Assessment of the impact of the release of predatory mites (Phytoseiidae) on citrus and vegetables for biological control of arthropod pests: monitoring using molecular markers

Abstract

Brazilian citrus farming, which holds global leadership, has stood out for promoting socioeconomic growth, contributing to the national trade balance and, mainly, as a direct and indirect generator of jobs in rural areas. Some pests are economically important because they are vectors of pathogens in citrus, such as Diaphorina citri (HBL) and Brevipalpus yothersi (CiLV-C). Vegetable agribusiness allows the generation of a large number of jobs, especially in the primary sector, due to the high demand for labor in the various stages of production, including sowing, cultural treatments, harvesting, processing and marketing. This production chain is quite dynamic and presents several challenges, where there is year-round production in different regions of the country, with different levels of technology, productivity and cash flow for investment. In vegetables, one of the biggest challenges is the management of viruses transmitted by thrips (Frankliniella spp.) and whiteflies (Bemisia tabaci). In both cases, disease control mainly consists of eliminating vectors using agrochemicals. The use of Phytoseiidae predatory mites represents one of the most promising strategies for pest control in commercial fruit, vegetable and ornamental production systems. In addition to direct predation, the simple presence of the predator can alter the behavior of the pest, potentially reducing its damage. In the case of insect and mite vectors, the presence of predators (and associated odors) can affect their performance in the acquisition and transmission of diseases (e.g. viruses). However, the application of non-selective chemicals (e.g. insecticides, acaricides) to these crops can drastically affect predator populations. The use of strains of predators resistant (or tolerant) to compounds with a broad spectrum of action can enable the use of these natural enemies for biological control, in crops where the farmer makes frequent applications of agrochemicals. The introduction of special species and/or lineages into biological systems always needs to be monitored. The objective of this research is to monitor the establishment and dispersion of resistant populations of predatory mites introduced in citrus and vegetable crops, as well as to study the trophic chain between the species involved, in order to evaluate the impact of predators on atrophic pests ( and transmitted diseases) and other organisms (e.g. natural enemies) present in these agroecosystems. The proposed work includes the use of molecular markers to analyze the spatial reach of populations released into agricultural crops and also the gene flow between these and native populations, with possible dilution of the characters of interest (resistance to agrochemicals). In the same way, the trophic chain will be analyzed, seeking to understand the food preferences of the released predators. The behavioral changes of phytophagous arthropods in the presence of predator signals will also be studied through the analysis of volatile organic compounds (VOCs) involved in the tritrophic relationships between plant, pest and predator. The results of these studies can provide relevant information for defining vector management strategies, aiming to reduce the damage caused by transmitted diseases. (AU)