Argentina Discovery

First record in Argentina of a plant-insect association, with interest in biological control

The species Chrysolina quadrigemina (Suffrian) (Coleoptera: Chrysomelidae) is recorded for the first time in Argentina, this being also the first record of this genus in the country. Its host plant, Hypericum perforatum L. (Clusiaceae) is native from Asia, Europe and Africa, and has behaved as a strong invader in several countries of the world where the implementation of a biological control program was necessary. The only country in South America that implemented such a control was Chile, in 1953. The arrival of C. quadrigemina to southern Argentina is probably due to natural dispersion from Chile. This record increases the number of Chrysomelidae species in the country.

Keywords: Coleoptera; Chrysomelidae; Chrysolina; Hypericum

INTRODUCTION

The St.-John‘s –wort, Hypericum perforatum L. (Clusiaceae), is a native of Asia, Europe and Africa (Julien & Griffiths 1998), widely naturalized elsewhere (Wiersema & León 1999). Holloway (1957) described it as an erect, freely branching perennial herb with a stem one to five feet high. Its flowers are yellow and occur in clusters; its light green leaves are numerous and paired along the stem. Its root crown has Comunicación breve many lateral runners which are capable of starting new plants; thus the spread of the plant is not entirely dependent on its seeds. These are produced in a pod which breaks into segments, releasing numerous small, cylindrical brown seeds which are spread by wind, water, man and animals (Holloway 1957). This plant has some positive values. It produces essential oils and lipids and Folk traditions assigned antiviral or antidepressive properties (Wiersema & León 1999).

However, it is considered a pest in most part of its exotic range. In the United States, St.- John‘s wort was first reported in 1793 near Lancaster. By 1940 the infestation of the weed had occupied 27 counties and 250.000 acres of range land. The economic damage that it produced was very important (Holloway 1957). As a weed, it competes with the cultivated forage. It is also an important poison for mammals and adversely affect cattle and sheep that graze on it (Holloway 1957). It also produces contamination of seeds as weed (Wiersema & León 1999).

Chrysolina hyperici (Foster) and Chrysolina quadrigemina (Suffrian) (Coleoptera: Chrysomelidae) are two biological control agents which were released in Australia (1930, 1980), Canada (1951), New Zealand (1943), Republic of South Africa (1960, 1973), and United States (1945) with the purpose to control Hypericum perforatum (Julien & Griffiths 1998). Liberation of the insects in these countries was done after exhaustive tests of host specifity; an established practice in biological control procedures (De Loach et al. 1989).

Hypericum perforatum L. has been recorded as a naturalized and widely distributed weed in Neuquén (area of Nahuel Huapi) and Chubut provinces, occasionally occurring in Buenos Aires and La Pampa provinces (Dimitri 1972; Cabrera 1965; Boelcke 1981; Zuluaga & Morrone 1999). Biological control of Hypericum has never been considered in Argentina (De Loach et al. 1989), but this weed has the potential to cause problems in the future, as happened in the United States (Boelcke 1981). In contrast, Chile has implemented a biological control program for this weed in 1953, in which both Chrysolina species were liberated and successfully established (Julien & Griffiths 1998). In 1952, 27300 adults of Chrysolina were imported from California and liberated in 1953. By 1959, 7000 ha were controlled (De Loach et al.1989).

The objective of this work is to describe the first record of Chrysolina quadrigemina (Suffrian) (Coleoptera: Chrysomelidae) in Argentina, and to discuss the relevance of this discovery under the context of biological control of the weed Hypericum perforatum L.

MATERIALS AND METHODS

During December 2004 and January 2005, the author was looking for chrysomelid fauna in different plants in Villa La Angostura, Península Quetrihue, Lago Correntoso, San Martín de los Andes (Neuquén Province) and San Carlos de Bariloche (Río Negro Province). Photos of the insects eating plants were taken and then, insect specimens were captured by hand on burgeons of living plants. One plant species was Hypericum perforatum. The presence of the beetles eating an exotic plant called the attention of the author. The chrysomelids taken from them were kept in the Entomology Division of the "Bernardino Rivadavia" Argentine National Museum, authors' collection Paola Turienzo, Buenos Aires, and Gary Piper, Washington, United States. The distinction from closely related Chrysolina species is difficult because of their similar size and color pattern (Piper 2004). For this reason, some specimens were sent to G. Piper, who identified them. The identification of the Hypericum species was done by O. R. Di Iorio, using Dimitri´s keys (1972).

In a second year of field work, during the months of December 2005 and January 2006, the author returned to the same places mentioned above and also visited a new locality, El Bolsón (Río Negro province) to search for this insect-plant association.

The methodology used was the same of the previous year. Only some specimens were taken from the plants and were kept in the Paola Turienzo´s collection, Buenos Aires, and Penner & Herrera´s collection (Essen, Germany). The total amount of specimens in each plant was counted.

RESULTS

From the two species liberated in Chile, Chrysolina hyperici (Foster) and Chrysolina quadrigemina (Suffrian) (Julien & Griffiths 1998), only the latter was found in Argentina. It was collected from Los Lagos Departament (Neuquén Province). Data of localities, date and number of specimens collected can be seen in Table 1. In Villa La Angostura, the plant was distributed in the town and around it, mainly in margin roads. D. Penner & L. Herrera (Essen, Germany) found them near Bariloche city, in the crossing of routes 237 and 231.

