Methodology of the Epilachna varivestis bioassay of antifeedants demonstrated with some compounds from Azadirachta indica and Melia azedarach

Publikations-Art

Zeitschriftenbeitrag

Autoren

Schwinger, M.; Ehhammer, B.; Kraus, W.

Erscheinungsjahr

1984

Veröffentlicht in

Schriftenr. GTZ

Band/Volume

161(Nat. Pestic. Neem Tree Other Top.Plants)/

Seite (von - bis)

181-98

Problems connected with biol. tests of antifeedants are discussed and layout and optimal duration of the bioassay, application of the substance to be tested, and recording and evaluating the antifeedant activity were investigated. All tests were carried out with E. varivestis on Phaseolus vulgaris. Comparison of different test layouts led to the use of one bean leaf, with one-half treated and one-half untreated, in one petri dish (choice test). With this method and using the compds. melianone [6553-27-1] and 3-deacetylsalannin [1110-56-1] the optimal duration of the test period was detd. Different ways to treat the leaves with a methanolic soln. of the compds. to be tested include dipping the leaves, smearing them with a brush, and spraying them by means of a self-constructed sprayer. To det. the consumed leaf area a new photometric method was developed using contact prints of the test leaves on photog. paper. Several components of the neem tree were tested in .ltoreq.9 different concns. and compared the activity of related chem. structures. The substances tested were azadirone [25279-67-8], azadiradion [26241-51-0], 14-epoxyazadiradione [26666-20-6], gedunin [2753-30-2], nimbinene [78916-54-8], 6-deacetylnimbinene [78916-55-9], salannin [992-20-1], 3-deacetylsalannin, and azadirachtin [11141-17-6].