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.

In this study a Brazilian granulovirus strain, PhopGV, isolated from the potato tuber moth (PTM) Phthorimaea operculella, was investigated regarding its potential for biological control and in vivo production. The relationship between mortality of P. operculella larvae and virus concentration was determined at different temperatures on potato tubers and susceptibility of P. operculella to PhopGV was also determined on potato leaves. Virulence of PhopGV to P. operculella was not affected by temperatures from 18 to 30°C. The median lethal concentration (LC 50 ) of larvae fed on potato foliage treated with PhopGV was not higher than that verified with larvae fed on treated tubers. Optimal conditions for production of virus-infected larvae were obtained by using the virus suspensions of 41 9 10 5 , 6.3 9 10 5 and 62 9 10 5 OBs ml -1 at 18, 24 and 30°C, which resulted in 32.0, 31.4 and 34.8% of infected larvae collected, respectively. The maximum percentage of infected larvae recovered from tubers was not affected by temperature. However, time for production of virusinfected larvae was longer at 18°C and shorter at 30°C. Persistence of PhopGV was determined on stored tubers and we observed that the virus remained effective for at least two months, causing up to 84.2% mortality of P. operculella at 1 9 10 7 OBs ml -1 . The pathogen was also highly virulent to tomato pinworm, Tuta absoluta, inflicting high percentage of mortality, delaying larval growth and inhibiting pupation. This Brazilian PhopGV strain has potential to control PTM larvae on potato tubers at a broad range of temperature and can be produced in vivo using virus-treated tubers.

Searching for integrated control strategies for the insect-pest

-The colonization of Spodoptera frugiperda J.E. Smith larvae and rice seedlings by genetically modifi ed endophytic bacterium Methylobacterium mesophilicum, and also the possible transfer of this bacterium to inside the larva's body during seedlings consumption were studied. The data obtained by bacterial reisolation and fl uorescence microscopy showed that the bacterium colonized the rice seedlings, the larva's body and that the endophytic bacteria present in seedlings could be acquired by the larvae. In that way, the transference of endophytic bacterium from plants to insect can be a new and important strategy to insect control using engineered microorganisms.

Emamectin Benzoate was registered recently in Brazil to control Chrysodeixis includens (Walker, [1858]) (Lepidoptera: Noctuidae) in soybean. We studied the baseline susceptibility of Mato Grosso populations of C. includes to support Insect Resistance Management programs by standard feeding assays on insecticide-surface of artificial diet. Variation in susceptibility between populations was low. The LC50 values from 11 populations varied between 0.015 a 0.065 µg i.a. cm-2. Based on our results, we propose the discriminant concentration of 2.867 µg i.a. cm-2 of emamectin benzoate to monitor insecticide resistance in C. includes.

Emamectin benzoate has been largely used for controling lepidopterans larvae in grains and fiber crops and, therefore, selection of resistant populations to this pesticide is a real risk if ignored the insect resistance management (IRM) strategies. We studied the susceptibility of Spodoptera frugiperda (Smith, 1797) populations in the state of Mato Grosso - Brazil to Emamectin benzoate as well as a field study about Mode of Action rotation including this compound. Low variations in susceptibility (resistance ratios, 1,01-7,31 fold) were detected among the evalueted S. frugiperda populations. The field study reinforced our monitorings outcome that Emamectin Benzoate controls S. frugiperda and its use in IRM in Mato Grosso is practicable. Susceptibility monitoring should be continuous in order to detect possible increases of tolerance rates not only for this pesticide but also for all compounds used for this pest management aiming to apply early mitigation actions.