Bioatividade dos extratos aquosos de plantas às larvas da mosca-das-frutas, Ceratitis capitata (Wied.)Bioactivity of aqueous extracts of plants to the fruit fly larvae, Ceratitis capitata (Wied.)

The aim of the present study was to investigate the parasitism of two fruit fly species by different Diachasmimorpha longicaudata strains. Females of two parasitoid strains were reared on Ceratitis capitata or Anastrepha fraterculus that were conditioned in adapted containers. Individual parasitoids were offered 20 larvae for 1 h, using no-choice (20 C. capitata or 20 A. fraterculus) or free-choice (10 of each species) assays. Parasitism was verified by counting scars, and the pupae were classified as non-parasitized (no scars), parasitized (one scar), or superparasitized (multiple scars). Parasitism intensity was compared by evaluating the proportions of non-parasitized, parasitized, and superparasitized larvae. Parasitism intensity and scar frequency were analyzed as functions of host species and parasitoid strain, using chi-square tests. In the non-choice tests, females of both parasitoid strains parasitized the larvae, regardless of host species. However, when the parasitoids had a choice, they preferred to superparasitize A. fraterculus larvae, which are larger than C. capitata larvae. In addition, the female parasitoids parasitized most of the host larvae, regardless of parasitoid strain or host species. However, the frequency of non-parasitized pupae was higher when the offered host species was different from the one in which the parasitoid was reared, and the frequency of superparasitized pupae was higher when the offered host species was the same as the one in which the parasitoid was reared.

RESUMO: Nas cascas dos frutos de pequi já foram identificados esteroides, triterpenos, flavonoides, taninos e saponinas, substâncias promissoras no manejo integrado de pragas. Com base nesta informação, objetivou-se com este trabalho avaliar a ação inseticida de extratos aquosos das cascas dos frutos de pequi a Spodoptera frugiperda. O ensaio foi realizado em campo, utilizando sementes de milho do cultivar 'AL Alvaré' que aos 40 e 47 dias após a germinação foram pulverizadas com concentrações dos extratos de 0,8%, 2,5%, 5% e 10% (v/v). Os extratos foram preparados a partir de cascas dos frutos de pequi que, após picadas, foram secas em estufa (65°C, por 72 horas) e moídas em moinho de facas. Com o pó foi preparado um extrato padrão (10,0%). As demais concentrações foram obtidas a partir deste extrato. Foram avaliadas a intensidade das injúrias causadas pelas lagartas de S. frugiperda em plantas com 43, 46, 50 e 53 dias, utilizando uma escala visual de notas. As pulverizações dos extratos reduziram o número de injúrias provocadas pelas lagartas. A concentração de 5% foi a mais eficiente nesta redução e a de 10% causou fitotoxicidade após a segunda pulverização. O extrato pequi é tóxico às lagartas de S. frugiperda e pode ser utilizado no manejo desta praga. PALAVRAS-CHAVE:Caryocar brasiliense, lagarta do cartucho-do-milho, inseticida botânico .ABSTRACT: Pequi fruit peels contain steroids, triterpenes, flavonoids, tannins, and saponins, compounds that are potentially useful for integrated pest management. As such, the aim of this study was to evaluate the insecticidal activity of aqueous extracts of pequi fruit peels on Spodoptera frugiperda. Field-grown corn plants of the cultivar 'Al Alvaré' were sprayed with extract concentrations of 0.8%, 2.5%, 5%, and 10% (v/v) 40 and 47 days after germination. The pequi peels were chopped, oven dried (65°C for 72 hours), and ground in a grinding mill. The resulting powder was used to prepare a base-line extract (10%), and the other concentrations evaluated were prepared by diluting this extract. The intensity of the damage caused by S. frugiperda caterpillars was evaluated 43, 46, 50, and 53 days after germination, using a visual scoring scale. Application of the extract decreased the amount of damage caused by the caterpillars. The 5% extract concentration was the most effective, while the 10% extract concentration showed evidence of phytotoxicity after the second spraying. These results suggest that the pequi extract is toxic to the S. frugiperda caterpillars and can be used for the management of this pest.

The objective of the present study was to evaluate the ratio of Ceratitis capitata larvae/female of Diachasmimorpha longicaudata that results in the increase of parasitism and the production of females in the progeny. We used 8-day-old copulated D. longicaudata females with oviposition parasite experience and third instar larvae of C. capitata from rearing stock maintained at the Laboratory of Biological Control of Universidade Estadual de Montes Claros (Unimontes). Five densities of C. capitata larvae (10, 20, 30, 40, and 50) were offered to parasitoid females that were at five different densities (1, 2, 5, 10, and 15). The larvae were exposed to the parasitoid females by means of “parasitism units” in adapted cages for 1 hour. Sex ratio, percentage of parasitism, and pupal mortality were evaluated. Both host larval density and female parasite density influenced parasitism, female progeny production, and pupal mortality. Higher female production was observed in the progeny in ratios of 1:1 and 2:1 (larvae/females). Ratios above 1:2 reduced the sex ratio, and ratios below 1:1 caused high pupal mortality rates. The females had higher parasitism activity when they were in groups dividing the same space. Equal ratios of Ceratitis capitata larvae and parasitoid females resulted in improved efficiency in progeny females.

Resumo O objetivo com este trabalho foi avaliar estádios de maturação dos frutos e a influência de temperatura na qualidade fisiológica de sementes de pimenta biquinho. O trabalho foi dividido em dois estudos, sendo o primeiro (I) relacionado aos diferentes estádios de maturação dos frutos com base na sua coloração (verde, alaranjado, vermelho, vermelho intenso e vermelho intenso murcho). Das sementes extraídas determinouse o teor de água e avaliou-se a qualidade fisiológica por meio dos testes de germinação e vigor (primeira contagem de germinação, emergência de plântulas, índice de velocidade de emergência, comprimento, matéria fresca e seca de plântulas). No segundo (II), destinado para determinar a influência da temperatura nas sementes provenientes de frutos vermelhos e vermelho intenso murchos, foram submetidas a diferentes condições de temperaturas: constante (20, 25 e 30 °C) e alternada (20-30 °C), e novamente avaliadas pelos testes de germinação e vigor. A qualidade fisiológica das sementes de pimenta biquinho é máxima quando os frutos são colhidos com a coloração vermelho intenso e vermelho intenso murcho e, as temperaturas constantes de 25 e 30 °C são as mais adequadas para avaliação da qualidade fisiológica de sementes.