Submitted to: Journal of Chemical Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/1/2010
Publication Date: 10/16/2010
Citation: Rojas, M.G., Morales Ramos, J.A. 2010. Tri-trophic level Impact of Host Plant Linamarin and Lotaustralin on Tetranychus urticae (Mesostigmata: Tetranychidae) and its predator Phytoseiulus persimilis (Prostigmata: Phytoseiidae). Journal of Chemical Ecology. 36:1354-1362. Interpretive Summary: The two-spotted spider mite is a major pest of at least 150 economically important plants. Predatory mites are produced and sold in the hundreds of millions per year for use in the biological control of this pest. Our study focused on the impact of some plant defensive chemicals on the spider mites and its predators. We confirmed the presence of plant defensive chemicals in the leaves of Henderson Lima bean plants. Spider mites were found to possess a significant tolerance to the plant chemical defenses while the predatory mites are quite sensitive to the same chemicals. This is important because it provides information on the impact of some plant varieties on biological control agents and will enable growers to make decisions on the choice of the plant varieties based on their compatibility to biological control agents.
Technical Abstract: The impact of linamarin and lotaustralin content in the leaves of Phaseolus lunatus L. on the second and third trophic levels was studied in Tetranychus urticae (Koch) and its predator Phytoseiulus persimilis Athias-Henriot. Chemical analyzes showed that the content of linamarin was higher in terminal trifoliate leaves (435.5 ppm) than in primary leaves (142.1 ppm) of Henderson bush lima beans. However, linamarin concentrations were reversed in the second trophic level showing higher concentrations in spider mites feeding on primary leaves (429.8 ppm) than those feeding on terminal trifoliate leaves (298.2 ppm) of lima bean plants. The concentration of lotaustralin in primary lima bean leaves was 103.12 ppm and in spider mites feeding on this leaves was 175.0 ppm. Lotaustralin was at undetectable levels in lima bean terminal trifoliate leaves and it was absent in mites feeding in these leaves. Fecundity of spider mites feeding on lima bean leaves (primary or trifoliate) was not significantly different than mites feeding on red bean, P. vulgaris L., primary leaves. However, the progeny sex ratio (in females per male) of spider mites feeding on lima bean leaves was significantly lower than progeny of spider mites feeding on red bean leaves (control). The effect of linamarin was amplified in the third trophic level. Fecundity and progeny sex ratio of P. persimilis were both significantly affected by the concentration of linamarin present in the prey.