EFFICACY OF A NOVEL NEEM OIL FORMULATION (RP03TM) TO CONTROL THE POULTRY RED MITE DERMANYSSUS GALLINAE

The poultry red mite (PRM) Dermanyssus gallinae is of major concern for the poultry industry. Several chemicals are effective against PRM, but acaricide resistance, the limited number of active ingredients, and the risk of residues create a demand for alternative products, such as plant-derived acaricides. We investigated the efficacy of neem oil against D. gallinae on a commercial laying egg farm with a high infestation level. The farm building was arranged in four blocks of cages, each consisting of two adjacent lines arranged over four tiers. A novel formulation of 20% neem oil dilution from a 2,400 ppm azadirachtin-concentrated stock (RP03TM) was administered by nebulization three times, at three day intervals. Using corrugated cardboard traps, mite density was monitored before, during and after treatment. Following trap removal, mites were frozen and their numbers were estimated as total weight. The results were analyzed through multi-factorial ANOVA with trap position and time as criteria predictors. Mite populations in the treated block showed a 94.65%, 99.64% and 99.80% reduction after the first, second and third administration, respectively. A reduction in mite population was observed also in buffer (59.93%, 75.68% and 83.68%) and control blocks (63.24%, 80.02% and 82.27%). Trap position was the most significant variable according to the analysis run, as well as the interactive term ‘time/trap position’. Trap position showed a mean mite log-reduction of ca. 2.2-2.4 for the treated block, while in the control and buffer areas the mean reduction was 0.8 and 1.3, respectively. The reduction rate of the mite population was significantly higher for treated block (p<0.001) compared to the buffer and control blocks. Nevertheless, it was also possible to observe a reduction in the population of the latter two blocks. It is postulated that forced ventilation may have spread the product, affecting mite density in the buffer and control block. This result was independent from the effect of time and it suggests strong bioactivity of neem, and more specifically the patented neem-based RP03TM, against D. gallinae. The treatment was most effective in the 10 days following the first application, and its effects persisted for over two months. Further studies will aim to reduce the treatment schedule and neem concentration to overcome unwanted effects of treatment recorded on equipment and eggs, as related to the oily consistence and smell of the product.