Increased frequencies of Zaprionus indianus Gupta, 1970 (Diptera, Drosophilidae) in Uruguay.

Transcription

1 Goñi, B., M.. Martinez*, G. Techera, and P. Fresia Increased frequencies of Zaprionus indianus Gupta, 1970 (Diptera, Drosophilidae) in Uruguay. Dros. Inf. Serv. 85: Increased frequencies of Zaprionus indianus Gupta, 1970 (Diptera, Drosophilidae) in Uruguay. Goñi, B., M.. Martinez*, G. Techera, and P. Fresia. Sección Genética volutiva and *Sección ntomología, Facultad de Ciencias, Instituto de Biología, Universidad de la República, Igua 4225, Montevideo 11400, Uruguay. -mail: The opportunity to monitor the colonization of an organism is a rare privilege of a biologist. Zaprionus indianus is a drosophilid originally from the Afrotropical region and has recently been introduced in the American continent (reviewed by Vilela et al., 2001). Since its first record in Brazil (Santa Isabel, State of São Paulo) on March 1999 (Vilela, 1999), Z. indianus has rapidly become widespread to southern latitudes. It was recorded with relative frequencies as high as 45% in Southern Brazil (De Toni et al., 2001; Castro and Valente, 2001) and was detected for the first time in some localities of Uruguay on April and May 2000 (Goñi et al., 2001). Having the privilege to study the current colonization of Z. indianus in Uruguay, we present one year collection data of drosophilids from several localities of Uruguay and analyze some native as well as exotic fruits as the potential breeding and feeding sites of this species. Table 1 shows the localities, the main biogeographical data and environmental features, dates and resources used in each locality. The localities surveyed are arranged into two groups: (A) those sampled in the period April 1999 to May 2001 (see Goñi et al., 2001), and (B) those newly sampled. Data from the first group of localities (Faculty of Agronomy, Santa Lucia and the Rocha s wetland), enable us to compare previous data of the breeding and feeding site preferences of Z. indianus over time (Goñi et al., 2001). The second group allows us to investigate the course of invasion of Z. indianus in other natural areas (like the Farrapos wetland) and urban or suburban areas (Rivera city, Castillo city, Solis beach resort). Since Z. indianus was reported for the first time as a pest of commercial figs (Ficus carica) in the Valinhos area (State of São Paulo) (Vilela et al., 1999, 2001), Uruguayan localities under intensive fruit farming management (Mi Granja, Los Chimangos, and SOFOVAL) were sampled. Adult flies were caught on rotting fruits and/or banana baits to obtain data on adult feeding sites (Table 1). When available, fruits of both exotic and native plants were collected to obtain data on larval breeding sites (Table 1). We followed the procedure described in Goñi et al. (1998), but avoided the use of anesthetic substance (triethylamine) during fly collection at the Rocha localities. A total of 13,602 flies were collected during the period December 2001-May They belonged to species members of the genus Drosophila (Goñi et al., unpublished data) and to the species Zaprionus indianus. Table 2 indicates the number and the relative frequency of Z. indianus in relation to a given sample and the substrate used as feeding and/or breeding site. In general, data from the localities of group (A) (Table 2, Faculty of Agronomy, Santa Lucia and Rocha) show that: (i) Z. indianus was able to colonize new breeding sites, and (ii) showed a substantial increment in its relative frequency in relation to data from the period (Goñi et al., 2001). In the locality of Faculty of Agronomy, Z. indianus emerged from fruits of the three native palms surveyed, Butia capitata, Butia yatay and Syagrus romanzoffiana. Z. indianus quadruplicated its frequency of preference in the breeding sites of Butia yatay from 0.35% (May, 2000) to 1.49% Table 1. Localities, main biogeographical features, date of collection and resources used at each locality.

