RESUMO
Ceraeochrysa claveri Navás (Neuroptera: Chrysopidae) é um predador encontrado em vários agroecossistemas, predando insetos pequenos e de tegumento mole. Seu alto potencial reprodutivo e elevada capacidade de busca o tornam capazes de predar ovos e larvas de
Complaints of severe damage by whiteflies in soybean fields containing genetically engineered (GE) varieties led us to investigate the role of transgenic soybean varieties expressing resistance to some insects (Cry1Ac Bt toxin) and to herbicide (glyphosate) on the population growth and feeding behavior of Bemisia tabaci (Gennadius) MEAM1 (Hemiptera: Aleyrodidae). In the laboratory, the whiteflies reared on the GE Bt soybeans had a net reproductive rate (R0) 100% higher and intrinsic rate of population increase (rm) 15% higher than those reared on non-GE soybeans. The increased demographic performance was associated with a higher lifetime fecundity. In electrical penetration graphs, the whiteflies reared on the GE soybeans had fewer probes and spent 50% less time before reaching the phloem phase from the beginning of the first successful probe, indicating a higher risk of transmission of whitefly-borne viruses. Data from Neotropical fields showed a higher population density of B. tabaci on two soybean varieties expressing glyphosate resistance and Cry1Ac Bt toxin. These results indicate that some GE soybean varieties expressing insect and herbicide resistances can be more susceptible to whiteflies than non-GE ones or those only expressing herbicide resistance. Most likely, these differences are related to varietal features that increase host-plant susceptibility to whiteflies. Appropriate pest management may be needed to deal with whiteflies in soybean fields, especially in warm regions, and breeders may want to consider the issue when developing new soybean varieties.
Aims: Evaluate the insecticidal effect of the aqueous extract of neem leaves on the control of
Costalimaita ferruginea in eucalyptus.
Place and Duration of Study: Entomology Laboratory of the Center for Agricultural Sciences (CCA) of the State University of the Tocantina Region of Maranhão (UEMASUL) between November 2016 and July 2017.
Methodology: Neem aqueous extract solutions were tested at concentrations of 40, 60 and 80%, and the control group treated with mineral water. Leaves of eucalyptus seedlings were immersed in each concentration and individualized in Petri dishes together with the insects. The design was completely randomized with four treatments and ten repetitions, each repetition consisting of a Petri dish with an insect and a eucalyptus leaf. The evaluations were carried out daily, analyzing the mortality of adults, and the leaves were replaced by others submitted to the same treatment and procedure described above.
Results: In the evaluations of 12, 60, 72 and 84 hours there was no significant difference. 36 hours after the implementation of the experiment, the 60% neem concentration resulted in 100% mortality of specimens.
Conclusion: The 60% neem concentration is the most efficient due to its rapid effect on C. ferruginea mortality and economy of raw material for production.
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