Invasion and Spreading of Drosophila nasuta (Diptera, Drosophilidae) in the Caatinga Biome, Brazil

Drosophila nasuta (Diptera, Drosophilidae) in Brazil: a decade of invasion and occupation of more than half of the country

As a result of human activities and natural dispersal, exotic species can be brought to new areas, where they become established and spread, becoming invaders. These species are responsible for the loss of biodiversity and cause ecosystemic harm throughout the world. In this paper, we report the rapid, broad geographic expansion of the invasive fly Drosophila nasuta in Brazil. An 84% increase was found in its area of occupation in the country compared to previous studies. The present data reveal its arrival to the Pantanal wetlands in a location more than one thousand kilometers from the closest previous record in the Cerrado biome. We present the first record of D. nasuta in the Atlantic Forest in the states of Paraíba and Bahia. We report its introduction in the Amazon Forest in the state of Amazonas approximately 700 kilometers from previous records. The relative abundance of D. nasuta in this biome increased fivefold in comparison to a previous study. In the first decade of invasion in Brazil, D. nasuta has already colonized more than half of the country. The present data reveal its invasive potential and underscore the importance of following up the possible negative effects of this biological invasion.

Establishment and Expansion Scenario of Drosophila suzukii (Diptera: Drosophilidae) in Central Brazil

Drosophila suzukii Matsumura (Diptera: Drosophilidae), also known as spotted wing drosophila (SWD), is an important pest that damages various wild and cultivated soft fruits worldwide, especially in the Northern Hemisphere. In Brazil, it occurs mainly in the subtropical climates of the southern and southeastern regions. However, SWD has also been sporadically found in the central region of the country in the natural vegetation of the tropical Brazilian Savanna. In this study, we investigated the occurrence of SWD at the northern limit of its range in South America - the central region of Brazil - by monitoring an established drosophilid community in an orchard located in the Brazilian Federal District. We also investigated the current geographical distribution of this pest in Brazil and its potential geographical distribution using species distribution models under two different future shared socioeconomic pathways scenarios (2040 and 2060, optimist and pessimist). Twenty drosophilid species were detected among the 6,396 captured specimens, most of which are exotic in the Neotropical region. The fly community greatly fluctuated throughout the year, and the highest abundance of SWD (3.5% relative abundance and 1.38 flies/trap/day) was recorded in April during the rainy season. Potential distribution models indicate that suitable areas for SWD spread will decrease in the south and southeast but increase in the central region of Brazil. We recommend continuous SWD monitoring and improving bioclimatic forecast models for mitigating damage to local fruit production.

Host Preferences Shown by Drosophilids (Diptera) in a Commercial Fruit and Vegetable Distribution Center Follow the Wild Neotropical Pattern

Although drosophilids have been extensively studied in laboratories worldwide, their ecology is still relatively poorly understood. This is unfortunate because some species are currently expanding their geographic distribution and infesting fruit crops. Here, we investigated the relationship between drosophilids and potential plant hosts in a commercial fruit and vegetable distribution center in the Neotropical region. We collected discarded fruits and vegetables from this commercial center during two time periods (2007-2008 and 2017-2018). Resources were weighted and individually monitored in the laboratory. The drosophilids that emerged were identified, and the relationship between them and their resources was explored. From the 99,478 kg of potential hosts collected, we identified 48 plant taxa, from which 48,894 drosophilids of 16 species emerged. On both collecting occasions, drosophilid assemblages were strongly dominated by basically the same exotic species, which explore a broader range of resources, especially those of exotic origin, when compared to neotropical drosophilids. These results are concerning because the studied site, Along with other urban markets around the world, might be acting as sources of generalist widespread species that disperse to surrounding natural vegetation and contribute to biotic homogenization.

First Records of the Invading Species Drosophila Nasuta (Diptera: Drosophilidae) in the Amazon

Invading species pose a growing threat to biodiversity, ecosystemic systems, regional economies, and public health. In recent decades, South America has received five exotic drosophilids species, some of which have invaded natural ecosystems and caused harm to agriculture. The most recent case is the Asian fly Drosophila nasuta Lamb. In the present study, we record D. nasuta in the Amazon, which is the largest and most biodiverse tropical rainforest in the world. Sampling of drosophilids was carried out between 2012 and 2017 in the Brazilian state of Pará. Drosophila nasuta was first detected on 1^st July 2017, with 145 individuals of this species sampled among the 11,496 drosophilids caught. Although at low abundance, D. nasuta was recorded in forest fragments, anthropized fields, and urban environment. The records of the species occurred in the six municipalities of the state of Pará investigated at locations separated by approximately 700 km. In less than 10 years, D. nasuta has occupied approximately 2.5 million km² in South America. The present findings assist in understanding the susceptibility of tropical forests to biological invasions.

Current and future potential global distribution of the invading species Drosophila nasuta (Diptera: Drosophilidae)

Species distribution modelling has been widely employed to indicate probable areas of invasion and to guide management strategies. Drosophila nasuta is native to Asia and has invaded Africa, islands of the Indian and Pacific Oceans and, more recently, the Americas. This species has been dispersing rapidly in the past decade, dominating the assemblage of drosophilids in numerous invaded territories, especially in protected areas. Here, we model the potential geographic distribution of D. nasuta for the present and two future scenarios. We also determine the environmental variables that most influence its distribution and investigate the risk of invasion in protected areas. Drosophila nasuta has the potential to expand its occurrence, especially on continents that have already been invaded. Variables related to greater rainfall were those that most influenced its distribution. The projections for the two future scenarios revealed a small increase in the distribution of the species compared to the projection for the present. The largest overlaps between the projected areas to be invaded by D. nasuta and territories in protected areas were found for Central and South America. The predictive maps delineated here can assist in the establishment of management plans directed at the conservation of biodiversity.