Biorational control of pest insect species in Brazil

Paulo Gimenez will present the Department of Biological Science seminar with a talk entitled,  "Biorational control of pest insect species in Brazil". 

Paulo S. Gimenez Cremonez is a PhD student  from the State University of Londrina, Brazil; currently working at UCT.

Abstract

Since Brazil is a major global player in the export of agricultural goods, it is in the primary interest of the country to find a sustainable balance between agriculture and ecology. A number of pest insects, however, reduce the economic value of commercial goods.  Phytophagous stink bugs damage important crops farmed in the country, such as soybean, maize and wheat. Stink bugs and other pest insects are usually controlled by the usage of neurotoxic insecticides which are not species-specific, insects develop loss of susceptibility, and the chemicals contaminate the environment. The use of selective and less toxic compounds known as biorational insecticides is still very limited. Insect growth disruptors (IGDs) are one of the biorational insecticides that target specific insect hormonal pathways. Our research group has presented promising results using IGDs to combat certain stink bug species in Brazil, namely (1) reduced survival of juveniles in field-based concentrations, (2) morphological changes of external mouthparts during moulting that effectively reduced consumption of the food plant by the bugs. Furthermore, sublethal concentrations of IGDs affected reproductive fitness and morphometric parameters of surviving adults when treated in late juvenile stages. Microscopic investigations have revealed non-uniformity of spermatozoid cysts and a general shrinkage of the nuclei of testicular accessory cells, as well as reduced protein synthesis in the cytoplasm of germ line cells. Recently, the focus of our studies shifted to look at physiological changes that could be linked with different modes of action of a juvenile hormone analogue, which is a promising IGD for stink bugs, as inorganic element disbalance in the haemolymph and changes in the composition of energetic substrates such as carbohydrates and lipids. Studies are planned (1) to investigate specific effects of IGDs in reproductive organs by SEM/TEM analysis and (2) field experiments of the most effective IGDs on stink bugs. In conclusion, different classes of IGDs are effective to suppress stink bug populational parameters under laboratory conditions and may be a good alternative for control strategies.

Tue, 07 May 2019 - 13:00
Venue: 

HW Pearson Lecture Theatre 1, Upper Campus, UCT

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