Chrysodeixis chalcites, a pest of banana crops on the Canary Islands: Incidence, economic losses and current control measures

Highlights

• Chrysodeixis chalcites was present in 42–100% of surveyed banana plantations.

• Foliar and fruit damage varied significantly across islands, plantation aspect and season.

• Overall, 1.5% of the annual banana production is discarded due to C. chalcites damage, representing €2.68 million.

• Indoxacarb is the most frequently used insecticide, applied 3 times per crop cycle, representing a cost of €240/ha.

• Effective and sustainable control strategies are required against this pest.

Abstract

Chrysodeixis chalcites is an emergent pest in bananas (Musa acuminata Colla) grown on the Canary Islands. Feeding damage to leaves and fruit and the control measures targeted at this pest were evaluated over a two-year period (2013–2014). The prevalence of infestations (42–100%) on the islands was similar during the two years of the study. Mean foliar damage (1.5–7.3% depending on island) and fruit damage (1.0–5.7%) detected in field surveys varied significantly across islands, plantation aspect (north- or south-facing) and season. Fruit damage was not correlated with foliar damage (P > 0.05). The weight of C. chalcites damaged bananas varied significantly (0.2–4.2% of harvested fruit) across islands, particularly in the spring. Overall, 3155 tonnes of bananas/yr are likely discarded due to C. chalcites damage, representing 1.5% of annual production or 2.68 million €/yr. The most frequently used pesticide was indoxacarb, usually applied on three occasions per crop cycle, for which the cost of control measures would average 240 €/ha per crop cycle. The direct damage that C. chalcites causes to banana fruit results in significant economic losses in addition to the direct costs of pesticide based control measures. Effective and sustainable control strategies are required against this pest.

Introduction

Banana (Musa acuminata Colla) represents one of the most important agricultural goods with an annual trade valued at nine billion dollars worldwide (Arias et al., 2003; Hallam, 1995; Raynolds, 2003). Banana is the main crop of the Canary Islands, representing 30% of total agricultural production (González-Concepción et al., 2008; Robinson and Galán-Saúco, 2010). In 2015, this crop was grown over an area of 8975 ha (i.e., 23% of the total cultivated area of the archipelago), with a total production of 381,983 tonnes, representing 0.3% of the world's banana production. The island of Tenerife is the largest producer of bananas in the Canary Islands (43% of the total production), followed by La Palma (33%) and Gran Canaria (22%), while the remaining 2% of production occurs on the islands of La Gomera, El Hierro and Lanzarote. Most of the production is destined to markets in the Iberian Peninsula (91%), and only a small fraction is exported to Western Europe (0.1%), whereas the remainder (8.9%) is consumed locally (ASPROCAN, 2016; MAPAMA, 2016). Banana production is also of great social importance in the Canary Islands as it employs over 7000 people, representing up to 10% of jobs on some of the islands. Many other sectors also provide services to, or depend on, banana production, including the tourism sector as banana plantations have become a destination for tourist visits (Bianchi, 2004; González-Concepción et al., 2008). Bananas are cultivated in mesh-built greenhouses on the warmer southern slopes and in the open-field on the cooler, northern areas of these islands. As such, crops grown under mesh tend to be more prone to phytosanitary problems (Del Pino et al., 2011; Galán-Saúco, 1992; Robinson and Galán-Saúco, 2010).

Banana crops present numerous phytosanitary problems, with the most important and widespread pest being the banana weevil Cosmopolites sordidus (Germar) (Carval et al., 2016; Gold et al., 2001). Lepidopteran pests species, on the other hand, have a local distribution; for example, the species Antichloris viridis Druce, 1884 and Caligo memnon C. Felder & R. Felder, 1867 are present in Venezuela, Costa Rica and other countries of Latin America (Liscano and Dominguez-Gil, 2005; Smilanich and Dyer, 2012); Spodoptera litura Fabricius, 1775 and Chrysodeixis acuta Walker, 1858 are present in India (Tayade et al., 2014) and Chrysodeixis chalcites (Esper) is an important pest on banana crops only in the Canary Islands. C. chalcites also affects numerous fruit, horticultural, ornamental and forest crops such as cotton, alfalfa, cabbage, sunflower, geraniums, beans, corn, turnips, potatoes, cucumbers, peppers, bananas, soybeans, tobacco and tomato (Cabello et al., 1996; Passoa, 1995).

Chrysodeixis chalcites was previously a minor pest on the Canary Islands banana crops that caused leaf damage which did not usually justify control measures (Del Pino et al., 2011). However, since 2000, this insect has shown marked changes in its feeding behavior for unknown reasons. Specifically, larvae have begun to feed on the skin of the banana fruit causing marked aesthetic damage that completely eliminates the commercial value of the fruit (Del Pino et al., 2011; Perera and Molina, 2007). As a result of this unusual behavior, C. chalcites is now the lepidopteran pest that requires the greatest number of insecticide treatments and control costs appear to be increasing over time (Del Pino et al., 2011; Domínguez et al., 2012).

Although C. chalcites larvae are known to seriously affect the saleable yield of banana (Del Pino et al., 2011; Perera and Molina, 2007), accurate estimates of pest-induced losses are not available. Determining the production losses and economic impact caused by this pest in banana crops in the Canary Islands is necessary for pest control decision-making. Pest population assessment is one of the fundamental aspects used to determine the need to use pest control interventions in Integrated Pest Management (IPM) programs. Since 2014, an IPM approach is mandatory in all crop production systems in Spain (Royal Decree 1311/2012, which incorporates European Directive, 2009/128/EEC that established a framework for the sustainable use of pesticides in the European Union). Effective decision-making in IPM also relies on understanding the relationships between pest numbers, plant responses to injury and the resultant economic losses (Higley and Pedigo, 1993; Pedigo, 1996).

The objective of the present study was to evaluate the incidence and feeding damage inflicted by C. chalcites as well as to estimate the production losses and economic impact of this pest on banana crops in the Canary Islands. We also aimed to estimate losses arising from direct damage to fruit and indirect costs involved in the purchase and application of insecticides targeted at this insect. The results of the present study are part of a wider approach to define C. chalcites damage thresholds in banana crops and the potential use of novel biological insecticides that are currently under development (Bernal et al., 2013; Simón et al., 2015).