Siphoninus phillyreae (Haliday) is a polyphagous and widely distributed species that has shown a great capacity to invade new habitats. This species was first described as Aleyrodes phillyreae by Haliday in 1835, collected from Phillyrea latifolia L. (Oleaceae) in Dublin, Ireland, and later as Aleyrodes dubia by Heeger in 1859, from Fraxinus sp. (Oleaceae) in Laxenburg, Germany (CABI, 2024). The genus Siphoninus was described by Silvestri in 1915, who erected S. finitimus as the type species, which is currently considered a synonym of S. phillyreae (Mound & Halsey, 1978). In addition to A. dubia and S. finitimus, A. phillyreae, Aleurochiton dubius, Aleurodes phylliceae, Asterochiton phillyreae, S. dubiosa, S. granati, and Trialeurodes inaequalis are synonyms of S. phillyreae (Evans, 2008). The high number of synonyms of S. phillyreae can be attributed to the morphological variability of its pupal case (CABI, 2024).
Native to Europe, the Mediterranean, and North Africa (Nguyen & Hamon, 2020), S. phillyreae is found in numerous countries across Africa, Asia, Europe, North America, Oceania, and South America (CABI, 2024) (Fig. 1). In South America, it has been documented in Venezuela (Arnal et al., 1994), Chile (Munoz & Beéche, 1995), Argentina (Viscarret & Botto, 1997) and Peru (Valencia, 2011) (Fig. 2). As there is no reference to the presence of S. phillyreae in Brazil, this communication aims to record its occurrence in this country, based on collections from pomegranates Punica granatum L. (Lythraceae) in the state of São Paulo.
In Brazil, in January 2015, a consultation was held at the Agronomic Institute of Campinas (IAC) to identify an Aleyrodidae specimen infesting pomegranate leaves in a residence located in Campinas (São Paulo). In January 2021, a notable whitefly infestation occurred in Piracicaba (São Paulo) on a single pomegranate plant in another residence. Subsequently, also in Piracicaba, between January and April 2023, whitefly-infested pomegranate leaves were collected from nine plants: three in the Santa Rita neighbourhood (22°45'13.95"S; 47°35'9.61"W), four on the “Luiz de Queiroz” campus of ESALQ/USP (22°42'48.17"S; 47°37'35.15"W), one in a restaurant garden in the city center (22°44'3.90"S; 47°39'1.72"W), and one on the sidewalk of Carlos Botelho Avenue (22°42'49"S; 47°38'13"W). In Planaltina (Goiás) (15°26'50.7"S; 47°37'18.2"W), we found leaves of pomegranate infested with whitefly in December 2023; São João dos Patos (Maranhão) (6°30'19"S; 43°42'00"W) and Floriano (Piauí) (6°47'33"S; 42°59'26"W) in January 2024, and Janaúba (Minas Gerais) (15°49'54.09"S; 43°16'20.12"W) in February 2024. (Table 1) presents the average temperature and rainfall found on whitefly infestations along different locations in Brazil. All infestations were collected in locations with average temperature higher than 20 °C and average rainfall lower than 0.60 mm. In future work, more covariates and samples will be collected to aid whitefly infestation predictions in Brazil (Table 1).
Leaves from the collections at these locations were herborized, and subsequently, the pupal cases were mounted on microscopy slides following the protocols of Mound & Marullo (1996) and Hodges & Evans (2005). The genus Siphoninus is easily recognizable by its long siphon-like setae with expanded apices and operculum that only occupy the basal part of the vasiform orifice (Martin et al., 2000). Valencia (2011) provided morphological characters to distinguish S. phillyerae, found infesting ash (F. americana) and pomegranate (P. granatum) in Peru, from Siphoninus finitimus (Silvestri), a species synonymized with P. phillyreae by Mound & Halsey (1978), which he found on olives (O. europaea) in Peru and provided morphological characters to separate it from the former and removed it from synonymy. All specimens from these collections were compared with the characteristics given in Valencia (2011) for S. finitimus and S. phillyreae and were found to represent only S. phillyreae, representing the first record of its occurrence in Brazil (Fig. 2). Voucher specimens have been deposited as exsiccates of leaves and slides in the Museum of Entomology “Luiz de Queiroz” (MELQ) collection in Piracicaba (number ESALQENT001755-56) and the United States Natural History Museum (USNM), Smithsonian Institute, Aleyrodidae collection located in Beltsville, Maryland, USA (20705).
