ABSTRACT
The effects of the egg density of Diaphania hyalinata (L.) on several biological parameters of Trichogramma exiguum Pinto & Platner and T. pretiosum Riley were investigated. For that, 24h-old egg masses were isolated in glass tubes (15 replicates; 1 egg mass = 1 replicate), and offered to parasitization by a newly-emerged female of T. pretiosum or T. exiguum 24h at the proportion of one female to 5, 10, 15, 20, 25, 30, 35 and 40 eggs of D. hyalinata. The following parameters were evaluated: number of parasitized eggs, number of individuals per egg, viability and sex ratio. Trichogramma exiguum parasitized more eggs than T. pretiosum when more than 25 eggs were available per female. The percentage of emergence was satisfactory to T. pretiosum in densities up to 15 eggs/female and up to 20 eggs/female for T. exiguum. The number of individuals per egg was not statistically different in both species except in the density of 25 eggs/female. It can be concluded that T. exiguum performed better than T. pretiosum at larger clutch sizes, as T. exiguum parasitization capacity increased as a result of the size of the host clutch size.
Subject(s)
Clutch Size , Hymenoptera/physiology , Lepidoptera/parasitology , Ovum/parasitology , Animals , FemaleABSTRACT
O parasitoide Lixophaga sp. (Diptera: Tachinidae) ocorreu em lagartas de Diaphania nitidalis (Cramer, 1782) (Lepidoptera: Crambidae) em plantio comercial de abóbora no Estado do Espírito Santo, Brasil. Não há registro de Lixophaga sp. parasitando Diaphania sp. na América do Sul e mesmo os registros para hospedeiros deste gênero são poucos. A caracterização morfológica dos adultos foi feita no Departamento e Zoologia, Instituto de Biociências da Universidade de São Paulo, Brasil. Das lagartas coletadas em campo, 26,2% estavam parasitadas, obtendo-se uma média de 2,2 pupas por lagarta e viabilidade de 14,3%. Esse parasitoide mostrou ter potencial para o controle de D. nitidalis.
The parasitoid Lixophaga sp. (Diptera: Tachinidae) occurred in larvae of Diaphania nitidalis (Cramer, 1782) (Lepidoptera: Crambidae) in a commercial pumpkin plantation in the State of Espírito Santo, Brazil. This is the first report of Lixophaga sp. parasitizing Diaphania sp. in the South America, and there are few reports concerning hosts of this genus. The morphologic characterization of the adults was made at the Department of Zoology, Institute of Bioscience, of the University of São Paulo, Brazil. Of the larvae collected in the field, 26.2% were parasitized, with an average of 2.2 pupae per larva and a viability of 14.3%. This parasitoid presented potential for the control of D. nitidalis.
