Repellency of zerumbone identified in Cyperus rotundus rhizome and other constituents to Blattella germanica

Abstract

The compounds 1,8-cineole and zerumbone (ZER) from the Cyperus rotundus rhizome along with another 11 previously identified rhizome essential oil constituents and α-humulene, which lacks the only carbonyl group present in ZER, as well as binary mixtures of ZER and seven active compounds were tested for repellency to male B. germanica. The results were compared to N,N-diethyl-3-methylbenzamide (deet). In filter-paper choice tests, ZER was the most repellent compound, and α-humulene was ineffective, which indicates that the α,β-unsaturated carbonyl group of ZER is a prerequisite component for repellency. At 81.5 μg cm−2, enhanced repellency was produced by binary mixtures of ZER and 1,8-cineole, (+)-dihydrocarvone or (R)-(+)-limonene (70:30, 50:50 and 30:70 ratios by weight). These mixtures were very effective against male B. germanica within 24 h and were more repellent than a single compound or deet alone. The optimum ZER content was determined to be more than 50%. In Ebeling choice box tests at 652.4 μg cm−2, these compounds and deet resulted in complete repellency to intact male B. germanica, while they exhibited 35–47% repellency to antennectomized male one. Mixtures formulated from the active constituents of the C. rotundus rhizome could be useful as potential repellents for controlling B. germanica.

Primary screening and application of repellent plant volatiles to control tea leafhopper, Empoasca onukii Matsuda

“…Previous studies have shown that both DMDS and 1,8-cineole can act as a repellent or fumigant against many pest species. 17,19,20,32,36,[40][41][42][43][44] Moreover, DMDS was shown to be an attractant for the main predators of Delia radicum. 32 Thus, in future studies, it will be important to evaluate the impact of slow-release blend-5 on other arthropod pests and their natural enemies in the tea agro-ecosystem.…”

“…This might be the result of decreased densities of leafhopper adults caused by the repellent effect, because the incubation period of leafhopper egg is ∼ 8 days and the density of leafhopper adults was decreased significantly by 5 days after application. Previous studies have shown that both DMDS and 1,8‐cineole can act as a repellent or fumigant against many pest species . Moreover, DMDS was shown to be an attractant for the main predators of Delia radicum .…”

“…The boiling point of 1,8‐cineole (174 °C) is higher than that of DMDS (110 °C) and allyl methyl sulfide (89 °C) at atmospheric pressure (http://www.chemspider.com). Studies have shown that multicomponent mixtures of phytochemicals have greater repellency against various insect species than do the corresponding single compounds . Therefore, to formulate an efficient repellent for leafhoppers, the three repellent compounds were mixed in different proportions.…”

“…Consequently, to suppress leafhopper populations, the repellent should be combined with other pest management tactics, for example, with an attractive ingredient to build a push–pull system. This system is an effective means of pest behavioural manipulation and has been used successfully to manage several insect pests . A typical example is the combination of a neem seed extract spray (repellent) with an attractive trap crop to protect cotton crops from Helicoverpa armigera (Hübner) and Helicoverpa punctigera (Wallengren) in Australia .…”

“…Studies have shown that multicomponent mixtures of phytochemicals have greater repellency against various insect species than do the corresponding single compounds. [34][35][36] Therefore, to formulate an efficient repellent for leafhoppers, the three repellent compounds were mixed in different proportions. Although there was no significant difference in repellency, the ternary mixture (blend-1) was more repellent than the binary mixture (blend-2).…”