Resumen de Capacidade predatória de Chrysoperla externa sobre Bemisia tabaci biótipo B expostas ao fungo Metarhizium anisopliae

Eunice Cláudia Schlick Souza, Luciana C. Toscano, Wilson I. Maruyama, Genivaldo David de Souza Schlick, Elisa Adriano, André Júnior Andrade Peres

• English

  The objective of this study was to determine the influence of Metarhizium anisopliae on the predatory capacity and functional response of Chrysoperla externa fed Bemisia tabaci B biotype rearing cotton. The stock rearings of B. tabaci B biotype and C. externa were maintained in cages according to preexisting methodologies. Upon hatching, predator larvae were fed on eggs of Ephestia küehniella until their 3rd instar and then fed on whitefly nymphs in density exceeding their intake capacity (150 nymphs/individual). The nymphs were offered on cotton leaf disks (5 cm diameter), 24 hours after the treatments application following: T1: Control (water); T2: M. anisopliae at the concentration of 105 conidia cm-3; T3: 108 conidia cm-3 origined from Metharril® formulation of the 109 viable conidia cm-3 M. anisopliae active principle. The predatory capacity was obtained by the difference between the numbers of nymphs supplied and nymphs left. Five different nymphal densities (130, 160, 190, 220, and 250) were selected for the functional response study. The number of nymphs preyed was recorded after 24, 48, 72, and 96 hours. The M. anisopliae entomopathogenic fungi did not influence predatory capacity of C. externa which ranged from 70.6 individuals at the highest concentration to 87.1 in the control. Conclued that the C. externa predatory capacity was not affected by fungi M. anisopliae concentrations. The predator showed a type-II functional response after 24 hours, and a type-I response after 48, 72, and 96 hours independent from fungi concentrations.

• português

  O objetivo desta pesquisa foi determinar a influência de Metarhizium anisopliae (Metsch) sobre a capacidade predatória e a resposta funcional de Chrysoperla externa (Hagen) alimentada com Bemisia tabaci biótipo B advindas de algodoeiro. Larvas do predador foram alimentadas após a eclosão com ovos de Anagasta küeniella até o 3º ínstar, posteriormente alimentadas com ninfas de mosca-branca, em densidade superior à capacidade de consumo (150 ninfas/indivíduo). As ninfas foram oferecidas sobre discos de folhas de algodoeiro (5 cm diâmetro), 24 h após a aplicação com: T1: Testemunha (água); T2: M. anisopliae na concentração de 105 conídios cm-3; T3: 108 conídios cm-3 oriundo de Metharril® com formulação de 1,0 x 109 conídios cm-3 viáveis do princípio ativo M. anisopliae. A capacidade predatória foi obtida pela diferença entre o número de ninfas fornecidas e as remanescentes e a resposta funcional foi avaliada a partir de cinco diferentes densidades de ninfas (130, 160, 190, 220 e 250), contando-se o número de ninfas predadas após 24, 48, 72 e 96 horas. O fungo entomopatogênico M. anisopliae não influenciou a capacidade predatória de C. externa que variou de 70,6 indivíduos na maior concentração e 87,1 na testemunha. A resposta funcional do predador foi do tipo II, após 24 horas e do tipo I para 48, 72 e 96 horas. A capacidade predatória de C. externa não foi afetada pelo fungo M. anisopliae nas concentrações utilizadas. A resposta funcional para 24 h evidenciou tipo II e para os demais tempos tipo I independente das concentrações de fungo utilizadas. ABSTRACT The objective of this study was to determine the influence of Metarhizium anisopliae on the predatory capacity and functional response of Chrysoperla externa fed Bemisia tabaci B biotype rearing cotton. The stock rearings of B. tabaci B biotype and C. externa were maintained in cages according to preexisting methodologies. Upon hatching, predator larvae were fed on eggs of Ephestia küehniella until their 3rd instar and then fed on whitefly nymphs in density exceeding their intake capacity (150 nymphs/individual). The nymphs were offered on cotton leaf disks (5 cm diameter), 24 hours after the treatments application following: T1: Control (water); T2: M. anisopliae at the concentration of 105 conidia cm-3; T3: 108 conidia cm-3 origined from Metharril® formulation of the 109 viable conidia cm-3 M. anisopliae active principle. The predatory capacity was obtained by the difference between the numbers of nymphs supplied and nymphs left. Five different nymphal densities (130, 160, 190, 220, and 250) were selected for the functional response study. The number of nymphs preyed was recorded after 24, 48, 72, and 96 hours. The M. anisopliae entomopathogenic fungi did not influence predatory capacity of C. externa which ranged from 70.6 individuals at the highest concentration to 87.1 in the control. Conclued that the C. externa predatory capacity was not affected by fungi M. anisopliae concentrations. The predator showed a type-II functional response after 24 hours, and a type-I response after 48, 72, and 96 hours independent from fungi concentrations.