RESUMO
The cotton bollworm, Helicoverpa armigera (Hübner), was recently introduced in Brazil. During the 2012-2013 harvest, producers reported reduced yields up to 35% on major crops. The economic losses reached US$ 1 billion only in western Bahia, triggering a phytosanitary crisis. The deficiencies in existing taxonomic keys to deal with the morphologically indistinct larvae of H. armigera and the native Helicoverpa zea (Boddie) constrained the detection of new incursions of this heliothine invader. This study explored the identity of heliothine larvae that were found infesting soybean- and corn-growing areas from Roraima state, northern Brazil, through sequences of the mitochondrial cytochrome c oxidase subunit I gene. The inter- and intraspecies sequence variations of DNA barcodes in H. armigera and H. zea were analyzed. The genetic diversity and population structure of the specimens from Roraima and two populations from Piauí and Bahia states, northeastern Brazil, were assessed by adding the cytochrome c oxidase subunit II gene to the analysis. Owing to the lack of studies on genetic introgression for the two species, the suitability of using three different nuclear genes to distinguish the two species was also investigated. The results showed strong evidence that the heliothine larvae from north and northeast of Brazil are conspecific with H. armigera, suggesting that this invasive moth has already crossed the Amazon basin. Surveys in the north of South America should start as soon as possible to monitor the entry or spread of this moth in the Caribbean, Central America, and the United States.
Assuntos
Variação Genética , Proteínas de Insetos/genética , Mariposas/classificação , Mariposas/fisiologia , Animais , Brasil , Código de Barras de DNA Taxonômico , Complexo IV da Cadeia de Transporte de Elétrons/genética , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Proteínas de Insetos/metabolismo , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Dados de Sequência Molecular , Mariposas/genética , Mariposas/crescimento & desenvolvimento , Filogenia , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Homologia de Sequência do Ácido NucleicoRESUMO
Neem derivatives have been widely touted as replacements for pesticides. A feasible replacement of synthetic insecticides in the management of fruit flies could be to use neem products in baits. This study evaluated the bioactivity of neem (Azadirachta indica A. Juss) derivatives in bait for adults of Anastrepha fraterculus (Wiedemann) and Ceratitis capitata (Wiedemann). The estimated LCs50 values for A. fraterculus and C. capitata were 7,522 ppm (18.40 ppm of azadirachtin) and 1,368 ppm (3.35 ppm of azadirachtin), respectively, using an aqueous extract of neem seeds in bait after 10 d of experimentation. No significant differences in the mortality of A. fraterculus and C. capitata adults exposed to baits made from different extracts and neem oil were observed after 3 h or 2 or 6 d; differences among the treatments were observed only on the 10th day of the evaluation. We conclude that neem derivatives applied as a bait spray over citrus plants did not demonstrate a toxic effect on A. fraterculus and C. capitata. The reasons for the low efficacy of the neem bait on Tephritid fruit flies are discussed.
Assuntos
Azadirachta/química , Glicerídeos/farmacologia , Repelentes de Insetos/farmacologia , Inseticidas/farmacologia , Limoninas/farmacologia , Extratos Vegetais/farmacologia , Tephritidae/efeitos dos fármacos , Terpenos/farmacologia , Animais , Feminino , Controle de Insetos , Masculino , Especificidade da EspécieRESUMO
The screwworm, Cochliomyia hominivorax (Coquerel), remains one of the most damaging parasites of livestock in South America, causing millions of dollars in annual losses to producers. Recently, South American countries demonstrated interest in controlling this pest using the Sterile Insect Technique, and a pilot-project was conducted near the Brazil-Uruguay border in 2009. Since molecular studies have suggested the existence of C. hominivorax regional groups, crossing tests were conducted to evaluate mating competitiveness, mating preference and reproductive compatibility between a C. hominivorax strain from the Caribbean (Jamaica-06) and one from Brazil. Mating rates between Jamaican males and Brazilian females ranged between 82 and 100%, and each male inseminated from 3.3 to 3.95 females. Sterile males, regardless of the strain, competed equally against the fertile males for Brazilian females. Jamaican sterile males and Brazilian fertile males mated randomly with fertile or sterile females. No evidence of genetic incompatibility or hybrid dysgenesis was found in the hybridization crosses. Mating barriers should not compromise the use of Jamaican sterile males for Sterile Insect Technique campaigns in Brazil.
Assuntos
Dípteros , Hibridização Genética , Preferência de Acasalamento Animal , Controle Biológico de Vetores , Animais , Brasil , Cruzamento , Estudos de Viabilidade , Feminino , Masculino , Isolamento ReprodutivoRESUMO
Recent fears of terrorism have provoked an increase in delays and denials of transboundary shipments of radioisotopes. This represents a serious constraint to sterile insect technique (SIT) programs around the world as they rely on the use of ionizing radiation from radioisotopes for insect sterilization. To validate a novel X ray irradiator, a series of studies on Ceratitis capitata (Wiedemann) and Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) were carried out, comparing the relative biological effectiveness (RBE) between X rays and traditional gamma radiation from 60Co. Male C. capitata pupae and pupae of both sexes of A. fraterculus, both 24-48 h before adult emergence, were irradiated with doses ranging from 15 to 120 Gy and 10-70 Gy, respectively. Estimated mean doses of 91.2 Gy of X and 124.9 Gy of gamma radiation induced 99% sterility in C. capitata males. Irradiated A. fraterculus were 99% sterile at approximately 40-60 Gy for both radiation treatments. Standard quality control parameters and mating indices were not significantly affected by the two types of radiation. The RBE did not differ significantly between the tested X and gamma radiation, and X rays are as biologically effective for SIT purposes as gamma rays are. This work confirms the suitability of this new generation of X ray irradiators for pest control programs that integrate the SIT.