Biological Activity of Bacillus thuringiensis (Bacillales: Bacillaceae) in Anastrepha fraterculus (Diptera: Tephritidae).

Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) is considered to be one of the major pest insects in fruit orchards worldwide. Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) strains are widely used as biological control agents and show high biological activity against different insect species. The objective of this study was to evaluate the biological activity of different strains of B. thuringiensis against A. fraterculus larvae and adults. Bioassays were performed using suspensions of bacterial spores/crystals of B. thuringiensis var. israelensis (Bti), kurstaki (Btk), and oswaldocruzi (Bto) strains at three concentrations [2 × 107, 2 × 108, and 2 × 109 colony-forming units per ml (CFU ml-1)]. At a concentration of 2 × 109 CFU ml-1, a significant larval effect (mortality 60%) was observed when compared with the control treatment. Larvae that ingested spore/crystal suspensions of Bti, Btk, or Bto bacterial strains exhibited significant larval and pupal deformations, leading to a significant decrease (~50%) in the completion of the insects' biological cycle (egg to adult). The B. thuringiensis strains (Bti, Btk, or Bto) at a concentration of 2 × 109 CFU ml-1 in combination with one food attractant (BioAnastrepha 3% or CeraTrap 1.5%) in formulations of toxic baits provided high mortality (mortality > 85%) of A. fraterculus adults 7 d after treatment. However, the Btk strain in combination with CeraTrap 1.5% caused mortality of 40%. On the basis of these results, the native bacterial strains Bti, Btk, and Bto were considered to be promising candidates as biological control agents against A. fraterculus.

Moscas frugívoras e seus parasitoides nos municípios de Pelotas e Capão do Leão, Rio Grande do Sul, Brasil / Frugivorous flies and their parasitoids in the cities of Pelotas and Capão do Leão, Rio Grande do Sul, Brazil

As moscas frugívoras (Tephritoidea) são as principais pragas da fruticultura de clima temperado no Brasil. O objetivo do presente trabalho foi avaliar a infestação desses dípteros e a ocorrência de seus parasitoides em frutíferas nos municípios de Pelotas e Capão do Leão, localizados na região Sul, nas safras agrícolas de 2007/08 e 2008/09. Foram coletados frutos de araçazeiro-amarelo e vermelho (Psidium cattleianum Sabine, 1821), butiazeiro [Butia capitata (Mart.) Becc., 1916], caquizeiro (Diospyros kaki Linnaeus, 1753), cerejeira-do-mato (Eugenia involucrata DC., 1828), goiabeira [Psidium guajava (Linnaeus, 1753)], goiabeira-serrana [Acca sellowiana (Berg.) Burret, 1941], nespereira [Eriobotrya japonica (Thunb.) Lindley, 1822], pessegueiro [Prunus persicae (L.) Batsch, 1801], pitangueira (Eugenia uniflora Linnaeus,1753) e uvalheira (Eugenia pyriformis Cambessèdes, 1832). Os frutos foram coletados e transportados para o laboratório, onde foram individualizados e determinados os seguintes parâmetros: índice de infestação das moscas, índice de parasitismo e frequência de indivíduos por espécie de parasitoide. Foram constatadas duas espécies de Tephritidae, Anastrepha fraterculus (Wiedemann, 1830) (90,5 por cento) e Ceratitis capitata (Wiedemann, 1824) (9,5 por cento) e duas de Lonchaeidae, Neosilba zadolicha McAlpine & Steyskal, 1982 (87,8 por cento) e uma espécie ainda não descrita, referida como Neosilba n. sp. 3 (12,2 por cento). Anastrepha fraterculus é a espécie mais abundante nos dois municípios, sendo constatada na maioria das frutíferas coletadas. Caquizeiro e goiabeira foram os hospedeiros que apresentaram o maior índice de infestação por C. capitata. Quanto às espécies de Neosilba, a maior infestação ocorreu em frutos de goiabeira-serrana. Dos parasitoides emergidos, foram identificadas três espécies, sendo duas de Braconidae, Doryctobracon areolatus (Szépligeti, 1911) (52,6 por cento) e Opius bellus (Gahan, 1930) (27,5 por cento) e uma espécie de Figitidae, Aganaspis pelleranoi (Brèthes, 1924) (20,0 por cento). Doryctobracon areolatus foi o parasitoide mais frequente na maioria das frutíferas amostradas, com exceção da pitangueira e cerejeira-do-mato em que predominou O. bellus, e em pessegueiro com predomínio de A. pelleranoi.

Frugivorous flies (Tephritoidea) are the main pests in temperate-zone fruit crop in Brazil. The objective of this research is to evaluate the infestation of these flies and the incidence of their parasitoids in fruit trees from 2007/08 and 2008/9 crops in Pelotas and in Capão do Leão, located in the south of Rio Grande do Sul. Fruits were collected from yellow guava and red guava (Psidium cattleianum Sabine, 1821), pindo palm [Butia capitata (Mart.) Becc., 1916], persimmon (Diospyros kaki Linnaeus, 1753), wild cherry (Eugenia involucrata DC., 1828), guava [Psidium guajava (Linnaeus, 1753)], feijoa tree [Acca sellowiana (Berg.) Burret, 1941], medlar [Eriobotrya japonica (Thunb.) Lindley, 1822], peach [Prunus persicae (L.) Batsch, 1801], surinam cherry (Eugenia uniflora Linnaeus,1753) and (Eugenia pyriformis Cambessèdes, 1832). The fruit was collected and transported to the laboratory, where the following parameters were individually determined: fly infestation rate, parasitism rate, and its frequency per parasitoid specie. It was found two species of Tephritidae, Anastrepha fraterculus (Wiedemann, 1830) (90.5 percent) and Ceratitis capitata (Wiedemann, 1824) (9.5 percent) and two of Lonchaeidae, Neosilba zadolicha McAlpine & Steyskal, 1982 (87.8 percent) and a species not yet described, called Neosilba n. sp. 3 (12.2 percent). Anastrepha fraterculus is the most abundant species in the two cities and it was detected in most fruit crops collected. The persimmon and the guava were the hosts that showed the highest index of C. capitata infestation. Regarding to the species of Neosilba, the highest infestation occurred in fruits of feijoa tree. From the emerged parasitoids, it was identified three species two of Braconidae, Doryctobracon areolatus (Szépligeti, 1911) (52.6 percent) and Opius bellus (Gahan, 1930) (27.5 percent) and a species of Figitidae, Aganaspis pelleranoi (Brèthes, 1924) (20.0 percent). Doryctobracon areolatus was the most frequent parasitoid in most sampled fruit trees, except for surinam cherry and wild cherry, where O. bellus was predominant and for peach, A. pelleranoi.