Induction of resistance against the leafminer, Liriomyza trifolii, by jasmonic acid in sweet pepper

Sweet pepper (Capsicum annuum) leaves at the mature stage have strong ovipositional deterrence against Liriomyza trifolii (Burgess) (Diptera, Agromyzidae), whereas the cotyledons are fiercely attacked by the fly. Treatment of the cotyledons with 50 microM and 100 microM of a jasmonic acid (JA) solution caused the plant to acquire strong oviposition deterrence against the leafminer. An HPLC analysis of the JA-treated cotyledons revealed the inducible accumulation of a compound. Based on spectroscopic analysis and chemical methods, the induced compound was identified to be caffeoylputrescine (CP). The accumulated amounts of CP in the cotyledons treated with 0, 10, 50 and 100 microM of JA were 6.0, 43.0, 105 and 140 microg/g fr. wt., respectively. Treatment of the cotyledons with CP resulted in a significant decrease in the number of punctures made by L. trifolii, indicating that the JA treatment enhanced the deterrence against the leafminer by inducing CP accumulation.     

Germination inhibitor from the Japanese cedar Cryptomeria japonica

(1S,6R)-2,7(14),10-Bisabolatrien-1-ol-4-one was identified as a germination inhibitor from the methanol extract of Japanese cedar wood, Cryptomeria japonica. The occurrence of this compound in 1 g fresh wood was 2.0 mg, and showed a maximum of 60% germination inhibition at the dose of 20 mg/filter paper (157 microg/cm(2)) against both of lettuce and rice seeds for 4 d. A selective activity between Dicotyledoneae and Monocotyledoneae seeds was not observed.     

Nitrogenous ovipositional deterrents in the leaves of sweet pepper (Capsicum annuum) at the mature stage against the leafminer, Liriomyza trifolii (Burgess)

Mature leaves of the sweet pepper, Capsicum annuum, exhibited resistance against the American serpentine leafminer, Liriomyza trifolii (Burgess), Agromyzidae. Based on bioassay-guided fractionation, three compounds, namely 4-aminobutanoic acid, (2S,4R)-4-hydroxy-1-methyl-2-pyrrolidine carboxylic acid and 4-amino-1-beta-D-ribofuranosyl-2(1H)-pyrimidinone, were isolated from the leaves of sweet pepper. These compounds had significant oviposition deterrence towards adult flies of L. trifolii from laying their eggs on host plant leaves treated at 3.70, 16.60 and 6.45 microg/cm(2), respectively.     

Feeding stimulant in Cinnamomum camphora for the common bluebottle, Graphium sarpedon nipponum (Lepidoptera: Papilionidae)

The acceptance of camphor tree (Cinnamomum camphora) as a host plant for the larvae of common bluebottle (Graphium sarpedon nipponum) was explained by the presence of feeding stimulants in the leaves. When the active methanol extract of C. camphora leaves was separated into hexane and water layers, both layers showed high feeding activities for the larvae of G. sarpedon nipponum. Bioassay-guided fractionation of the hexane layer resulted in the isolation of a highly active compound, which was identified as a-linolenic acid by nuclear magnetic resonance spectrometry and gas chromatography-mass spectrometry.     

Ovipositional deterrent on mature stage of sweet pepper, Capsicum annuum, against Liriomyza trifolii (Burgess)

Liriomyza trifolii (Burgess), the American serpentine leafminer fly, is a well-known serious pest in the world. This insect species attacks plants of more than 21 families including Solanaceae plants. A sweet pepper, Capsicum annuum (Solanaceae), on mature stage, however, shows resistance to this leafminer fly. This resistance is based on the ovipositional deterrent in the sweet pepper leaf against the fly species. Based on the bioassay guided fractionation, phytol [(2E)-3,7,11,15-tetramethyl-2-hexadecen-1-ol] was isolated and identified as an ovipositional deterrent against this insect species. The yield of this compound was 815 microg/g fresh leaf of C. annuum. This compound completely deterred the females from laying their eggs on host plant leaves treated at 35.2 microg/cm2.     

Repellents in the Japanese cedar,Cryptomeria japonica,against the pill-bug,Armadillidium vulgare

Sandaracopimarinol and (1S,6R)-2,7(14),10-bisabolatrien-1-ol-4-one were isolated and identified from Cryptomeria japonica as repellents against Armadillidium vulgare which is well known as an unpleasant pest in the house and as vegetable pest in Japan. These compounds strongly repelled A. vulgare when they were combined, although each compound alone did not show any activity.     

Induction of 2-cyanoethyl-isoxazolin-5-one as an antifeedant against the tobacco cutworm (Spodoptera litura) by jasmonic acid in sweet pea leaf

ABSTRACT

Although sweet pea (Lathyrus odoratus) beans contain toxic β-aminopropionitrile, the plant itself is readily attacked by insects and is, therefore, protected through the use of pesticides. Consequently, the induction of L. odoratus resistance to insect attack via exogenous treatment is promising for pest control development. Screening of inducible elicitor effects showed that treatment of sweet pea foliage with jasmonic acid (JA) can induce antifeeding-based resistance to tobacco cutworm (Spodoptera litura) larvae. Spectroscopic analysis identified 2-cyanoethyl-isoxazolin-5-one (2-CEIX) as the antifeedant with a half-maximal effective concentration of 33.6 µmol/g fr. wt., i.e., exogenous JA treatment induced antifeeding activity due to the accumulation of 2-CEIX. Moreover, 2-CEIX-induced mortality of S. litura larvae was evaluated by a dipping test and the half-maximal lethal dose was determined to be 5.9 mg/mL. Therefore, 2-CEIX was concluded to be a suitable induced resistance target for elicitors or a lead compound for insecticide development.