2 Localities and main biogeographical features 1 Date 2 (month, year) Resources used as bre Origin of (B) and/or feeding (F) substrate A. Sampled ( ) 1 Faculty of Agronomy, Montevideo City (34 53 S; W). Surrounded by a belt of intensive farming. Urban. March, 2002 Butia capitata (B, F) Syagrus romanzoffiana (B) April, 2002 (a) Gingko biloba (F) April, 2002 (b) Butia yatai (B, F) Butia capitata (F) Gingko biloba (F) Psidium littorale (F) Santa Lucía city. Adami ranch, Km 2.500, Route 81, Canelones (34 27 S; W). Vineyard. February, 2002 Malus sylvestris (B) The Atlantic wetlands (37º 87 S; 59º 82 W), the Don Bosco's camp, Laguna egra, Rocha. Locality I. Low hill, natural gallery forest. Ficus luschnatiana (F*) Myrcine laetevirens (F*) Schinus longifolium (F*) Locality II. Floody area. Area of livestock breeding. atural. Schinus longifolius (F, F*) Butia capital (F, F*) Locality III. Coastal belt of Laguna egra. atural. Cereus spp. 3 (F*) Opuntia spp. 3 (F*) Locality IV. Low hill. Area of livestock breeding. atural. Cereus spp. 3 (F*) Opuntia spp. 3 (F*) B. Others Mi Granja ranch, Km , Route 1, Arazatí, San José (34 25 S; W). Intensive fruit farming. December, Prunus armeniaca (F, F*) Los Chimangos ranch, Km 6.000, Route 49, Las Brujas, Canelones (34 34 S; W). Intensive fruit farming. December, 2001 Ficus carica (F) Prunus persica (F, F*) SOFOVAL Rural Soc., Km , Route 1. Colonia Valdense, Colonia (34 20 S; W). Intensive fruit farming. February, 2002 Ficus carica (B) Rivera city, Rivera (30 54 S; W). Urban. March, 2002 ugenia uruguayensis (B) Solís beach resort, Route Interbalnearia, Km 83, Maldonado (34 47 S; W). Rio de la Plata coast. Suburban. Butia capitata (B, F) Castillos city, Rocha (34 12 S; W). Urban. May 2002

3 Farrapos wetlands, Rio egro (32 40 S; W). Locality I. Puerto Viejo camp, Uruguay river. atural. Locality II. San Javier city. Uruguay river. Urban. April, 2002, Mayo, 2002 Locality III. Stream Isletas. atural Locality IV. Stream Farrapos. atural. Locality V. Stream Román Chico. atural. 1 For further details see Goñi et al 1998, Collected on April 8th (a) and 21st (b). 3 F*= Adult flies collected on banana-baited trap over the resource(s) indicated. 4 Adult flies collected on fruits of both resources simultaneously, as indicated. =native, =exotic. 1 Corrigendum in Goñi et al 2001: Myrcine laetevirens (here) is synonymous of Rapaena laetevirens, Butia yayai should read Butia yatay, and Psidium guayaba (in Santa Lucía locality) should read Feijoa sellowiana. Table 2. Percentage of Zaprionus indianus in the total sample along with the resources used as feeding and/or breeding sites in each locality. o. Z. Indianus/ Localities of Uruguay 1 Dates 1 Resources used as feeding (F) and/or 1 breeding (B) sites total sample % A.- Sampled ( ) 1 Faculty of Agronomy March, 2002 Butia capitata (B) Butia capitata (F) Syagrus romanzoffiana (B) 27/1204 2/22 4/31 1/292 1/ April, 2002 (a) Gingko biloba (F) 3/ April, 2002 (b) Butia yatay (B) Butia yatay ( F) 3/202 1/ Butia capitata (F) Gingko biloba (F) Psidium littorale (F) 71/819 16/79 122/ / Santa Lucia February, 2002 Malus sylvestris s(b) 2/ Rocha s wetland. Locality I Ficus luschnatiana 3, Myrcine laetevirens 3 & Schinus longifolius 3 (F*) 4/ Idem. Locality II Schinus longifolius, Butia capitata (F, F*) 5/369 56/ Idem. Locality III May 2002 Cereus spp., Opuntia spp. (F*) 65/ Idem, locality IV Cereus spp., Opuntia spp. (F*) 69/ B. Others

