CABI scientists and their partners from Ghana, including the Plant Protection and Regulatory Services Directorate (PPRSD), Savanna Agricultural Research Institute (CSIR-SARI) and Radiation Entomology and Pest Management Centre – Biotechnology and Nuclear Agriculture Research Institute (BNARI), have revealed that the neem-based biopesticides Ozoneem and especially Grow-Safe are ‘as good as’ the insecticide emamectin benzoate in fighting the devastating Fall armyworm (FAW) pest in Ghana.
Dr Dirk Babendreier and Dr Lakpo Koku Agboyi, lead authors of the study published in Insects, considered more sustainable approaches to managing FAW – other than relying on more potentially-harmful pesticides – as part of an Integrated Pest Management (IPM) plan for farmers to help protect their maize crops.
The researchers reported on field trials that tested the effectiveness and associated cost benefits of using maltodextrin, neem-based products, ash and soil, as well as the locally produced soap alata samina – set against the control insecticide emamectin benzoate – in the Upper West and Greater Accra regions of Ghana.
Dr Babendreier and Dr Agboyi, along with their colleagues including, Dr Jerry Nboyine, Dr Michael Osae and Mr Patrick Beseh, working from SARI, BNARI and PPRSD, respectively in Ghana found that significant reduction of larval numbers of the FAW and crop damage, together with increased yields, were mostly achieved by applying emamectin benzoate.
However, while high efficiency and cost benefit ratios were also achieved with the two neem-based products, maltodextrin was only efficient at one of the two sites with a clear dose-depending effect and the higher dosage nearly as effective as emamectin benzoate. Due to the relatively high product cost, the scientists say maltodextrin was generally less cost efficient.
They add that ash and soil, as well as alata samina soap treatments, at the dosages tested, were not efficient in reducing FAW larval numbers and crop damage and as such were not beneficial in increasing maize yields. In addition, SARI and BNARI which hosted the trials reported that soil/ash are laborious to use in FAW control therefore only practical in a very small/limited scale.
Dr Babendreier said, “There is a lack of research on innovative and sustainable management approaches of FAW, including local methods used by farmers in many parts of the world, despite wide agreement that there is an urgent need for those.”
The scientists highlight that farm households often use highly hazardous and/or banned products with generally no appropriate personal protective equipment. Such over reliance on insecticides, they argue, is highly problematic due to potential environmental and health risks as well as the strong capability of the FAW to quickly develop resistance.
They add that numerous applications of insecticides are increasing production costs and, in particular, the often-used broad-spectrum products may disrupt current production systems of small holder farmers which are often based on low inputs and a certain reliance on natural biological control.
Dr Agboyi said, “The shift to applying exclusively pesticides is not in line with Integrated Pest Management approaches and is unsustainable in the long run. While we tested only a small number of potential products/local methods, of which unfortunately a few were not shown to be effective, we believe that more research would be needed to see if soil, sand or soaps could be more beneficial if used in other ways.”