Area-Wide Management of Fruit Fly Pests

A Review of the Natural 6 Host Plants of the Anastrepha fraterculus Complex in the Americas Vicente Hernández-Ortiz*, Nancy Barradas-Juanz, and Cecilia Díaz-Castelazo CONTENTS 6.1 Introduction ............................................................................................................................90 6.2 Methods and Analysis ............................................................................................................ 91 6.3 Results ..................................................................................................................................... 91 6.3.1 Diversity of Host Plants .............................................................................................. 91 6.3.2 Host Origin ............................................................................................................... 109 6.3.3 Geographical Distribution ........................................................................................ 111 6.4 Remarks and Conclusions ..................................................................................................... 113 Acknowledgments .......................................................................................................................... 114 References ...................................................................................................................................... 114 Abstract There is now enough support for the hypothesis that nominal Anastrepha fraterculus is a complex of cryptic species that are currently recognized, using morphometric procedures, as eight morphotypes that probably correspond to different biological species. In addition to this variability, there is also evidence that this nominal species presents important variation in its range of preferential host use. The aim of this chapter is to provide a comprehensive understanding of the natural host plants used by the nominal A. fraterculus under natural field conditions. This was accomplished through a bibliographic examination of information from the original sources of host plants recorded for this fly species. A total of 200 references from all regions of the Americas were examined. Data useful to the analysis were captured in a database incorporat- ing information pertaining to host identity, original source of data, and location of distribution, where available. The list of host plants for the A. fraterculus complex comprised 177 species belonging to 40 plant families, which together accounted for 1,622 documented reports. The most highly represented families were Myrtaceae (27.1%), Rosaceae (11.9%), and Rutaceae (8.5%). The Myrtaceae exhibited a high percentage (>90%) of native species in contrast to the higher proportions of exotic species presented in the other families. Guava was the only common host shared by different populations throughout the tropical and subtropical landscapes of the Americas. The highest number of hosts was recorded in Brazil (121), followed by Argentina (40), Ecuador (40), Colombia (38), Venezuela (24), and Mexico (19). The landscapes occupied by different populations of this nominal species presented some preferential patterns in terms * Corresponding author. 89 90 Area-Wide Management of Fruit Fly Pests of resource use. This reinforces the hypothesis of distinct taxonomic entities because most of the plants are present throughout the range but are not found to be common hosts to all of the fly populations. In this context, the potential application of the sterile insect technique (SIT) in certain geographical areas requires knowledge of the particular hosts consumed by the target species. 6.1 INTRODUCTION The South American fruit fly (SAFF), Anastrepha fraterculus (Wiedemann, 1830), is widely dis- tributed throughout the Americas; from the southern United States (Texas), through Mexico, Central America and South America to Argentina (Hernández-Ortiz & Aluja 1993). Based on previous research under different approaches, including the use of karyotypes, molecular DNA sequences, reproductive isolation, pheromone profiles, or even integrative approaches (reviewed in Selivon et al. 2004, 2005a, 2005b, Vera et al. 2006, Cáceres et al. 2009, Vaníčková et al. 2015, Dias et al. 2016, and others), there is now enough support for the hypothesis that this nominal species in fact comprises a complex of cryptic species that are currently recognized using morphometric procedures as eight morphotypes, most likely corresponding to different biological species (Hernández- Ortiz et al. 2004, 2012, 2015). There is also evidence that some populations exhibit important differences in the host range used, using preferential hosts at the regional scale. Moreover, their pest status can differ depending on the geographical area in which they occur; for instance, Baker et al. (1944) showed that citrus fruits such as oranges were unsuitable hosts for Mexican SAFF females and Aluja et al. (2003a) later confirmed that fruits of Citrus sinensis and Citrus paradisi in Mexico are not infested, either in the field or under laboratory-induced conditions. In contrast, studies in South America revealed that citrus fruits are common hosts for Brazilian populations of the SAFF (Malavasi et al. 1980, Zucchi 2007, and others). In this regard, there are some highly questionable reports indicating that A. fraterculus is able to infest citrus fruits in Guatemala (Eskafi & Cunningham 1987, Eskafi 1990). This variation in the range of host plants consumed in different regions of the neotropics presents a problem in terms of enforcing effective quarantine procedures. Historical accounts indicate that nearly 150 plant species host larvae feeding on their fruits across the Americas (Norrbom 2004). However, many of these records were derived from observations under laboratory conditions or copied from previous literature reports, and some fail to specify an explicit location, or even country, or there is some uncertainty regarding the fly or host plant identity. Various studies at the regional level provide information on the population dynamics of the SAFF derived from specimens caught in traps baited with food attractants. These traps are usually hung on fruit trees of commercial importance; however, this does not necessarily demonstrate that these fly larvae infest such fruits under natural conditions. This information has led to the identificationof three key problems of the phytosanitary measures that must be applied: (1) the presence of erroneous records featuring wrongly identified or unconfirmed hosts; (2) misidentification of the taxonomic species because other wild fly species are also attracted to the food baits; and (3) misinterpretation of distribution patterns based on records with inaccurate locations. As a consequence, implementation of quarantine measures and methods of integrated pest management (IPM) based on such erroneous or ambiguous information can lead to poor planning of control strategies based on concepts of fly-free or low prevalence areas, or even the application of the sterile insect technique (SIT) in specific geographical areas, which requires accurate identification of the hosts consumed by the target species. This study therefore aims to provide a comprehensive understanding of the host plants used as natural food resources by A. fraterculus. The review focuses particularly on records produced under field conditions to conduct an analysis of botanical families and host species using current botanical nomen- clature and homogenizing past and current species names, as well as examining their occurrence in different countries using the information available in the literature produced over nearly a century. This is a critical first step to elucidate the host range of the SAFF across several regions of the neotropics. A Review of the Natural Host Plants of the Anastrepha fraterculus Complex in the Americas 91 6.2 METHODS AND ANALYSIS Information was sought in the original published sources of recorded host plants of the nominal species A. fraterculus. The search was largely conducted in articles published in scientific journals, books, and unpublished dissertations available online. The main requirements of credibility for each record were inclusion of the full identity of the host plant, as well as the occurrence of fruit infestation under natural conditions in the field, with no ambiguity regarding the recorded location (to country level at least). We therefore excluded doubtful reports, those obtained under laboratory conditions, and those in which the accurate identity of the fruit fly species could not be verified. Nearly 170 references as primary sources of information from all regions of the Americas were examined. All information useful for the analysis was captured in a database, including the host identity, botanical family, original source of data, country, state or province, locality, coordinates and collection date, where available. If a single publication reported the same host in several locations, each report was considered a separate record in the database. Furthermore, each host plant was classified as native or exotic based on its origin because many were species that had been intro- duced to the Americas. A few records were omitted from the analysis, even though they were obtained under natural conditions. This was the case of two historical records for Annona cherimola Mill. in Arica (Chile) because A. fraterculus does not occur in that country since its eradication in 1964.

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