The azadirachtin-containing neem extract AZT-VR-NR from the Institut fur Phytopathologie und Angewandte Zoologie of the Universitat Giessen (Prof. Dr. H. Schmutterer) was tested at different concentrations - partly after storage of several months - against H. abietis and L. monacha and at only one concentration against D. inconspicua. H. abietis: Forced feeding with a diet after dripping wet treatment (60 g and 120 g a.i./ha) did not affect the beetles. Antifeedant effects could only be obtained by submerging in a 60 % broth. L. monacha: In laboratory experiments, old larvae (L III-V) stopped feeding when supplied with dripping wet treated spruce twigs (30 g and 60 g a.i./ha), they could not or only incompletely pupate or the pupae did not release imagines. As compared to untreated larvae, the effect amounted to 88,9% and 77,8%, respectively. - Younger larvae (L II/L III) were fed with treated, also weather-protected diet (5 and 15 g a.i./ha; application 9 months after delivery . Whereas pupation in the untreated control (99 %) terminated till the 32nd day, the development of larvae on the treated diet was delayed considerably. Within 51 days, the low dosage led to 79 % and the high dosage to 5% pupation. From the number of healthy eggs produced after further rearing, the per cent effect can be calculated (Reduction of eggs produced per female compared to untreated). It amounted to 89,0% with the lower and to 100% with the higher dosage. When the experiment was repeated with a diet that was treated under field conditions (15 g a.i./ha; application almost 1 year after delivery) and thus exposed to the influence of the weather during the experimental period, the three variants showed a strong dependence of the effects of the preparations on the weather conditions. On spruce twigs treated 8 days before the larvae were placed on them, all larvae had pupated after 32 days like on the untreated diet (98% and 99%, respectively). The production of eggs was reduced 14,8%. In the two other variants, which are characterized by sunny respectively rainy weather after application, the larvae were applied immediately after drying of the deposit. In both variants, the development of the larvae dragged on to maximal 56 days. Of the larvae on whose diet it had rained, 88% pupated. Egg-reduction amounted to 51,5%. On the twigs treated at sunshine, 51% of the larvae pupated, egg-reduction was 82,7%. D. inconspicua: Forced contact after application of the 8 to 9 months old preparation (45 g a.i./ha) was survived by the tachina flies without damage. The reduction of eggs laid into host larvae reached 18,5% as compared to the untreated control. Host larvae into which contaminated tachina flies had laid their eggs, released 74,5% healthy tachina flies of the first succeeding generation as compared to 70,3% in the control. When the first succeeding generation was reared further, each female, originating from contaminated tachina flies, produced 4,91 tachina flies of the second generation, in the control 3,36.
