RESUMO
Para subsidiar a utilização de táticas de manejo integrado para o inseto-praga Tibraca limbativentris, avaliou-se a compatibilidade in vitro entre o isolado CG 891 de Metarhizium anisopliae e os agrotóxicos utilizados na cultura do arroz irrigado. Os parâmetros avaliados foram crescimento vegetativo, esporulação e germinação em pré e pós-contato do fungo, com duas doses de fipronil, tiametoxam, fenitrotiona, carbofurano, pirazossulfurom-etílico, bentazona, clomazona, glifosato e quincloraque; e uma dose de triciclazol e azoxistrobina. Reduções significativas no crescimento vegetativo e esporulação de M. anisopliae foram observadas para fenitrotiona, carbofurano e azoxistrobina. Observou-se redução na germinação em pré-contato para o agrotóxico azoxistrobina. O valor percentual da germinação alterou a classificação dos agrotóxicos com relação a sua seletividade sobre o entomopatógeno. No entanto, os resultados mostram que in vitro os agrotóxicos fenitrotiona, carbofurano, glifosato e azoxistrobina são prejudiciais ao isolado CG 891 de M. anisopliae.
Searching for integrated control strategies for the insect-pest Tibraca limbativentris, the in vitro compatibility between isolated CG 891 of Metarhizium anisopliae and several pesticides used in the culture of irrigated rice was evaluated. The followings parameters were studied: vegetative growth, sporulation and the germination viability in pre- and post-contact of the fungus for two concentrations of fipronil, thiametoxan, fenitrothion, carbofuran, pyrazosulfuron-ethyl, bentazon, clomazone, glyfosate and quinclorac and one concentration of tricyclazole and azoxystrobin. Significant reductions in the vegetative growth and sporulation of M. anisopliae were observed for fenitrothion, carbofuran and azoxystrobin. The germination in pre-contact was affected by azoxystrobin. The percentage of germination changed the classification of pesticides in relation to its selectivity on the fungus. However, the results show that in vitro, the pesticides fenitrothion, carbofuran, glyfosate and azoxystrobin are harmful to isolated CG 891 of M. anisopliae.
RESUMO
Given the susceptibility of tomato plants to pests, the aim of the present study was to understand how hormones are involved in the formation of tomato natural defences against insect herbivory. Tomato hormone mutants, previously introgressed into the same genetic background of reference, were screened for alterations in trichome densities and allelochemical content. Ethylene, gibberellin, and auxin mutants indirectly showed alteration in trichome density, through effects on epidermal cell area. However, brassinosteroids (BRs) and jasmonates (JAs) directly affected trichome density and allelochemical content, and in an opposite fashion. The BR-deficient mutant dpy showed enhanced pubescence, zingiberene biosynthesis, and proteinase inhibitor expression; the opposite was observed for the JA-insensitive jai1-1 mutant. The dpy x jai1-1 double mutant showed that jai1-1 is epistatic to dpy, indicating that BR acts upstream of the JA signalling pathway. Herbivory tests with the poliphagous insect Spodoptera frugiperda and the tomato pest Tuta absoluta clearly confirmed the importance of the JA-BR interaction in defence against herbivory. The study underscores the importance of hormonal interactions on relevant agricultural traits and raises a novel biological mechanism in tomato that may differ from the BR and JA interaction already suggested for Arabidopsis.
