Biologia de Microctonus sp. (Hymenoptera: Braconidae), parasitóide de Cyrtomon luridus BOH. (Coleoptera: Curculionidae)

Cyrtomon luridus (Boh.), a native insect of wild Solanaceae, has adapted to the medicinal plant Duboisia sp., introduced from Australia, causing damages up to 100% mortality. Microctonus sp. is the most important natural enemy of C. luridus and its potential for biological control was investigated in this work. This study was carried out in Arapongas, Paraná State, Brazil, from 1994 to 1996. Parasitism of C. luridus by Microctonus sp. was highest from February through June (maximum of 54% in May 1996), when the C. luridus adult population was decreasing. The female sex ratio of Microctonus sp. under natural conditions was 0.57 to 0.69, which was close to 1 male : 2 female. Production of males occurs parthenogetically (arrhenotoky). In the laboratory, parasitism reached 40% when two adult C. luridus were exposed per parasitoid. The number of Microctonus sp. adults that emerged per parasitized beetle ranged from 4.7 to 14.2. Larval-pupal viability was 31.7 to 64.8% and the female sex ratio ranged from 0.0 to 0.37, with prevalence of males. The egg-pupal period was 12.7 days and the pupal-adult period was 10.7 days, resulting in a mean life cycle (egg-adult) of 22.4 days for this parasitoid (25ºC, 70% R.H.). This is the first report of a new species of Microctonus sp. in C. luridus.Cyrtomon luridus (Boh.) é um inseto nativo de solanáceas silvestres e se adaptou à planta medicinal Duboisia sp., introduzida da Austrália, causando danos de até 100% de mortalidade. Microctonus sp. é o mais importante inimigo natural de C. luridus e seu potencial para o controle biológico foi investigado neste trabalho. Os experimentos foram conduzidos em Arapongas, Estado do Paraná, de 1994 a 1996. O parasitismo de C. luridus, por Microctonus sp. foi maior nos meses de fevereiro a junho (máximo de 54% em maio/96), coincidindo com a diminuição da população de adultos de C. luridus. A razão sexual de fêmeas de Microctonus sp., em condições naturais, foi de 0,57 a 0,69; sem cópula há produção de machos (partenogênese arrenótoca). Em laboratório, o parasitismo chegou a 40%, quando se ofereciam 2 adultos de C. luridus para 1 parasitóide. O número de adultos de Microctonus sp. por besouro parasitado variou de 4,7 a 14,2; a viabilidade larval-pupal de 31,7 a 64,8% e a razão sexual de 0 a 0,37, com predominância de machos. O período ovo-adulto foi em média, de 22,4 dias, sendo 12,7 dias para o período ovo-pupa e 10,7 dias para o período pupa-adulto (a 25º C; 70% de U.R). Estes foram os primeiros resultados da biologia desta nova espécie de Microctonus, parasitóide com potencial a ser avaliado para o controle biológico de C. luridus

Population dynamics of Cyrtomon luridus Boheman (Coloptera: Curculionidae) on Duboisia sp. (Solanaceae) in Brazil

