Food consumption of Chrysoperla externa in different developmental phases of Dysmicoccus brevipes, under laboratory conditions

Estudou-se o consumo e preferência alimentar de larvas de Chrysoperla externa Hagen, 1861 (Neuroptera: Chrysopidae) em laboratório à temperatura de 25±2oC, 70±10% UR e 12 horas de fotofase, utilizando como presa a cochonilha-do-abacaxi (Dysmicoccus brevipes Cockerell, 1893, Hemiptera: Pseudococcidae). Durante a fase larval do predador foram consumidas, em média, 70, 50 e 15,8 cochonilhas do primeiro, segundo e terceiro ínstar, respectivamente, e 10 fêmeas adultas, num total de 145,8 indivíduos. Do número total de cochonilhas, 51% foram consumidos durante o terceiro ínstar do predador. O alto número de cochonilhas consumido demonstra que a C. externa apresenta potencial para ser utilizada no controle biológico da cochonilha D. brevipes.The food consumption and preference of larvae of Chrysoperla externa Hagen, 1861 (Neuroptera: Chrysopidae) larval were studied in laboratory under 25±2oC, 70±10% RH and 12 hours photophase, utilizing the pineapple mealybug (Dysmicoccus brevipes Cockerell, 1893, Hemiptera: Pseudococcidae) as a prey. The results showed that the predator's larval phases consumed on average of 70, 50 and 15,8 mealybugs of the first, second and third instar, respectively, and 10 adult females amounting to 145,8 individuals. It was noticed that 51% of the total number of mealybugs were consumed during the predator third instar. The high number of mealybugs consumed shows that C. externa presents a potential to be utilized in biological control of the mealybug D. brevipes

Bioatividade de extratos de própolis sobre o pulgão Myzus persicae Sulzer (Hemiptera: Aphididae) em couve manteiga

Considering the importance of green peach aphid (Myzus persicae) a pest of various vegetables, the objective of this study was to evaluate the effect of propolis extract on the behavior and mortality of the aphid and to study chemically characterized propolis. Propolis used in this study was collected in Apis mellifera honeybee hives at UNIVASF on the Agricultural Sciences Campus. For the preparation of the extract, 30 g of ground crude propolis per 100 mL of hydrous alcoholic solution (70%) were used during a period of 10 days to yield the stock solution. The same extract was diluted to concentrations of 10, 20, 30 and 40% in distilled water, obtaining the extract ready for use in testing. Bioassays attractiveness (free and no-choice) and mortality were carried out using kale leaf discs immersed in the extract and in the control. Given the results, it was found that the alcoholic extract of propolis in low concentrations exerts pull on the green peach aphid. In over 20% concentrations, however, the same extract repels individuals of that species. The alcoholic extract of propolis is toxic to the green peach aphid, causing increasing levels of mortality as the concentration of the extract increases.Considerando a relevância do pulgão-verde (Myzus persicae) como praga para diversas hortaliças, o objetivo deste trabalho foi avaliar o efeito de extrato de própolis sobre o comportamento e mortalidade desse afídeo. Além disso, caracterizou-se quimicamente a própolis utilizada, a qual foi coletada em colmeias de Apis melífera no Campus Ciências Agrárias da Universidade Federal do Vale do São Francisco (CCA/UNIVASF) em Petrolina, PE. Para a preparação do extrato, foram utilizados 30 g de própolis bruta triturada para cada 100 mL de solução alcoólica hidratada (70%), por um período de 10 dias, obtendo-se a solução estoque. A partir desta, foram feitas diluições para as concentrações de 10, 20, 30 e 40% em água destilada. Foram realizados bioensaios de atratividade (com e sem chance de escolha) e mortalidade, utilizando discos de folhas de couve manteiga tratados com extratos nas diferentes concentrações e testemunha. Diante dos resultados, foi possível verificar que o extrato alcoólico de própolis em baixas concentrações exerce atração sobre o pulgão-verde, enquanto em concentrações acima de 20%, o mesmo extrato repele indivíduos dessa espécie. O extrato alcoólico de própolis apresenta efeito tóxico ao pulgão-verde, provocando níveis crescentes de mortalidade à medida que se aumenta a concentração do mesmo

