Exogenous Application of Jasmonic Acid Induces Volatile Emissions in Rice and Enhances Parasitism of Nilaparvata lugens Eggs by theParasitoid Anagrus nilaparvatae

Abstract

Abstract-Jasmonate signaling pathway plays an important role in induced plant defense against herbivores and pathogens, including the emission of volatiles that serve as attractants for natural enemies of herbivores. We studied the volatiles emitted from rice plants that were wounded and treated with jasmonic acid (JA) and their effects on the host-searching behavior of the rice brown planthopper, Nilaparvata lugens (Stål), and its mymarid egg parasitoid Anagrus nilaparvatae Pang et Wang. Female adults of N. lugens significantly preferred to settle on JA-treated rice plants immediately after release. The parasitoid A. nilaparvatae showed a similar preference and was more attracted to the volatiles emitted from JA-treated rice plants than to volatiles from control plants. This was also evident from greenhouse and field experiments in which parasitism of N. lugens eggs by A. nilaparvatae on plants that were surrounded by JA-treated plants was more than twofold higher than on control plants. Analyses of volatiles collected from rice plants showed that JA treatment dramatically increased the release of volatiles, which included aliphatic aldehydes and alcohols, monoterpenes, sesquiterpenes, methyl salicylate, n-heptadecane, and several as yet unidentified compounds. These results confirm an involvement of the JA pathway in induced defense in rice plants and demonstrate that the egg parasitoid A. nilaparvatae exploits plant-provided cues to locate hosts. We explain the use * To whom correspondence should be addressed. E-mail: yglou@zju.edu.cn of induced plant volatiles by the egg parasitoid by a reliable association between planthopper feeding damage and egg presence.

Biosynthesis and emission of insect-induced methyl salicylate and methyl benzoate from rice

“…6B), suggesting that the JA signaling pathway plays a central role in regulation of production of insect-induced MeSA, as in other plant species. While this phenomenon has been observed previously [19], our study suggests that at least part of this regulation is through the modulation of OsBSMT1 expression, which was induced by the JA treatment (Fig. 6A).…”

Differences in Induced Volatile Emissions among Rice Varieties Result in Differential Attraction and Parasitism of Nilaparvata lugens Eggs by the Parasitoid Anagrus nilaparvatae in the Field

“…They were subsequently treated by applying 20 μl of 10 mM jasmonic acid in 50 mM sodium phosphate buffer (titrated with 1 M citric acid until pH = 8) at each damage site (JA). In a previous study, we found that JA treatment induces the release of volatiles in rice, resulting in the attraction of the parasitoid (Lou et al, 2005a). Plants were treated at 17:00 hr, and then the plants were placed in a controlled climate room that was maintained at 28 ± 2°C, 12 hr photophase, and 80% r.h. Fifteen hours after treatment, i.e., at 8:00 hr the next day, plants were used for experiments.…”

“…The detector signal was processed with HP GC Chemstation software. Compounds were identified by comparison of GC retention times with those from our previous studies (Lou et al, 2005a) and those of authentic standards.…”

“…Two days after the plants were introduced into the rice field, they were transferred to the controlled climate room at 28 ± 2°C, 12 hr photophase, and 80% r.h. Each pot of plants was confined to an 11 × 40 cm plastic cage (after herbivores, predators, and parasitoids had been removed). Five days later, the plants were cut off at soil level and dissected under a microscope to record the total and parasitized N. lugens eggs by using the method described in Lou et al (2005a). This experiment was done two times (July 6 and September 27, 2005).…”

“…Previous studies have shown that N. lugens attack or JA treatment alters the volatile profiles of rice plants, and these volatiles are strongly attractive to the egg parasitoid Anagrus nilaparvatae (Lou et al, 2005a,b), a major natural enemy of the rice planthoppers (Cheng and He, 1996). Moreover, the parasitism of N. lugens eggs by A. nilaparvatae on plants that were surrounded by JA-treated plants is more than twofold higher than on control plants in the greenhouse and field (Lou et al, 2005a), implying that augmenting the release of rice-produced attractants has the potential to enhance the effectiveness of the parasitoid in the control of N. lugens. This should be testable, as the volatiles released from different rice varieties in response to N. lugens infestation show distinct differences in attraction of the parasitoid (Ma et al, 2004).…”