Bioactivity of compounds from Acmella oleracea against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) and selectivity to two non‐target species

Abstract

The crude hexane extract of A. oleraceae showed high insecticidal activity and can be used to control T. absoluta in organic or conventional crops. Quantification of LD(50) values of isolated compounds against T. absoluta showed that alkamides could serve as potent insecticides for T. absoluta control programmes. Spilanthol was the main alkamide active isolated. This alkamide is the most promising as it has the highest insecticidal activity and is selective to non-target organisms.

Alkamides: a critical reconsideration of a multifunctional class of unsaturated fatty acid amides

“…In accordance with previous findings (Kadir et al 1989) 92a was shown to be the most active compound being approximately 5 times more toxic than the commercial permethrin and a good deal more potent than the seed extract from Neem-tree, Azadirachta indica. The two acetylenic derivatives 169a and 169g exhibited activities similar to that of permethrin (Moreno et al 2012). Bioassay-guided chromatographic fractionation of the leaf extract of A. oleracea led to a mixture of active alkamides consisting of nona-2Z-en-6,8-diynoic (187c) and deca-2Z-en-6,8-diynoic acid phenethylamide (178c).…”

“…However, in antifeedant tests 169a showed significantly higher weight reduction of the larvae of H. zea compared to 92a and 85a . In search of ecofriendly and easily biodegradable naturally-occurring insecticides against Tuta absoluta (Lepidoptera), one of the key pests of tomato crops, hexane and ethanol extracts from 23 mostly South American plant species out of 16 different families were tested (Moreno et al 2012). The hexane extract from aerial parts of A. oleracea exhibited by far the highest activity.…”

Tomato leafminer [(Tuta absoluta Meyrick) (Lepidoptera: Gelechiidae)] and its current ecofriendly management strategies: A review

“…The observed larval mortality is better than Neem Azal T/S 0.3% registered with active ingredient of azadiractin which kills 84 to 87% of first to fourth instars larvae after 14 days of exposure (Yankova et al, 2014). In the same way, the petroleum ether extract obtained from Jatropha also achieved 18 to 25% egg and 87 to 100% larval death on T. absoluta after being exposed for 4 days in different concentration (Moreno et al, 2011;Kona et al, 2014). The extracts obtained from jojoba (Simmondsia chinsis) seed at 100% concentration resulted in 75% mortality on 2nd larval instars of T. absoluta (Abdel-Baky and Al-Soqeer, 2017).…”

“…The hexane and ethanol extracts from aerial parts of Acmella oleracea exhibited the highest activity, causing (100 and 88%) mortality, respectively, in T. absoluta at a concentration of 10 μg of extract per mg of an insect after 6 h of exposure (Moreno et al, 2011). The bioactivity of A. oleracea is due to alkamides present in the plant.…”

“…Three alkamides were identified in the bioactive fractions of the hexane extract of A. oleracea [spilanthol, (E)-Nisobutylundeca-2-en-8, 10-diynamide and (R, E)-N-(2-methyl butyl) undeca-2-en-8,10-diynamide]. The results showed that all of the compounds isolated had a high insecticidal activity that was at least as toxic as permethrin, a pyrethroid recommended for control of T. absoluta (Moreno et al, 2011). The mechanism of action is that active alkamides found in A. oleracea has not yet been determined.…”