We report Neosilba pradoi and Dasiops frieseni (Diptera: Lonchaeidae) for the first time in Uruguay, which is the most southern distribution yet found for these species. Moreover, new host associations are recorded: D. frieseni in Citrus sinensis cv. Valencia and an undetermined lonchaeid in Acanthosyris spinescens.
The members of the family Lonchaeidae (lance flies) are glossy black color with a blue or green metallic shine, or a mixture of both blue and green. The larvae usually are saprophagus or frugivorous (Bentancourt et al. 2009). This family is very well represented in South America, although knowledge of the frugivorous Lonchaeidae is just being developed; presently, little or nothing is known about the identity and biology of the many South American species (Korytkoioski & Ojeda 1971; Norrbom & McAlpine 1997; Strikis et al. 2011; Gisloti et al. 2017).
The family Lonchaeidae possibly has received little attention because several species are opportunists associated with fruit fly (Diptera: Tephritidae) infestations (McAlpine & Steyskal 1982), rather than being primary pests. However, Araujo & Zucchi (2002), Aguiar-Menezes et al. (2004), Strikis & Lerena (2009), and Nicácio & Uchôa (2011) found that some species were primary invaders, and not dependent on previous oviposition by tephritids.
In Uruguay, there have been few reports of Lonchaeidae associated with fruit. Dasiops uruguayensis, described by Enderlein in 1936 (Korytkoioski & Ojeda 1971), and Lonchaea chalybea Wiedemann are the only records for this country (Ruffinelli & Carbonell 1954).
Between Nov 2013 and May 2014, mature fruits were collected from potential hosts of Diptera in Salto (31.3865°S, 57.7176°W) and Canelones (34.6207°S, 56.3612°W), Uruguay. Fruits (from plants or recently fallen) were collected from 18 plant species (Table 1). The samples were counted, weighed, and stored individually in screen-covered plastic pots containing sterile sand, and kept at 25 °C. The emerged adults were preserved in 70% ethanol for identification.
Species of plants sampled, fruit weight, number of fruits sampled, number of adult Lonchaeidae emerged, average number of adults per kg, and percentage of fruit infested.
Numbers of adults of Neosilba pradoi and Dasiops frieseni by host, average number of adults per kg, and percent of fruit infested.
A total of 47 specimens of Lonchaeidae were obtained from 6 plant species. Forty specimens were identified as Neosilba pradoi Strikis & Lerena 2009 (Lonchaeinae) and Dasiops frieseni Norrbom & McAlpine, 1997 (Dasiopinae). The rest were identified only to family level. These two species are recorded for first time in Uruguay (Table 2). A total of 5 males and 9 females of N. pradoi emerged from fruits collected from plants, and 14 males and 12 females of D. frieseni from fruits collected from both the plants and on the soil beneath the trees. In most fruits (85% of those infested) a single species emerged, but in one fruit of Psidium cattleianum Sabine (Myrtaceae) and one of Citrus sinensis (L.) (Rutaceae), adults of Anastrepha fraterculus (Wiedemann) and Ceratitis capitata (Wiedemann) (both Diptera: Tephritidae) emerged along with the lonchaeids, respectively. As noted previously, some species of Lonchaeidae should be considered to be of economic importance and regarded as primary invaders. Though sometimes associated with tephritid infestation, lonchaeids seem to be independently capable of attacking fruit (Uchôa 2012).
In Brazil, N. pradoi has been reported to occur in Passiflora caerulea L. (Passifloraceae), though Marsaro et al. (2012) found lower levels of infestation as compared to us (28.4 larvae per kg of fruit infested by N. pradoi or Lonchaea sp.). Moreover, Eugenia uniflora (L.) (Myrtaceae) and Citrus sinensis were described as hosts by Garcia & Norrbom (2011). They found infestation levels (2.7 adults per kg and 4.0 adults per kg, respectively) similar to what we observed, but this is the first time that N. pradoi has been found in the orange cv. Valencia. Aguiar-Menezes et al. (2004) found that D. frieseni had the highest infestation index (considering lonchaeids and tephritids) infesting Passifloraceae spp. in southeastern Brazil.
This study is the first report of these species for Uruguay and it is the most southern detection of them, and thus can aid in the determination of the species' distribution and ecology. In addition, this is the first record of Acanthosyris spinescens Griseb. (Santalaceae) as host for a lonchaeid. More extensive and intensive surveys of lonchaeid hosts should be conducted in Uruguay to improve our knowledge of the diversity and ecology of these important dipteran species, which could have important effects on fruit production.
We thank Dr. Pedro Strikis (University of São Paulo, Brazil) for identifying the insects, Wuilliam Techeira (MGAP Salto), Emily Silva Araujo (Federal University of Pelotas) and Facultad de Agronomía (Salto) for helping during fruit collection. We also thank Capes-UdelaR and Agencia Nacional de Investigación e Innovación for financial support.