Cyrtomon luridus (Boheman) has adapted to the medicinal plant Duboisia sp., introduced from Australia. Its larvae feed on roots, causing up to 100% mortality damages. The population dynamics and biological cycle were studied to determine future control methods in Duboisia sp., in Arapongas, Paraná State, Brazil, from 1993 to 1996. C. luridus presented annual life cycle in Duboisia sp. under natural conditions. The larval development period was 120 to 150 days, from January to May, reaching an average size of 19.0 ± 2.0 mm in soil depth ranging on 24.9 ± 8.6 cm to 45.0 ± 10.0 cm. The beginning of the pupal phase happened in April. The larval-adult viability ranged on 7.5% to 19.6%. The typical symptoms of attack appeared in an infestation level of 60 larvae per plant. The first adults came out in July, six months after larvae hatching. However, adults came out from soil only in September, at the beginning of the rainy season, reaching the peak of emergency in October, outspreading until January. In laboratory (25ºC, 70% R.H.), females longevity averaged 113.7 ± 15.2 days. In this period, laying capacity was 42.7 ± 7.9 egg masses, with 9.4 ± 0.61 eggs each, totaling 402 ± 72.9 eggs per female. Adults C. luridus were found parasitized by Microctonus sp. (Loan) (Hymenoptera: Braconidae). Solanaceae species Solanum mauritianum Scopoli and Cestrum intermedium Sendt. were identified as host plants of C. luridus.Cyrtomon luridus (Boheman) adaptou-se à planta medicinal Duboisia sp., introduzida da Austrália, na qual causa danos de até 100%. A dinâmica populacional e o ciclo biológico foram estudados de 1993 a 1996, em Arapongas, PR, Brasil, com o objetivo de determinar futuros métodos de controle em Duboisia sp.. C. luridus apresentou ciclo anual em Duboisia sp. em condições naturais. O período de desenvolvimento larval ocorreu em 120 a 150 dias, de janeiro a maio, atingindo o tamanho médio de 19.0 ± 2.0 mm a uma profundidade média no solo de 24.9 ± 8.6 cm a 45.0 ± 10.0 cm. Em abril, foi observado o início da fase pupal. A viabilidade do período larval-adulto variou de 7.5% a 19.6%. Os sintomas típicos de ataque apareceram com o nível de infestação de 60 larvas por planta. Os primeiros adultos surgiram em julho, seis meses após a eclosão das larvas. Entretanto, o início da emergência de adultos do solo foi em setembro, no início da estação chuvosa, atingindo o pico de emergência em outubro, estendendo-se até janeiro. Em laboratório (25ºC, 70% UR), a longevidade média das fêmeas foi de 113.7 ± 15.2 dias. Neste período, cada fêmea colocou 42.7 ± 7.9 massas de ovos com 9.4 ± 0.61 ovos cada, totalizando uma média de 402 ± 72.9 ovos por fêmea. Adultos de C. luridus foram encontrados parasitados por Microctonus sp. (Loan) (Hymenoptera: Braconidae). As espécies de Solanaceae Solanum mauritianum Scopoli e Cestrum intermedium Sendt. foram encontradas como plantas hospedeiras de C. luridus

Population dynamics of Cyrtomon luridus Boheman (Coloptera: Curculionidae) on Duboisia sp. (Solanaceae) in Brazil

Cyrtomon luridus (Boheman) has adapted to the medicinal plant Duboisia sp., introduced from Australia. Its larvae feed on roots, causing up to 100% mortality damages. The population dynamics and biological cycle were studied to determine future control methods in Duboisia sp., in Arapongas, Paraná State, Brazil, from 1993 to 1996. C. luridus presented annual life cycle in Duboisia sp. under natural conditions. The larval development period was 120 to 150 days, from January to May, reaching an average size of 19.0 ± 2.0 mm in soil depth ranging on 24.9 ± 8.6 cm to 45.0 ± 10.0 cm. The beginning of the pupal phase happened in April. The larval-adult viability ranged on 7.5% to 19.6%. The typical symptoms of attack appeared in an infestation level of 60 larvae per plant. The first adults came out in July, six months after larvae hatching. However, adults came out from soil only in September, at the beginning of the rainy season, reaching the peak of emergency in October, outspreading until January. In laboratory (25ºC, 70% R.H.), females longevity averaged 113.7 ± 15.2 days. In this period, laying capacity was 42.7 ± 7.9 egg masses, with 9.4 ± 0.61 eggs each, totaling 402 ± 72.9 eggs per female. Adults C. luridus were found parasitized by Microctonus sp. (Loan) (Hymenoptera: Braconidae). Solanaceae species Solanum mauritianum Scopoli and Cestrum intermedium Sendt. were identified as host plants of C. luridus