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| Author(s): |
Fernando Luís Cônsoli
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 1998-01-23 |
| Advisor: | José Roberto Postali Parra |
| Abstract | |
The main goal of this research was to develop an artificial host egg to be useful not only as a container but also as a host, allowing parasitization and development of Trichogramma galloi and T. pretiosum, as well as to improve previously developed artificial diets. Basic research was performed in order to develop an artificial host egg, especially that involving the parasitoid immature development, the antennal and ovipositor sensillar structures of T. galloi and T. pretiosum females related with host recognition and acceptance, the chorionic fine structure of hosts that are commonly parasitized by these species, the parasitization behavior of T. galloi and T. pretiosum on natural and factitious hosts and the selection of plastic membranes to manufacture artificial host eggs. After the selection of this membrane, it was evaluated the best size for the artificial egg and the parasitization pressure (number of females/artificial egg) to get the ideal parasitization for the development of both parasitoids. Thirty-six artificial diets were developed using larval hemolymph or pupal holotissues derivated from many host species as the main component, mixed with different proportions of egg yolk, bovine fetal serum, Grace's medium, protein hydrolisates, yeast extract solution and YeastolateR. It was also tested different ways of extracting pupal holotissues as well as the best pupal stage to do it. The acceptance of the artificial eggs by different T. pretiosum strains was also evaluated. Our results show the physical stimulus from the texture of the plastic egg surface was enough to elicit host acceptance by T. galloi and T. pretiosum. Seven to eight and 9-10 μm thick polyethylene where the most adequated membranes to produce artificial eggs. Artificial eggs of 5 mm in diameter were selected for the in vitro rearing process because they allow the utilization of the highest volume of diet. Hundred percent of parasitization of artificial eggs and the higher number of parasitoid eggs/artificial egg (number ranging from 9 to 87 determined as the ideal number of parasitoids to develop in 1 μl of artificial diet) were found when using 6 females for each artificial host egg. T. galloi and T. pretiosum successfully developed on 11 out of the 36 diets tested for each parasitoid. Diets composed of pupal holotissues from D. saccharalis, egg yolk, bovine fetal serum, yeast extract solution or lactoalbumin hydrolisates allow the best development of T. galloi and T. pretiosum. Parasitoid adults reared on artificial diets showed biological (parasitization capacity), behavioural, and morphological (size) traits comparable with adults emerged from the natural or the factitious hosts. The quality of the artificial diet was afrected by the pupal age. Diets composed with holotissues from aged pupae did not allowed the complete development of the parasitoids. The parasitization of artificial eggs and the immature stage survivorship of different strains of T. pretiosum were quite different. (AU) | |