Management of Noorda blitealis Wlk. on Moringa oleifera Lam. using biorationals in the home gardens of Jaffna district, Sri Lanka
Abstract
Moringa oleifera Lam. (Moringaceae) is one of the main crops grown for pods and leaves in Jaffna home gardens in Sri Lanka. After the introduction of Periyakulam 1 (PKM 1) Moringa, a leaf eating caterpillar (Noorda blitealis Wlk.) turned out to be a serious pest causing damage to the leaves. Considering the severity of the damage, this study was carried out to find out the suitable biorationals to manage the pest in an eco-friendly method. Using the leaf disc dipping method biorationals such as 1% neem oil, 3% neem seed kernel extract and 2.5g/L neem leaf extract were used to determine the larval mortality. Consumption of the treated leaf area was measured to determine the larval antifeedant activity for 1% neem oil, 3% neem seed kernel extract, (2.5g/L) neem leaf extract, 15% (g/mL) garlic extract and 75% fermented cow urine and ash solution. Distilled water was used as control in both experiments. The experiments were carried out at a temperature of 28.9 ± 1.13°C and 73% relative humidity in complete randomized design. On the 6th day after treatment larval mortality in 1% neem oil, 3% neem seed kernel extract and 2.5g/L neem leaf extract were 85%, 83.33% and 70% respectively. After 24 hours larvae fed with 1% neem oil, 3%neem seed kernel extract, (2.5g/L) neem leaf extract, 15% (g/mL) garlic extract and 75% fermented cow urine and ash solution showed a larval antifeedant activity of 85.51%, 84.84%, 74.18%, 76.13% and 48.16% respectively.
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Introduction
The multipurpose Moringa oleifera Lam. belongs to the Family Moringaceae which is a well-known tree grown in the home gardens in Northern Province of Sri Lanka. Leaves, pods, flowers, roots, seeds, bark and wood of the tree have nutritional, medicinal and industrial benefits [1]. Families in Jaffna districts consume the pods and leaves for their daily nutritional requirements. As the demand for the organic Moringa leaves has increased in local and foreign markets, many farmers have started to show interest in cultivating Moringa. An annual bush type, Periyakulam 1 (PKM 1) Moringa which was introduced from India is widely cultivated in resettled home gardens in the Jaffna district.
In recent years, PKM 1 Moringa crops were severely attacked by a seasonal pest Noorda blitealis Wlk. It is a leaf eating caterpillar which belongs to the Family Pyralidae. The larvae is creamy and sometimes ranges from pale green to cream or pink in colour, feeds on the Moringa leaves and in severe conditions they completely defoliate the plant. The affected leaves are skeletonized and appear as translucent sheets and finally dry up. In some conditions especially when the tree is pruned the larvae begin to feed on the stem pith and bark of the tree. In this condition they feed either on the corky content inside the stem heart or on the fleshy bark under the skin [2].
Since there is limited information regarding the pest, there were no effective management practices followed by farmers. Considering the economic status and the health issues of the resettled families and other Moringa growers in Jaffna district, this study was carried out to identify suitable techniques to manage the pest with low cost and easily available eco friendly biorationals.
Conclusion
Larvae fed with 1% neem oil, 3% neem seed kernel extract showed higher mortality percentages and strong antifeedant activity. In Jaffna home gardens compared to the chemical pesticides, neem based products are easily available and economic to suppress the pest population build-up. The demand of organic Moringa leaves in export sector has increased in recent years; therefore there is a need for good quality organic leaves in the market. Neem products such as 1% neem oil, 3% neem seed kernel extract and 2.5g/L neem leaf extract can be sprayed on the leaf surface to prevent leave damage by the larvae.
References
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