Evaluation of shade nets and Nuclear Polyhedrosis Virus (SeNPV) to control Spodoptera exigua (Lepidoptera: Noctuidae) on shallot in Indonesia

The beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae) is a serious pest of shallot in Indonesia. Chemical methods have failed to control this pest as this has developed resistance to almost all synthetic insecticides available. Shade nets are widely used to protect vegetables crops from pest and diseases. Field experiments were conducted during dry and rainy seasons (2012–2013) in Cirebon, West Java to assess the potential of shade nets and SeNPV for managing insect pests in shallot in order to reduce the use of pesticides. Completely randomized block design were used in this experiment with five treatments and five replications. The treatments viz. control treatments (without shade nets and SeNPV), shade nets (white and blue colors), applications of SeNPV and farmer’s practices. The data observed were plant growth, population of S. exigua, percentage of plant damage and yield. The result showed that the number of S. exigua was significantly lower with shade nets (white and blue) compared to foliar insecticide sprays (farmer’s practices). SeNPV moderately suppressed S. exigua with statistically significant efficacy over the control. Reduction in eggs and larvae of S. exigua numbers inside the shade nets ranged 98.40 to 100%. The shade nets also reduced number of pesticide applications by 100%. Furthermore, the lowest percent pest damage and the highest bulb yield were found at shade nets (white and blue) and foliar insecticide sprays. The use of shade nets in shallot production might offer several advantages. It would enable to protect shallot from S. exigua incidence, thus replacing applications of chemicals insecticides or hand picking practices. The technology is, therefore, friendly to the environment.