4 Mi Granja ranch. San José December, 2001 Prunus armeniaca (F, F*) 0/428 0 Los Chimangos ranch, Canelones December, 2001 Ficus carica (F) Prunus persica (F, F*) 0/171 0/ SOFOVAL, Colonia February, 2002 Ficus carica (B) 92/ Rivera city, Rivera March, 2002 ugenia uruguayensis (B) 31/ Solis resort, Maldonado Butia capitata (F) Butia capitata (B) 6/311 23/ Castillos city, Rocha 24/ Farrapos wetlands. Locality I 0/167 0 Idem, locality II April, /67 17/ Idem, locality III 3/ Idem, locality IV 2/ Idem, locality V 15/ As I in Table 1 (), while it showed even higher frequencies in the palms Butia capitata (2.24%). When native and exotic resources sampled at this locality were used as feeding sites, the frequencies of Z. indianus in the sample run from 3.26% to 20.05%. In the Santa Lucía locality, Z. indianus was found to breed in the commercial apple, Malus sylvestris, an exotic resource, but not in others (Feijoa sellowiana, Ficus carica, Prunus cerassifera and Vitis vinifera, sampled in February 2002, data not shown). Data on the Atlantic wetlands (Rocha) is quite interesting. This area is quite rich in native resources with woody communities of rythrina crista-galli ( ceibo ), Phytolacca dioica ( ombú ), and Cephalanthus glabratus ( sarandí colorado ) trees. The locality I at the Don Bosco camp is a low hill of gallery forest with native trees, shrubs, cacti, vines and epiphytics. Among the trees, we find Myrcine laetevirens ( canelón ), Schinus longifolium ( molle ), Ficus luschnatiana ( higuerón ), Citharexylum montevidense ( tarumán ), Lithraea brasiliensis ( aruera ), Scutia buxifolia ( coronilla ), Celtis tala ( tala ), Blepharocalyx salicifolius ( arrayán ) and Allophyllus edulis ( chal chal ), the shrubs Colletia paradoxa ( espina de la cruz ) and Daphnopsis racemosa ( envira ), the cacti Cereus spp. and Opuntia spp, and also the native palms, Butia capitata ( palma butiá ) and Syagrus romanzoffiana ( palma pindó ). Samples from banana-baited traps at this locality (which corresponds to locality II in Goñi et al. (2001) showed the lowest frequency (0.49%) of all samples collected in the Don Bosco camp. Fly samples from localities (II, III and IV), found at areas perturbed by livestock breeding, showed increased frequencies of Z. indianus, from 1.35% to 7.21% (Table 2). All these localities are quite close to each other, in a radius of less than 3 km. We should note that Z. indianus was previously recorded at a low frequency (0.10%) at the coastal belt of -Laguna egra lake (locality III here) on May 2000 but rose, rising to 7.21% two years later (Table 2). These data indicate that Z. indianus was able to colonize both urban and natural areas, being less frequent at localities where the natural environment is well preserved. Another natural area sampled was the Farrapos wetland. The Farrapos wetland corresponds to a lacustral system of about 6300 hectare, extending along the Uruguay river, and forming a rich ecosystem

5 characterized by stable or almost stable floody areas. It is greatly influenced by (i) the Farrapos own basin drainage, (ii) the Uruguay river annual flow variation, and (iii) the Rio de la Plata southeastern eolic tides known as the sudestadas (Achkar et al., in press). A particularly rich ecosystem of diverse species of plants and animals is associated with extended wetland. Woody communities of rythrina crista-galli ( ceibo ) and Cephalanthus glabratus ( sarandí colorado ) trees are the common components of the landscape in the localities surveyed. This area has an annual mean precipitation (averaged ) of mm and an annual mean temperature (averaged ) of 17.9 C. The sampled localities at Farrapos wetland are within a radius (north to south) of about 6 km. Data in Table 2 indicate that Z. indianus was frequently collected over banana-baited traps in most of the localities surveyed. There are no previous reports of drosophilids from this natural area. As shown in the other sampled localities of group (B) (Table 2), Z. indianus emerged from native fruits Butia capitata, and ugenia uruguayensis ( guayabo blanco ), a widespread Myrtaceae at northern regions of Uruguay, and from figs, Ficus carica, collected at the fruit farm SOFOVAL. However, in a few localities Z. indianus was not collected from fruits of exotic orchard plant species, Prunus armeniaca, Prunus persica, included figs, Ficus carica. As a generalist species (Chassagnard and Kraaijeveld, 1991) Z. indianus has been able to colonize new geographic regions, reinforcing its status as a semicosmopolitan species in the tropical and also the subtropical eotropical region. In its route to southern latitudes, Z. indianus was able to colonize Uruguayan territory, at temperate regions, exploiting both native neotropical fruits, as well as exotic fruits for adult feeding and larvae breeding. The overall frequency of Z. indianus in Uruguay has increased dramatically in the last couple of years; however, it is less frequent or even absent in highly disturbed environmental areas, like those of intensive fruit farming where insect pheromone treatment and chemicals are routinely used, and in areas where the natural environment is most preserved, like the gallery forest locality at the Don Bosco camp inserted in a natural area of the Atlantic wetlands. It is expected that drosophilid communities at this wild area may be well adapted to the array of different resources available and to the different successional stages of a particular native resource. More information on the natural breeding and feeding sites of eotropical drosophilids is needed for a better understanding of Z. indianus in our region. Furthermore, as noted by Brncic (1983), the determination of the natural living sites of drosophilids requires the consideration of many other factors besides nutrition. Among other things, it requires a knowledge of abundance and periodicity of substrates utilized, of the faunistic associations existing in the region inhabited by the flies, and of climatic and geographic factors. Finally, to understand the environmental conditions influencing live organisms in this geographic region we include here some pertinent climatic data that deserve to be considered. Uruguay is the only South American country entirely found in the temperate region. The lack of important orographic systems do not contribute to large variations in temperature, precipitation and other parameters. The annual mean temperature for the country is around 17ºC. The Atlantic semipermanent anticyclon influences the development of the weather in Uruguay, the horizontal circulation that it originates determines a predominantly northeastern to eastern direction of the wind and brings air masses of tropical origin ( However, two aspects of climate should be considered for Uruguay (agy et al., 2002): i) there is a high difference in the annual mean precipitation between the southernmost (Prado-Montevideo city, about 1200 mm) and northernmost (Bella Union city, about 1500 mm) meteorological stations. (ote that these stations are about 600 km apart from each other); ii) Precipitation has increased extraordinarily in the last century, i.e., at Prado station it went from less than 1000 mm to more than 1200 mm. A similar trend was observed at Bella Union station, from 1250 mm to 1500 mm. The most astonishing fact is that this trend has been most

