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Comparative growth inhibitory and antifeedant effects of plant extracts and pure allelochemicals on four phytophagous insect species
Author(s) -
Akhtar Y.,
Isman M. B.
Publication year - 2004
Publication title -
journal of applied entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0931-2048
DOI - 10.1046/j.1439-0418.2003.00806.x
Subject(s) - allelopathy , biology , trichoplusia , bioassay , cabbage looper , diamondback moth , plutella , thymol , botany , instar , origanum , toxicology , horticulture , food science , larva , noctuidae , germination , essential oil , genetics
Antifeedant and growth inhibitory effects of crude plant extracts ( Melia volkensii and Origanum vulgare ) and pure allelochemicals (digitoxin, cymarin, xanthotoxin, toosendanin, thymol and trans ‐anethole) were investigated in the cabbage looper ( Trichoplusia ni ), and in the armyworm ( Pseudaletia unipuncta ) using different bioassays. Antifeedant effects of M. volkensii , O. vulgare and thymol were investigated in larvae of the diamondback moth ( Plutella xylostella ), and of O. vulgare and thymol in the Mexican bean beetle ( Epilachna varivestis ), using leaf disc choice bioassays. M. volkensii was the most potent growth inhibitor for T. ni and P. unipuncta (dietary EC 50 = 7.6 and 12.5 p.p.m., respectively) of all the test substances. Cymarin was the second most potent growth inhibitor (EC 50 = 132.0 p.p.m.) for T. ni . The most effective feeding deterrents for third instar T. ni larvae were xanthotoxin and M. volkensii (DC 50 = 0.9 and 8.3 μ g/cm 2 , respectively). M. volkensii was also the most potent feeding deterrent for third instar P. unipuncta , P. xylostella and adult E. varivestis (DC 50 = 10.5, 20.7 and 2.3 μ g/cm 2 , respectively). Because of interspecific differences in response to feeding deterrents and the lack of a strong relationship between EC 50 and DC 50 values, we recommend testing a battery of bioassay species with candidate compounds and the use of more than one bioassay. Based on their growth inhibitory and feeding deterrent properties, some of these plant extracts and pure allelochemicals have potential for use as alternative crop protectants against a number of pest species.