesticides / Q000737:chemistry / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology; D017168:Rhabditida / Q000187:drug effects / Q000472:pathogenicity*; D018411:Spodoptera / Q000469:parasitology*; D013634:Tannins / Q000494:pharmacology*
D010575:Pesticides; D010936:Plant Extracts; D013634:Tannins
Exsheathment; Heterorhabditis bacteriophora; Parasitic establishment; Recovery; Spodoptera littoralis; Tannins