Thrips are considered one of the most harmful pests and their control is a serious concern for farmers in many avocado-producing areas (Seena et al. 2020). Several works have focused on investigating the diversity of Thysanoptera associated with avocado crops to determine the species related to the damages. Most of the species found in this work coincide with those reported in other studies carried out in America (Hoddle et al. 2002; Johansen-Naime et al. 2003; Valle-De la Paz et al. 2003; Cambero-Campos et al. 2011) and Africa (Odanga et al. 2017a). In accordance with our bibliographic review, Frankliniella sueoa, Caliothrips nanus, Caliothrips insularis and Charassothrips incomparbilis are recorded for the first time associated with avocado crops. Frankliniella sueoa has only been previously reported associated with Aegiphylla panamensis flowers in Costa Rica (Mound and Marullo 1996). Caliothrips nanus and C. insularis were reported associated with grasses (Poaceae) and Glyciridia sepium (Fabaceae) in Panama (Goldarazena et al. 2012). These two species were also recorded associated with mountain cloud forest vegetation in Chiapas, Mexico (Goldarazena et al. 2014). Other Caliothrips species such as C. phaseoli, C. punctipennis and C. fasciculatus has been found in avocado trees in Michoacán, México (Valle-De la Paz et al. 2003; Johansen and Mojica 2007; Hoddle et al. 2002). Charassothrips incomparbilis was originally collected on mosses and lichens growing on tree trunks in mountain cloud forest and in inflorescences of Piper auritum and P. aduncum in México (Johansen 1986; Mound and Marullo 1996). The highest abundance of thrips was observed in the flowering and fruiting months in both orchards and coincides with the population peaks of F. gardeniae. This population pattern has been observed with this species in mango crops where the specimens migrate to other hosts, such as nearby weeds at the end of flowering (Sierra-Baquero et al. 2018). It is known that F. gardeniae prefers young tissues such as floral organs, leaf buds and newly formed fruits (de Oliveira et al. 2011) therefore, its population decreases naturally in avocado crops after the flowering season and the first stage of fruiting. It is likely that F. gardeniae specimens migrate to other host plants during the absence of adequate food in avocado trees in the months of May to November, however, studies need to be conducted in this regard.
In the main avocado producing regions of the world such as the state of Michoacán in México and California in the United States, Scirtothrips perseae is considered the main species of pest thrips and is responsible for the damage caused to the fruits, therefore, research and management efforts have focused on this species (Hoddle et al. 2003; Tzec-Interián et al. 2020). However, this contrasts with the results of this study, where S. perseae is found in very low populations and the most abundant species is F. gardeniae. The high valleys of Mexico and Central America are considered the center of origin of S. perseae and its known distribution is limited to areas with the presence of avocado plants and their surroundings (Hoddle et al. 2002). On the contrary, F. gardeniae is a polyphagous species widely distributed in the American continent, it has been reported in association with the flowering of various agricultural crops, aromatic plants and weed flowers (Cavalleri and Mound 2012; Rodríguez-Arrieta et al. 2023). Frankliniella gardeniae is considered an important pollinator species on mango crops (Mangifera indica L.) in Costa Rica (Retana-Salazar and Rodríguez-Arrieta 2015). Likewise, in Colombia it is the most distributed and abundant species in avocado, coffee, citrus and mango (Ebratt-Ravelo et al. 2019; Cano-Calle et al. 2021). This species is also associated with damage to vineyards fruits (Vitis vinífera L. cv. Sugraone) in Brazil (Moreira et al. 2014) and to flowers, fruits and leaf buds in avocado crops in Colombia (Echeverri et al. 2004).
In México, F. gardeniae had not been considered an important species in avocado crops due to its low abundance and was classified as a visitor species (Cambero-Campos et al. 2011). However, and coincident with the present study, in recent years important populations of this species have been detected in avocado crops; in collections carried out in Michoacán it was the third most abundant species, below S. perseae and F. occidentalis (Bravo-Pérez et al. 2018) and in collections carried out in the Veracruz state it was the most abundant species with 62.6% (López-Lima et al. 2020). It is possible that polyphagous populations of F. gardeniae have different feeding options within orchards throughout the year, displacing S. perseae populations that have a limited host range and is located outside of its origin area. Furthermore, because control efforts are always directed at the foliage of avocado trees, F. gardeniae specimens are less exposed to insecticide applications or massive trapping by taking refuge in other plants, but this must be studied.
Another species with habits like F. gardeniae is Frankliniella shultzei. This species is considered one of the main pests in avocado crops in Kenya and Tanzania, causing flower drop and reduced fruit set (Odanga et al. 2017b). It is possible that high populations of F. gardeniae are causing damage in the orchards studied, as occurs in Colombia with this same species and in Africa with F. shultzei, however, the role of F. gardeniae in the avocado orchards in México must be studied.
Due to the economic importance of the Hass avocado in México and the increase in the surface area destined to produce avocados in other states such as Veracruz, the prevention of damage caused by thrips is essential to ensure the aesthetic quality of the production, mainly that destined to export. Derived from the results of this research, it is recommended to start with control strategies in the months of November and December before the beginning of flowering to avoid the increase in populations in the months of February, March and April, critical stages where the thrips can affect fruit setting and injure newly formed fruits. Likewise, we consider the importance of carrying out detailed studies on the weeds present in the avocado crop, which could serve as a food source or shelter for polyphagous thrips species during the months of low food availability in the avocado trees.