Test of semiochemicals and a resistant wheat variety for Russian wheat aphid management in South Africa

Abstract

Aphid behaviour-modifying semiochemicals were tested against Russian wheat aphid Diuraphis noxia in South African wheat. Volatile substances from plant essential oils, methyl salicylate, 1,8-cineole and menthol were tested in the laboratory and field in combination with the D. noxia-susceptible wheat variety Betta and the resistant variety Elands. All three substances were repellent to D. noxia in olfactometric tests. Diuraphis noxia settled less on Elands plants that had been exposed to the volatiles, whereas the effect of the volatiles on D. noxia settling on Betta was less obvious. A slow-release pellet formulation was used to apply semiochemicals in wheat in replicated plot field trials in 2004 and 2005. In 2004, semiochemicals reduced aphid populations in Elands, but led to increased aphid populations in Betta. Further, the impact of the chemicals on aphid numbers and grain quality (thousand grain weight) varied according to plant variety, indicating an interaction between semiochemicals and plant resistance ⁄ variety.

Influence of Garlic Intercropping or Active Emitted Volatiles in Releasers on Aphid and Related Beneficial in Wheat Fields in China

“…Although no significant difference in mummified aphids densities were seen between fields with garlic oil blend and control was measured, ladybeetle population density in fields with garlic oil blend and mummified aphids densities in fields with diallyl disulfide were significantly higher than those in control fields. A significant effect of semiochemicals treatment on aphids and their natural enemies was observed between susceptible (Beijing 837) and resistant (Zhengzhou 831) varieties, possibly due to complex interactions between the chemical, plant variety and growing environment (Prinsloo et al 2007). 1 000-grain weight and yield of wheat were also increased in treatment fields, except for the 1 000-grain weight in the GOB field for Zhengzhou 831, and there were no differences among WGI, GOB and DD except in yield of DD treatments for Zhengzhou 831.…”

“…Aphid perception of volatile cues is adapted for avoidance of non-host plants, and they can detect a wide range of chemical compounds (Pickett and Glinwood 2007;Prinsloo et al 2007). Garlic oil blend and diallyl disulfide are components of the essential oils of garlic, which represent non-hosts to cereal aphids, and are likely to be unsuitable for their orientation.…”

“…Volatile agents produced by M. minutiflora repelled female stem-borers and attracted foraging female C. sesamiae (Khan et al 1997). Due to the inherent variability, an important modification of this method is the external application of volatile semiochemicals in the field, which have a stabilizing effect and may reduce populations of the aphids Diuraphis noxia (Prinsloo et al 2007), and Rhopalosiphum padi (Ninkovic et al 2003). Essential oils, obtained by steam distillation of plant foliage, and even the foliage itself of certain aromatic plants have traditionally been used to protect stored grain and legumes, and to repel flying insects (Isman 2000).…”

Potential for the Use of Exogenous Chemical Elicitors in Disease and Insect Pest Management of Conifer Seedling Production

“…4). Slow-release paraffin wax pellets have been used to release MeSA in wheat fields [52]. The potted seedlings treated at nurseries may also have better protection against various biotic stresses in their planting sites, particularly if the elicitor is still active in the pot soil surface or in paste applied on bark surface.…”

Experimental Model for Biological Control of Stored Grain Pests

“…In case of attractive effect of the oil bait, the diatomaceous earth could be applied together for enhancing the killing effect on S. granarius. Beside of the VOCs, insect interactions were already expressed in repellence or like insecticidal effect [3][4][5][6][7]. Many other researches had studied the effect of some botanical VOCs on the development and behaviour of some important natural enemies of some pest in order to enhance the level of natural biological control [8][9][10][11].…”