Infestation levels varied in the plants inspected in Piracicaba, depending on the observation time. Leaves with a high infestation of nymphs and adults (Fig. 3a-f) displayed wavy edges, and over time, the yellowing process initiated (Fig. 3g). Additionally, leaf fall from the branches of plants highly infested with S. phillyreae was observed. In other regions of Brazil where pomegranate leaves were collected only once (Goiás, Maranhão, Minas Gerais and Piauí).
In Piracicaba, 89 specimens of Encarsia Foerster (Hymenoptera: Aphelinidae) parasitoids were collected from nymphs of S. phillyreae. Morphological identification, performed using the keys of Polaszek et al. (1992, 2004), confirmed all specimens as Encarsia brasiliensis (Hempel) (formerly Encarsia hispida De Santis) (Fig. 4). Molecular characterization of these parasitoids and their hosts was conducted. Genomic DNA extraction from the specimens we identified as E. brasiliensis and S. phillyreae followed the non-destructive extraction method adapted for microhymenopteran extraction (Wengrat et al., 2021).
Two fragments of the mitochondrial gene (mtDNA) cytochrome c oxidase subunit I (COI) and the D2 expansion region of the 28S rDNA gene (28S-D2) were sequenced for the parasitoids and a COI fragment was sequenced for the whitefly. COI was amplified using the primers LCO 1490/HCO 2198 (Folmer et al., 1994) for parasitoids and whiteflies; also, for parasitoids, was amplified with primers C1-J-2183/TL2-N-3014 (Simon et al., 1994), as well as the 28S-D2 region with primers D2F/D2R (Campbell et al., 1993). PCR conditions for amplification of the COI and 28S-D2 fragments were as described in Gariepy et al. (2014), with modifications to the annealing temperatures: 50 ºC for the LCO-HCO, 51 ºC for 2183-3014, and 55 ºC for D2F and D2R. Amplicons were visualized under ultraviolet light after 1.5% agarose gel electrophoresis stained with SYBR Safe. PCR products were purified and sequenced by the Sanger method at the Agricultural Biotechnology Laboratory (CEBTEC).
Sequences were deposited at GenBank under the accession numbers OR807273-OR807275 (LCO/HCO), OR807264-OR807268 (2183/3014), and OR807261-OR807263 (28S) for E. brasiliensis and PP153921-PP153925 (LCO/HCO) for S. phillyreae.
After the DNA extraction, parasitoid specimens preserved in ethanol 75% were mounted on slides following the methodology of Huber (2015). Voucher specimens were deposited at the “Oscar Monte” Entomophagous Insect Collection (IB-CBE) at the Instituto Biológico, Campinas, Brazil, under the unique identifiers IB-CBE 001871 to IB-CBE 001875.
This represents the second record of E. brasiliensis as a parasitoid for S. phillyreae, since Valencia (2011) also reported it from Peru, as E. hispida. Encarsia hispida was synonymized with E. brasiliensis by Polaszek et al. (2004). This is an example with strong reasons for a reversal of precedence, as discussed by Polaszek et al. (2004); however, their publication was the last official act on the taxonomy of the species. Encarsia brasiliensis has already been reported in the Brazilian states of São Paulo (Hempel, 1904; Polaszek et al., 2004), Minas Gerais (Polaszek et al., 2004; Torres et al., 2014), Bahia (Lourenção et al., 2007), Distrito Federal (Oliveira et al., 2003), Paraíba (Oliveira et al., 2019), and Maranhão (Dias-Pini et al., 2020) parasitizing Bemisia tabaci (Gennadius), Trialeurodes variabilis (Quaintance), and Aleurodicus cocois (Curtis); therefore, it likely has a wide distribution in the country.
In Brazil, the pomegranate tree is often grown as an ornamental plant in gardens due to the beauty of its leaves, flowers, fruits, and medicinal properties (Bonome & Tomazi, 2022).
Considering the potential spread of S. phillyreae in pomegranate cultivation areas and other crops attacked by this whitefly, evaluating the efficiency of Aleyrodidae parasitoids in Brazil is essential for its control. Most known species have been reported to parasitize B. tabaci (Oliveira et al., 2003; Lourenção et al., 2014; Torres et al., 2014; Oliveira et al., 2019). Notably, E. inaron, responsible for the reduction of S. phillyreae populations in the USA, is present in São Paulo, Minas Gerais, and the Federal District (Oliveira et al., 2003; Lourenção et al., 2014; Torres et al., 2014). Thus, in addition to the presence of E. inaron in Brazil, which is a proven efficient biological control agent of S.phillyreae, there is evidence of natural parasitism by E. brasiliensis, as observed in this study. The combined presence of E.inaron and E. brasiliensis could contribute to the sustainable control of this whitefly pest.