Ex-ante Economic Analysis of Biological Control of Coconut Mite in Benin

Introduction Coconut (Cocos nucifera Beccari) is the main source of cash income for farmers in the coastal belt of Benin. Oleke, Manyong, Hanna, and Isinika (2010) reported that coconut contributes about 56% of the total head of household cash income among coconut farmers in Benin, equivalent to US$4001 of the total rural household cash income. Additionally, coconut juice serves as an important supply of fluids and minerals. The oilcake remaining after oil is pressed from copra is used as animal feed (Woodroof, 1970). The coconut shell is used directly as fuel, filler, and extender in the synthesis of plastic and for making household articles. In the coastal belt of Benin, different parts of the coconut plant (truck and leaves) are widely used as building materials, and in recent years the coconut palm wood has been used to make high-quality furniture for the local and export market. The coconut, like many plants, is subject to attack by various pests and diseases. The coconut mite, Aceria guerreronis Keifer, has been identified among common coconut pests of economic importance. The coconut mite breeds under the perianth (the outer part of the flower consisting of the calyx and corolla, and enclosing the stamen and pistils) of coconuts, where it feeds on the epidermal cells of the meristematic region. Occasionally it feeds on the apical meristem of the coconut seedling. In severe infestations, reduction in nut size and malformation of nuts occur. Consequently, farmers incur economic losses due to the continued presence of pest. The coconut mite is therefore one of the leading exotic pests that pose a threat to the coconut industry in countries such as Benin, Tanzania, India, and Sri Lanka. The coconut mite has proven to be difficult to control. A wide range of chemicals have been employed to control the pest over the past two decades, but the results have been unsatisfactory. Thus, efforts to eradicate it or minimize its damage have been expensive (Pimentel, 2000). Meanwhile, farmers continue to suffer high economic loss (Aquino & Arruda, 1967). Good plant husbandry has been recommended to alleviate the economic impact of the mite on coconut production. In the mean time, research has been directed toward identifying resistant coconut varieties and biological control agents (Pimentel, 2000). Decreases in coconut yield from mite attack cause loss of income, food insecurity, and poverty for farmers and others in the coconut value chain. A survey was carried out by the Coconut Research Institute (CRI) in Sri Lanka in 2001 to monitor harvested nuts for one year at monthly intervals. The study revealed that the percentage of mite-infested nuts in various Sri Lankan cities was 94.4% in Anuradhapura, 94.5% in Pollonnaruwa, 90.5% in Rajangane, 85.1% in Puttalam, and 69.8% in Kurunegala, with a mean of 77.9% (Peiris, 2006). In Tanzania, reduction in copra yield has been variable from 15-40% (Seguni, 2002). Elsewhere, losses due to extensive premature dropping of fruits have been reported, ranging from 60% in Colombia (Zuluaga & Sánchez, 1971) to 70% in Venezuela (Doreste, 1968) and 10-100% (average 21%) in Tanzania (Seguni, 2002). For the nuts that reach maturity, small-sized nuts 1. Unless otherwise specified, all monetary values in the article are in US dollars. Jofrey M. Oleke, Victor Manyong, and Djana Mignouna International Institute of Tropical Agriculture, Tanzania