Effects of azadirachtin after systemic uptake intoBrassica oleracea on larvae ofPieris brassicae |
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Authors: | S Arpaia and J J A van Loon |
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Institution: | (1) Department of Entomology, Wageningen Agricultural University, P.O. Box 8031, 6700 EH Wageningen, The Netherlands;(2) Present address: C.R.S.A. Metapontum Agrobios, S.S. Jonica 106 km 448.2, 75010 Metaponto (MT), Italy |
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Abstract: | Petioles of intact cabbage leaves were placed in azadirachtin solutions for 24 h. Azadirachtin or active metabolites of this
compound appeared to be translocated systemically as performance of first instar larvae ofPieris brassicae L. placed on disks from those leaves was affected. The position within a leaf from which disks were excised did not affect
the extent of these effects, indicating a homogeneous distribution of active compounds in the laminar tissue. At doses ranging
from 1–10 ppm of azadirachtin in the solution taken up by the leaves, gain of larval fresh weight and leaf area consumed were
reduced. These effects were dose dependent up to 60–90 ppm. At 10 ppm and higher doses no larva reached the second instar
within 72 h. Mortality during the 72 h period was highest at 10 ppm, due to the coincidence of lethal action with ecdysis
in combination with the effect on developmental rate. Azadirachtin solutions applied directly to the surface of leaf disks
in order to produce known doses on a leaf fresh weight basis gave results similar to the systemic treatment for weight gain,
leaf area consumed and developmental rate, while mortality was higher in the latter treatment. |
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Keywords: | azadirachtin antibiosis systemic uptake translocation Pieris brassicae bioassay performance behaviour Brassica oleracea |
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