Field studies on the efficacy of meliaceous plant preparations against the oak processionary, Thaumetopoea processionae (L.) (Lepidoptera: Thaumetopoeidae)
1999
Breuer, M. | Loof, A. de (Katholieke Univ. Leuven (Belgium). Zoological Inst. Lab. for Developmental Physiology and Molecular Biology)
The efficacy of NeemAzal-T/S, a formulation of the active ingredients of the neem tree, Azadirachta indica, and an enriched Melia azedarach fruit extract was studied under field conditions. The development of caterpillars was monitored on small oak trees sprayed with NeemAzal-T/S (0.5/) and Melia extract (1/), or by application of a NeemAzal-T/S paste to the stems. The results were compared to those obtained from control trees. Already after one week, clear differences could be seen between the experimental variants. In contrast to the control animals, the development of the larvae on trees sprayed with NeemAzal-T/S and Melia extract was retarded. The larvae remained small and appeared to be quite inactive. Feeding damage on the treated trees was quite low, whereas control trees were largely defoliated. Effects after stem application were not as drastic as after spraying, but 100/ mortality was attained within a period of four weeks even under these conditions. Another interesting observation was, that the larvae separated from each other on treated oaks, while caterpillars on untreated oaks always aggregated and afterwards spun a dense nest. During the experiment, predators and parasitoids such as spiders, carabids, scorpionflies and tachinids could be registered, even on the treated trees. These enemies apparently are not repelled by the applied plant preparations.
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