Eco-friendly application of vermiwash obtained from different types of waste with neem seed kernel extract against papaya mealybug, Paracoccus marginatus Williams and Granara de Willink

The concern of organic farming and sustainable agriculture has increased in recent years. Unrestrained applications of fertilisers and pesticides in agriculture have caused adverse effect on the environment [1]. Meanwhile the rate of solid waste generation is escalating with population increase and industrialisation [2]. Improper management of bio solid waste cause serious problems in the society [3]. Vermicomposting is one of the environmental friendly methods in converting various bio wastes through earthworms into vermicompost and vermiwash [4]. These eco-friendly products can be an alternative to agro-chemicals. Vermiwash is a brownish-red liquid extract collected after the passage of water through a column of vermiculture. It is a collection of coelomic fluid and excretory products of the earthworms. The liquid fertiliser vermiwash helps to enhance crop productivity. Besides, it is effective against pests and diseases [5]. Vermiwash is rich in several nutrients, vitamins and plant growth regulators [6]. It also comprises insecticidal and antifungal bioactive compounds which suppress pest and diseases [7]. Earthworms express coelomic fluid when under severe stress condition. The coelomic fluid of the earthworm is secreted through dorsal pores in the form of mucus as a response of defense mechanism. The biological activity of the earthworm depends on the type of waste material provided as the feed for vermicomposting. The performance of Eisenia foetida varies indifferent types of waste used for vermicuture [8]. A number of studies have been undertaken on vermiwash as a liquid fertiliser in many crops. However, the study on application of vermiwash obtained from different types of waste in pest management is scarce. There are various number of plant based pesticides used to manage the pests inorganic farming. Neem (Azadirachta indica A. Juss) has remarkable insecticidal properties [9]. Azadirachtin is a component of neem which is an effective plant based pesticide and also has antifeedant and toxic effects on insects [10, 11]. In this study neem seed kernel extract was selected as a plant based pesticide to combine with vermiwash to manage soft body insects in papaya cultivation. Papaya mealybug (Paracoccus marginatus Williams and Granara de Willink) of order Hemiptera, family Pseudococcidae is a severe pest of Carica papaya [12]. It is an invasive pest to Sri Lanka; it was first reported in Colombo and Gampaha districts in July 2008 [13]. It is a pest in fruit and vegetable crops and ornamental plants. It has avery wide host range extending up to 22 families of plants in Asia [14]. The insect feeds on leaves, stems and fruits and sucks the sap causing stunting of the plants, chlorosis, early fruit drop and death. Sooty mould is formed by the honeydew secreted by the insects while feeding [15]. There were many natural enemies of papaya mealybug recorded in the field. Insect like green lacewing (Chrysoperla carnea Stephens-Neuroptera: Chrysopidae) and coccinellid beetle (Anegleis cardoni Weise) and a spider species (Phintella vittata-Arachnida: Araneae: Salticidae) were recorded to predate on papaya mealybugs [16, 17]. Frequent and excess use of chemical insecticides results in depletion of natural enemies [18]. Thus, there is a need to use alternative environmental friendly insecticides to sustain the management. The objective of the study is to test the effect of different types of vermiwash and neem seed kernel extract on papaya mealybugs and its predators on Carica papaya as an environmental friendly solution.