Bioactivity of neem nanoformulations and extracts of other Meliaceae and their interactions with biological control agents aiming to control Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) Tratamentos Viabilidade de ovos (%) 24 h 48 h ns 72 h ns NC50 aquoso
Due to the reduced host spectrum of the entomopathogenic fungus Metarhizium rileyi, its pathogenicity against different target insects must be assessed to develop biopesticides capable of controlling more than one pest species. This study aimed to evaluate the susceptibility of the pest species Chrysodeixis includens and Spodoptera frugiperda to different isolates of M. rileyi and, thus, determine a possible influence of the host of origin on the pathogenic activity of these isolates. Three isolates [CG1312 (C. includens as original host), CG381 (S. frugiperda as original host) and a new wild isolate (C. includens as original host)] were tested against larvae of C. includens and S. frugiperda, in third instar age, by treatment of surfaces with conidial suspension, under laboratory conditions. Both species were susceptible to the isolates of M. rileyi, with mortality rates of 53-58 % for C. includens and 74-84 % for S. frugiperda. The results suggest that the host of origin may not be determinant in the selection of pathogenic isolates of M. rileyi against these two pest insects.
The influence of Urochloa brizantha (variety Marandu) grazing systems on Mahanarva spectabilis (Distant) and the entomopathogen Metarhizium anisopliae (Metsch.) was studied to understand the benefits of integrated systems in pest management. The pastoral systems studied were: (M) monoculture, (SP) silvopastoral and (ICLF). We assessed the number, per square meter, of alive spittlebug nymphs or infected by M. anisopliae as well as the demanded number of entomopathogen sprays in each pasture system to control the pest. Throughout the experiment period, M. spectabilis was the unique species found. Silvopastoral had a higher number of alive nymphs and a lower percentage of the infected nymphs compared to pasture in monoculture; however, in both systems, only one spray of M. anisopliae was enough to keep the pest below its threshold. In agrosilvopastoral system, there was no spittlebugs infestation. Thus, intensified production systems such ICLF may be more sustainable, considering pest aspects.
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