Interaction between the incidence of Prodiplosis longifila Gagné (Diptera: Cecidomyiidae) and management practices in tomato crops in Manabí, Ecuador

Abstract

Tomato (Solanum lycopersicum L.) is a vegetable in high demand, since its consumption is associated with its important nutritional properties (Arroyo et al., 2018), therefore its cultivation has increased worldwide (Trust Funds for Agricultural Development [FIRA], 2017). In Ecuador, 91 % of the production areas are located in the provinces of Imbabura, Manabí, Pichincha, Carchi, Cotopaxi, Azuay, and Chimborazo. In Manabí, in 2021, 35 ha were established with a production of 319 t and an average yield of 9.02 t.ha-1 (Agricultural Public Information System [SIPA], 2021). In Ecuador, Prodiplosis longifila Gagné (Diptera: Cecidomyiidae) constitutes the main pest of economic importance of the tomato crops, limiting production and profitability of the crop, since the costs for its control represent up to 50 % of the total production cost (Cañarte et al., 2015; Polo, 2017). The damage of P. longifila is caused by its larva in the first instars (Cardona et al., 2010), with losses of up to 100 % of production (Cañarte et al., 2015). In the flower, it affects the epidermal cells of the ovary, pistils, and stamens (Peña and Mead, 2016). The female oviposits on the plant epidermis, without perforating the tissues, in protected areas such as closed buds, flower buds, and at the base of the fruits (Díaz, 2011), where upon hatching, the newly emerged larvae feed on these tender tissues, scraping the surface of the bundle, whose damage turns it blackish and in young fruits causes necrotic scars that deform the base, taking away its commercial value (Geraud et al., 2022). The biological cycle of P. longifila is 11 to 24 days, distributed in three larval instars (2-3 days), pre-pupa (2-3 days), pupa (6-7 days) and adult (1-2 days), except for certain field or laboratory variations (Valarezo et al., 2003; Díaz, 2011; Geraud et al., 2022). It is a multivoltine species, which develops 18 to 22 generations per year, depending on environmental conditions of temperature, relative humidity and precipitation (Díaz, 2011). The control of P. longifila is almost exclusively chemical, with extremely toxic insecticides, such as metamidophos (Valarezo et al., 2003; Polo, 2017; Chirinos et al., 2020), triazophos (Fernández, 2016), benfucarb (Polo, 2017), methomyl (Polo, 2017; Chirinos et al., 2020) applied during the crop cycle, including the harvest stage. The use of this type of insecticides generates environmental pollution and ecological imbalance (Hernández et al., 2015), affecting human health (Lindao et al., 2017), which affects the quality of life of the producer (Bravo et al., 2020). In view of this situation, the implementation of sustainable integrated management programs should be considered, which include: 1) biological control through the action of predators, parasitoids and pathogens (Díaz, 2011; Cedano and Cubas, 2012), 2) genetic control with the use of cultivars that are harmless to the attack of P. longifila (Mena et al., 2014), 3) cultural control (Cañarte et al., 2015), 4) ethological (Camborda et al., 2015), in order to reduce or eliminate insecticide applications, which are responsible for the increased incidence of this species as a tomato pest, due to the elimination in the field of one of its natural biological controllers (Synopeas sp.), which was reported by Geraud et al. (2022) parasitizing the larvae of P. longifila in the tomato crop in Ecuador. Consequently, the objective of this research was to determine the interaction between the incidence of the pest and the agronomic and phytosanitary practices applied by producers in tomato crops in six cantons of the province of Manabí, Ecuador.