First reports of the invasive pest Bermudagrass Stem Maggot , Atherigona reversura Villeneuve , 1936 ( Diptera : Muscidae ) , in South America

This study presents the first occurrence of Atherigona reversura in South America. This muscid, commonly known as shoot-fly, is a significant pest of cereal crops throughout the Old World tropics and subtropics. Several specimens were collected during various months in 2014 and 2015. These new records are dispersed in a wide geographical area of temperate and subtropical regions of eastern Argentina. The main host of A. reversura, the exotic bermudagrass Cynodon dactylon, is considered a pest and is widely distributed in South America.

Atherigona Rondani, 1856 is a genus of Muscidae from the Old World that is widely distributed in the Afrotropical and Oriental regions.These muscids, commonly known as shoot-flies, are a significant pest of cereal crops throughout the Old World tropics and subtropics (Pont and Magpayo 1995).Atherigona is divided in two subgenera: Acritochaeta (Grimshaw, 1901), whose larvae live in decaying plant or even animal matter, and Atheri gona s. str., whose larvae are phytophagous and primary pests of various species of Poaceae (Skidmore 1985).
In the New World, only two introduced species are present: Atherigona (Acritochaeta) orientalis Schiner, 1868, with a distributional range from southern USA to northeastern Argentina (Carvalho et al. 2005), and A. (Atherigona) reversura Villeneuve, 1936, recently recorded from the North American continent (Hudson 2010).
The geographic distribution of this Oriental species included Burma, China, India, Indonesia, Malaysia, the Philippines, Sri Lanka, and Taiwan, but has now extended to the Australasian (Hawaii, Papua New Guinea), Palearctic (Japan, Oman), Nearctic (USA), and Neotropical (Mexico) regions (Table 1; Figure 1).
Here, we report the first occurrence of A. reversura in South America and its first record in Argentina.We collected this species in several localities of Buenos Aires, Santa Fe and Chaco provinces.Some of the specimens collected in Santa Fe and Chaco were associated to cultivated fields.Specimens of A. reversura were collected during two surveys of the diversity of Calyptratae in two different ecoregions: Oriental Chaco (Villa Berthet) and Pampas Grasslands (Reserva Natural Estricta (RNE) Otamendi).Flies from Villa Berthet were collected using Van Someren-Rydon canopy traps (Rydon 1964) baited with rotten squid, whereas specimens from RNE Otamendi were obtained with Malaise traps.These trapping programs were performed monthly in Villa Berthet and seasonally in RNE Otamendi.In addition, a small number of supplemental specimens of A. reversura were obtained from occasional catches with a hand net at Burzaco, Buenos Aires province and at Santa Isabel, Santa Fe province (Figure 1).These catches were obtained during July 2015 and December 2014, respectively (Table 2).We obtained the georeferences from bibliographic and internet sources (Table 1).If localities were only mentioned without coordinates in the sources, their georeferences were obtained from Google Earth™.Voucher specimens were pinned and deposited in the Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" (MACN), Buenos Aires, Argentina: MACN-En

Patitucci et al. | First record of Atherigona reversura in South America
Chaco (March 2015).The absence of collected specimens in the RNE Otamendi during the winter months (July) but their presence in areas close to Villa Berthet (June to August) is interesting to highlight.This may be because this species is active throughout the year in northeastern Argentina.
Specimens of A. reversura were collected in several sites including different kinds of habitat.These new records are dispersed in a wide geographical area of temperate and subtropical regions of eastern Argentina.This species was found inhabiting private gardens in an urbanized area and in a grassland protected area in Buenos Aires; it was also recorded in crop edges in Santa Fe province.In the case of samples from Chaco province, A. reversura was recorded in gardens of a small village (Villa Berthet) and in crops and cattle farms adjacent to this location.The fact that the co-generic species A. orientalis was also found in Villa Berthet, sharing the same habitats, is important to point out.
Specimens were identified by L. C. Patitucci (first author) using taxonomic key and descriptions provided by Pont and Magpayo (1995).Adult males and females have transparent wings, a gray thorax and a yellow abdomen with at least one pair of black spots.Males (Figure 2) can be recognized by the bicolored frontal vitta, yellow palpi and fore tarsomeres with elongated hairs and trifoliate process (Figure 3).
The first occurrence of A. reversura in Argentina was recorded in Santa Isabel (Santa Fe) in December 2014, followed by almost simultaneous records in the provinces of Buenos Aires (April and May 2015) and   subtropical areas and is now common in grasslands, lawns, pastures, roadsides, sea-coast sandy dunes, irrigated land and along rivers (Heuzé et al. 2015).In Argentina, this grass species is considered a pest and is widely distributed (SINAVIMO 2015).Damage to C. dactylon by larvae of A. reversura is frequently mistaken with stress, nutrient deficiency, bermudagrass leaf spot, and/or leaf rust, which can result in discolored plant material.Larvae of A. reversura only produce chlorosis in the top two to three leaves of the plant (Baxter et al. 2014).Recently, the Bermudagrass Stem Maggot has become a pest for cattlemen and hay producers across the USA (Hudson and Hancock 2013).Although there is no published work on the biology of adults of A. rever sura, Baxter et al. ( 2014) suggested these adult flies may feed on sugar exudates from grass.
Considering the distribution of bermudagrass in South America, establish the actual distribution of A. reversura is important because it may be being dispersed to some regions of neighboring countries with similar climates such as Brazil, Paraguay and Uruguay.Simultaneously with this report we have informed local authorities.

Figure 1 .
Figure 1.Geographic distribution of Atherigona reversura in the world.Orange circle: new records; yellow square: known record georeferenced (bibliographic source); blue square: known record georeferenced (internet source); red area: known record not georeferenced (countries/province/states) (see

Table 1 .
Known records of A. reversura in the world.Latitude and longitude are shown only when record can be georeferenced.

Table 1
for details).

Table 2 .
Occurrence of A. reversura adults collected in several localities in Argentina.

Date of collection Male specimens of A. reversura Female specimens of A. reversura Collection techniches
Patitucci et al. | First record of Atherigona reversura in South America