Parasitismo de ovos de Tuta absoluta por Trichogramma pretiosum em diferentes genótipos de tomateiro

The objective of this research was to evaluate the influence of 2-tridecanone (2-TD) content on three tomato genotypes (TOM-556, HI-1 and PI 134417) in the parasitism of eggs of Tuta absoluta Meyrick, 1917 by Trichogramma pretiosum Riley, 1879. Two experiments were carried out to verify the parasitism in isolated and combined plants. The results in both experiments showed that the percent of parasitism of TOM-556 was significantly higher than the HI-1 and PI 134417. A higher percent of parasitism was observed in all strains when the eggs were placed in isolated plants. It is supposed that the presence of genotypes with different concentration of 2-TD in the same environment may have influenced the parasitic behavior of T. pretiosum.O objetivo deste trabalho foi avaliar a influência do teor de 2-tridecanona (2-TD) em três genótipos de tomateiro (TOM-556, HI-1 e PI 134417) no parasitismo de ovos de Tuta absoluta Meyrick, 1917 por Trichogramma pretiosum Riley, 1879. Instalaram-se dois experimentos para verificar o parasitismo em plantas isoladas e em conjunto. A porcentagem de parasitismo em TOM-556 foi significativamente superior à verificada em HI-1 e PI 134417. Observou-se maior número de ovos parasitados quando contidos em plantas individualizadas. Supõe-se que a presença num mesmo ambiente de plantas com diferentes teores do aleloquímico possa ter influenciado o comportamento parasítico de T. pretiosum

Bioactivity of the organic extracts of Cnidoscolus urens (L.) Arthur (Euphorbiaceae) on the cabbage-caterpillar

The aim of the current study was to identify the phytochemical profile of several different fractions of the ethanolic extract taken from the cansanção-nettle leaves, as well as assess the bioactivity on Ascia monuste orseis. After gathering the plant samples, the species was identified, and the organic extracts were collected after processing was completed in the laboratory. The fractions obtained were as follows: hexane (Hex-F), chloroform (CHCl3-F), ethyl acetate (AcOEt-F) and methanolic (MeOH-F). In the context of the insect, the biological parameters evaluated included the incubation period, egg viability, length of the larval stage and mortality, pupal viability and weight, number of defective adults and leaf consumption. The extracts revealed a large percentage of anthraquinones, coumarins, anthracene derivatives, terpenes and steroids and water-soluble tannins. All the organic extracts were confirmed to exert a negative effect on the embryonic, larval, pupal and adult phases of the cabbage-caterpillar, implying that the chloroform fraction induced 100% mortality in this pierid. It was also possible to verify that all the fractions also affected the feeding behavior of the cabbage-caterpillar, decreasing the leaf consumption by the larvae during the organic extract treatments.The aim of the current study was to identify the phytochemical profile of several different fractions of the ethanolic extract taken from the cansanção-nettle leaves, as well as assess the bioactivity on Ascia monuste orseis. After gathering the plant samples, the species was identified, and the organic extracts were collected after processing was completed in the laboratory. The fractions obtained were as follows: hexane (Hex-F), chloroform (CHCl3-F), ethyl acetate (AcOEt-F) and methanolic (MeOH-F). In the context of the insect, the biological parameters evaluated included the incubation period, egg viability, length of the larval stage and mortality, pupal viability and weight, number of defective adults and leaf consumption. The extracts revealed a large percentage of anthraquinones, coumarins, anthracene derivatives, terpenes and steroids and water-soluble tannins. All the organic extracts were confirmed to exert a negative effect on the embryonic, larval, pupal and adult phases of the cabbage-caterpillar, implying that the chloroform fraction induced 100% mortality in this pierid. It was also possible to verify that all the fractions also affected the feeding behavior of the cabbage-caterpillar, decreasing the leaf consumption by the larvae during the organic extract treatments.