Seletividade de fungos entomopatogênicos a Trichogramma pretiosum Riley (Hymenoptera: trichogrammatidae) e virulência a Bemisia tabaci (Hemiptera: Aleyrodidae

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

The entomopathogenic fungi and the parasitoid Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) can be used, at the same time, in the tomato culture. However, it is still unclear the effects of entomopathogenic fungi on T. pretiosum. Thus, this study aimed to analyze the selectivity of entomopathogenic fungi against T. pretiosum and assess the virulence on Bemisia tabaci (Hemiptera: Aleyrodidae). Two isolates of each of their entomopathogenic fungus Beauveria bassiana (Unioeste 47 and Unioeste 57), Metarhizium anisopliae (Unioeste 43 and Esalq 09) and Isaria sp. (IBCB 367 and IBCB 394) were used. 1) Selectivity to T. pretiosum: the isolates were sprayed at a concentration of 1.0 X 10 9 conidia/mL on cards (1.0 X 5.0 cm) containing Anagasta kuehniella (Lepidoptera: Pyralidae) eggs. The control consisted of sprayed sterile distilled water containing Tween® 80 (0.01%). Two tests were conducted: (a) free choice for parasitism by confining a female T. pretiosum with two cards, one sprayed with the isolate, the other with the control, and (b) no choice, which consisted of sprayed cards prior or subsequent to parasitism. Observations were made in Scanning Electron Microscope (SEM) and Light Microscopy (LM). At (a) the isolates caused repellency to parasitism by T. pretiosum, and at (b) the pre and post-parasitism spraying interfered in the percentage of emerged adults, egg-adult cicle and longevity. At SEM, it was observed conidia attached to females that realized parasitism. At ML, it was observed adult tissues colonized by the isolates. 2) Strategies for implementation: Post-parasitism (A) cards were submitted to parasitism by T. pretiosum and then sprayed with the isolates at 24, 72, 144 and 168 h. Pre-parasitism (B): the cards were sprayed with the isolates at 0, 24, 48, 72 and 96 h and then subjected to parasitism. Observations were made in Scanning Electron Microscope (SEM) and Light Microscopy (LM). In (A) the isolates affected the egg-adult cicle, the emergence and the longevity, while in (B) it was observed changes in the egg-adult cicle, the number of parasitized eggs, the percentage of emerged adults and the sexual ratio. In the immature stages there were no evidence of infection by entomopathogenic fungi (ML). 3) Virulence to B. tabaci: Isolates were sprayed (1.0 X 10 5 to 1.0 X 10 9 conidia/mL) on third instar nymphs of B. tabaci and then evalutions were made on confirmed mortality and the median lethal concentration (LC50). It was observed that the isolates Unioeste 47 and IBCB 367 caused the highest mortality rates (84,1 e 98,6%) and had the lowest LC50 (4,1X10 5 e 2,5 X 10 5 conídios/mL).

ASSUNTO(S)

inseto - controle biológico inseto parasito trichogramma mosca branca tomate - doenças e pragas insects biological control parasitic insects trichogrammatidae bemisia

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