6 striking in the last decade. Likewise, air temperature has increased about 0.8ºC since 1883 (Prado station), from an annual mean temperature of 16ºC to 16.8ºC. Similarly, the temperature increase has been most striking in the last two decades. These climatic trends suggest that Uruguay is at a crossroad between the subtropical and temperate biogeographic regions, with signals of becoming a subtropical region. Organismal bio-indicators of drastic environmental changes like drosophilids offer a useful tool to detect such changes; however, to use them in environmental projects in our region, knowledge of the faunal composition and population structure of this group of insects is much needed. Acknowledgments: This work was done with serious financial limitations, but with the kind support of many persons. We thank specially C.R. Vilela (Dep. Biología, Universidade de São Paulo) for encouraging us during the course of this study. We sincerely thank: Ing Agr. L. Delfino (Jardín Botánico, Montevideo); Lic G. Fernández, MSc. A. Domínguez and Lic. V. Fernández (Geografía, Facultad de Ciencias); Dr. G. agy (Facultad de Ciencias, Proyecto AIACC LA32); Lic. M. Calviño and Bach M.J. Ferreiro and Mr. C. Olivera Tito (Facultad de Ciencias); Ing. Agr. J. Alvear ( Mi Granja ), Ing. Agr. C. M. Ramirez (SOFOVAL), Ing. Agr S. Toriño ( Los Chimangos ) and Mr. F. Ramos (Don Bosco camp). We also thank Prof.. Scvortzoff (PDCIBA, Universidad de la República), for the critical reading. This study was partly supported by CSIC to BG. References: Achkar M., V. Canton, R. Cayssials, A. Domínguez, G. Fernández, F. Pesce, and B. Sosa, LORLA, Université de Toulouse-Le Mirail. France. IPALT. In press; Brncic, D., 1983, In: The Genetics and Biology of Drosophila (Ashburner, M., H.L. Carson, and J.. Thompson, jr., eds.), vol 3d, pp , Academic Press, Y; Castro, F., and V.L.S. Valente 2001, Dros. Inf. Serv. 84: 15-17; Chassagnard, M.Th., and A.R. Kraaijeveld 1991, Ann. Soc. ntomol. Fr. (.S.) 27(4): ; De Toni, D., P.R.P. Hofmann, and V.L.S. Valente 2001, Biotemas 14(1): 71-85; Goñi, B., P. Fresia, M. Calviño, M.J. Ferreiro, V.L.S. Valente, and L. Basso da Silva 2001, Dros. Inf. Serv. 84: 61-65; Goñi, B., M.. Martinez, V.L.S. Valente, and C.R. Vilela 1998, Revta. bras. nt. 42: ; agy, G., M. Bidegain, M. Caffera, C. Lopez, A. Ponce, and G. Sención 2002, in Perfil ambiental del Uruguay, 2002 (Dominguez, A., and R.G. Prieto, eds.), pp , ordan-comunidad, Montevideo; Vilela, C.R., 1999, Dros. Inf. Serv. 82: 37-39; Vilela, C.R.,.P. Teixeira, and C.P. Stein 2001, in: Histórico e impacto das pragas introduzidas no Brasil (Vilela,.F., R.A. Zucci, and F. Canton, eds.), Chapter 7, pp , Holos, São Paulo, Brazil.