Insect distribution between plants was not uniform and few Hypericum plants were heavily infested; most of the individuals being free of beetles. For example, in Villa La Angostura town, during the summer of 2005-2006, only three groups of Hypericum attacked by Chrysolina were found. About 20 plants per group were observed to be infested by the beetles. The number of insects found ranged from one to six per plant.

Table 1. Localities, data and numbers of specimens of Chrysolina quadrigemina captured.
Tabla 1. Localidades, fechas y cantidad de especies capturadas de Chrysolina quadrigemina.

DISCUSSION

The insect genus has not been previously recorded for Argentina (Cabrera & Roig-Juñent 1998, 2004). Therefore, this constitutes a new record for the Chrysomelidae fauna of the country.

The presence of Chrysolina in southern Argentina is probably consequence of its natural dispersion from Chile, following patches of Hypericum throughout the years. The ability for dispersal of this species has been previously analysed by Holloway (1957), who described that it is capable of long, sustained flights.

It would be most interesting, in future studies about the plant and insect distribution, to conduct further research on the population dynamics of insects and their relations with biological control practices.

San Carlos de Bariloche is a city in the province of Río Negro, Argentina, situated on the foothills of the Andes, surrounded by lakes (Nahuel Huapi, Gutiérrez Lake, Moreno Lake and Mascardi Lake) and mountains (Tronador, Cerro Catedral, Cerro López). It is famous for skiing but also great for sight-seeing, water sports, trekking and climbing. Cerro Catedral is one of the most important ski centers in South America.

History

The name Bariloche comes from the Mapudungun word Vuriloche meaning "people from behind the mountain" (furi = behind, che = people). The Vuriloche pass was used by the Mapuches to cross the Andes and was kept secret from the European priests for a long time.

In 1672 the jesuits established in Chiloé Island founds a mission in the Nahuel Huapi Lake that last until 1717

Settlement

Settled primarily by Austrians and Germans about 1895, it was first named after pioneer Carlos Wiederhold was born in Germany but had migrated to San Carlos de Bariloche, who established a little shop called "La Alemana" near the present city center after crossing the Andes from Chile. Most of the commerce in Bariloche went by the seaport of Puerto Montt in Chile. In 1896 Perito Moreno wrote that it took three days to reach Puerto Montt from Bariloche while traveling to Viedma in the Atlantic coast took "one month or more". In letters addressed to him, he was erroneously addressed San Carlos instead of Don Carlos, which is why the city was called San Carlos de Bariloche.

In the 1930s the centre of the city was built to have the appearance of an alpine town with many buindings made of wood and stone. and a population of 93,600 (2001 census [INDEC], 1991: 77,600). In 1909 there were 1,250 inhabitants, telegraph, post office, and a road connecting the city with Neuquén. Commerce, however, continued to depend on Chile until the arrival of the railroad in 1934.

Between 1935 and 1940, the Directorate of National Parks carried over a number of urbanistic works, giving the city a characteristic beauty. Among them: the Civic Center (home of a Library, a Theatre, a Museum, the City Hall, the Post Office, the Police Station and the Customs), the Cathedral, Llao Llao Hotel, and others.

Second World War

Bariloche made headlines in the international press in 1995 when it became known that a former high ranking official of the SS 'Hauptsturmführer' Erich Priebke had been living there for years.^[1]

A typical log cabin in Bariloche.

Tourism

Tourism, both domestic and international, is the main economic activity of Bariloche, all year around. The main ski station is the one at Cerro Catedral. During the summer, beautiful beaches such as Playa Bonita and Villa Tacul welcome sun-bathers and some brave lake swimmers (the waters, from melting snow, are always very cold. Lake Nahuel Huapi averages 14 °C in the summertime). The fishing season is another great attraction. Bariloche is the biggest city of a huge Lakes District, and serves as a base for many excursions in the region. Trekking in the mountains, almost completely wild and uninhabited with the exception of a few high-mountain huts, is also a popular activity. The city is also famous for its chocolates.

It is also noteworthy that the city serves as the destination for Argentine secondary school students on their traditional senior year trips. The students are shepherded through week-long excursion packages including snowboarding, 4X4 excursions and passes to a series of night clubs. The students, who travel during their winter break in July, fill the town with mobs wearing identical, travel agency-issued cold-weather gear.

Science

Besides tourism and the many activities and services associated with it, Bariloche is home to first class scientific and technological activities. The Centro Atómico Bariloche [2] is a research center of the National Atomic Energy Commission, where basic and applied research in many areas of the physical sciences is carried out. One of its departments is the Instituto Balseiro [3], a higher education institution with a small and carefully selected number of students, that awards degrees in Physics, and in Nuclear and Mechanical Engineering, and Masters and Doctorate degrees in Physics and in Engineering. The city also hosts INVAP, a high technology company that designs and builds nuclear reactors and space satellites, among other projects. In addition, there are also several departments and laboratories of the Comahue University.

Climate and geography

Bariloche has an inland Temperate climate.

Transportation

The city is served by San Carlos de Bariloche International Airport (IATABRC/ICAO SAZS) equipped to receive any kind of aircraft. Several of the Argentina's most important airlines maintain regular flights to Bariloche, as well as some international lines from neighboring countries, especially during the ski season.

The city lies close to Chilean border and is connected to Chile by the Cardenal Antonio Samoré Pass crossing the Andes Mountains.