Behavioral Responses of a Generalist Pest, Spilosoma Obliqua Walker, Towards the Leaf Surface Wax Chemicals of Three Types of Jute Crop and Implications in Pest Management

Behavioral responses of a generalist pest, Spilosoma obliqua Walker (Lepidoptera: Arctiidae), towards the leaf surface wax chemicals of three types of jute crops (white jute, Corchorus capsularis, tossa jute, C. olitorious,, and mesta jute or kenaf, Hibiscus cannabinus [Malvaceae]) and their implications in pest management was studied under laboratory conditions. The GC-MS and GC-FID analyses of the jute leaf epicuticular waxes indicated the presence of 27 n-alkanes, having chain lengths from n-C14 to n-C36 and 14 free fatty acids (FFAs) having chain lengths from C12:0 to C22:0. Among the identified n-alkanes and FFAs of selected jute cultivars n-C34 (144.397±6.971 µg leaf−1) and C16:1 (37.034±0.848 µg leaf−1) of tossa jute leaves were most abundant. The host preference (white jute> tossa jute > mesta jute) of S. obliqua was evaluated simultaneously by olfactory, visual, and tactile recognition, as valid for other lepidopteran species. For olfaction [females], oviposition [gravid females], and feeding [larvae]) in S. obliqua, the most stimulating combined-synthetic-mixture of epicuticular wax components was represented by 4 n-alkanes (n-C16, n-C18, n-C20, n-C22) and 5 FFAs (C16:1, C16:0, C18:0, C20:0, C22:0) in mixture at leaf equivalent (µg leaf−1) amounts (195.209±2.950 µg, 119.777±1.857 µg, and 50.567±3.508 µg, respectively) in white jute, tossa jute, and mesta jute, respectively. Thus, the present study suggests that the synthetic blends of 4 n-alkanes and 5 FFAs of respective jute crops can be used as lures to develop baited trap as a part of integrated pest management (IPM) of S. obliqua for sustainable jute cultivation.

A comparative study on tribological properties of leaf-surface waxes extracted from coastal and inland plants

Purpose This paper aims to explore the leaf-surface wax as green lubricant additive and compare the tribological properties between coastal and inland leaf-surface waxes of the same species plant. Design/methodology/approach The leaf-surface waxes were extracted from the leaves of Robinia pseudoacacia cv. Idaho and Populus nigra in coastal and inland areas, and then the compositions of the four kinds of leaf-surface waxes were characterized using a gas chromatography–mass spectrometry. The tribological properties of these leaf-surface waxes as lubricant additives in the base oil of synthetic ester (SE) were investigated by an MFT-R4000 reciprocating friction and wear tester. As well as the surface morphologies and chemical compositions of the wear scars were characterized by a scanning electron microscope and time-of-flight secondary ion mass spectrometry, respectively. Findings The results indicate that all the leaf-surface waxes as additives can effectively improve the friction reduction and anti-wear performances of SE for steel–aluminum friction pairs. Therein, coastal leaf-surface waxes have better tribological performances than inland leaf-surface waxes, which are attributed to that the leaf-surface waxes extracted from coastal plants can form a better protective film on the worn surface throughout the friction process. Originality/value This paper investigated a new kind of environmentally friendly lubricant additive and compared the tribological properties of the leaf-surface wax extracted from coastal and inland plants. The associated conclusions can provide a reference to explore the tribological performances of leaf-surface wax as green lubricant additive.