This is the first survey of frugivorous Tephritidae species in the Brazilian Chaco. Only four species of the genus Anastrepha Schiner 1868 were caught, showing the richness of the well-known fruit flies in the Brazilian Chaco, with low richness compared to other surveys carried out in different environments, mainly those in large plains that make connections, such as the Pantanal (Taira et al. 2013; Nicácio and Uchoa 2011; Uchoa and Nicácio 2010; Minzão and Uchoa 2008; Uchoa et al. 2002), among others the Cerrado (Uchoa and Bomfim 2017; Bomfim et al. 2014; Taira et al. 2013; Querino et al. 2014). Regarding endophagous tephritids associated with Asteraceae, species richness is also low (Uchôa et al. 2021).
The species caught have all been cataloged for the Pantanal Biome, such as A. fraterculus, A. sororcula, A. undosa e A. daciformis. Among these, are A. fraterculus and A. sororcula, with high pest status for Brazilian fruit production (Canesin and Uchoa, 2007). In addition to its wide geographic distribution with the generalization of a large host range and high infestation rate (Zucchi and Moraes, 2008). Although, it is important to know the occurrence of fruit flies in their host’s fruit at this location. Anastrepha undosa has a geographical distribution restricted to Mato Grosso do Sul, Minas Gerais (Nicácio and Uchôa 2010), and Tocantins (Zucchi and Moraes 2021), and only one host, Pouteria glomerata (Sapotaceae) (Nicácio and Uchôa 2010) and in Paraguay (Clavijo et al. 2020). However, the host plant has a wider geographic distribution, occurring from South America to Mexico (Bortolotto et al. 2021). The Chaco can be considered a repository area for A. undosa in the state of Mato Grosso do Sul. The level of richness and abundance represented is low, probably due to the low host frequency with fruiting seasonality (Minzão and Uchoa 2008).
Thus, for these parameters to be at high levels, it may only need to increase the occurrence of their hosts and fruiting biomass. Because, in all other environments connected by some territory to the Chaco (Amazon, Cerrado, and Pantanal), greater richness and abundance in fruit fly species have been reported (Uchoa et al. 2003; Uchoa and Nicácio, 2010; Trindade and Uchoa 2011; Almeida et al. 2016).
Non-impacted native biome environments have greater richness and less abundance compared to areas of orchards formed by mono-crops, as these provide biotic and abiotic resources suitable for the development and ecological balance of the community of these flies (Bomfim et al. 2007, Vargas et al. 2019).
As the diversity of fruit species in ecosystems increases, the diversity of fruit fly species tends to increase. Surveys carried out in the Cerrado showed richness and abundance 87% higher than that found herein (Uchoa et al. 2002; Uchoa et al. 2003; Uchoa and Bomfim 2017). Higher richness values were also observed in fruit fly surveys in Caatinga-Cerrado transition areas (Querino et al. 2014).
The Chaco has a natural barrier for propagation in the short term, which is the Serra da Bodoquena National Park between this environment and the Mato Grosso do Sul plateau (Plano de Manejo PNSB, 2013). This site is used in many places as a buffer zone used for fruit crops (Almeida et al., 2019). Therefore, in biome reserves with preservation levels higher than those of the fragments evaluated in this survey, the richness and abundance of fruit flies were also higher than those in the present study (e.g. Canesin and Uchoa 2007; Bomfim et al. 2007), in which only four species were found (Table 1).
The Chaco area surrounding these areas assessed as Biomeed Steppic Savana has been impacted by debiomeation, and agriculture and livestock production, as the main economic activity in Porto Murtinho (Pott et al. 2011). Livestock has contributed to environmental degradation in the Chaco, as increasingly larger areas are needed for grazing, resulting in the debiomeation of native flora with the consequent reduction in the number of fruit trees that host fruit flies (Pott et al 2011). This can provide an ease of movement for these insects and reach levels of infestation causing damage in future orchards of these areas if not monitored with preventive measures with MIP (Integrated pest management) methods.
The PSS area presented the greatest abundance of flies, which may be influenced by the use of fire in grasslands to renew pastures in extensive cattle-raising areas in this region (Cardoso et al., 2003). These factors probably contributed to the significantly greater abundance (n = 20) of fruit flies in that area, Park Steppe Savanna (PSS), and this effect has already been observed in Cerrado areas by Uchoa and Bomfim 2017. The richness of Anastrepha species was similar in the two phytophysiognomies: Steppic Scrub Savanna (SSS) and Biomeed Steppic Savanna (FSS), in both there were three species. This is because it is in preserved areas.
Therefore, the low diversity of Anastrepha species reported here can be explained by the environmental impacts in the surroundings and interior of the evaluated areas, especially in the Cachoeira do Apa Municipal Park, FSS (Table 2). In an environmental assessment, authors pointed out numerous deficiencies of this conservation area, directly linked to a lack of management and poor management. These factors corroborate the depreciation of environmental diversity (Veroneze et al. 2014). In addition to natural barriers and seasonal occurrences.
Anastrepha sororcula and A. undosa occurred independently of drought and flood conditions. While the specimens A. daciformis and A. fraterculus occurred in only one of these conditions, the first occurring only in a flooded area and the second in a dry area. According to Ronchi-Teles and Silva (2005), the occurrence of Anastrepha species depends on the availability of host fruits and not on climatic factors. The Brazilian Chaco vegetation is composed of more than 50% Leguminosae, Poaceae, Asteraceae, Malvaceae, Euphorbiaceae, Apocynaceae, and Rubiaceae (Sartori et al. 2018). Except for the last three, these are plant species with greater richness of species and not preferred hosts of Anastrepha spp., which explains the low occurrence of these flies. The probability of occurrence of Anastrepha species present in this study is not influenced by the dry and flooded conditions in the environment, but due by the availability of host fruits, as the species occur in both conditions.
A. sororcula and A. fraterculus are highly polyphagous, with a wide geographic distribution of their host plants throughout the Brazilian states (Uchoa and Nicácio 2010). In the state of Mato Grosso do Sul, they are the most frequent and abundant fruit fly species in Pantanal and Cerrado environments. A. sororcula and A. undosa are associated with the Chaco, in which A. sororcula has generalist foraging habits and a high level of infestation, as described by Nicácio and Uchoa (2011). On the other hand, A. undosa is characterized as a monophagous species. This species showed restricted occurrence in the environment of areas of the Pantanal.
The dispersion of fruit flies depends on the distribution density of native vegetation plants in biome fragments, serving as maintenance reservoirs for the species, such as alternative hosts, having a favorable climate for reproduction and protection against predators (Vargas et al., 2019). Therefore, vegetation with difficult-to-access density, that is, difficult to enter into the biome, has a higher probability of occurrence of Anastrepha spp. Interior areas have a greater diversity of host fruits, providing the predator with constant and alternative food (Nicholls et al. 2001). Environments with greater environmental impact are less likely to occur. The probability of occurrence of fruit flies is low in the Brazilian Chaco, however, the species collected here are very similar to those found in the Pantanal, such as the monophagous species A. undosa registered in Pouteria glomerata, with a wide distribution in the Chaco in Brazil, Bolivia and Paraguay (Pott and Pott 1994).