Efeitos do ácido bórico no perfil de expressão protéica em Camponotus vittatus (Hymenoptera: Formicinae)

Abstract

Boric acid aqueous bait, in lower concentrations, have been showed efficient for the control of carpenter ants, acting slowly and being well distributed in the colony by trofalaxis, without repellence, and besides this, they don t injury non-target organisms. Because of the prevalence of Camponotus vittatus in residences in Uberlândia-MG and because there aren t almost any works about its biology, physiology and methods for the control of this ant, this study had the objective to analyze the effects that boric acid ingestion can cause in this insect protein expression aiming to support control proposals. The protein profile was analyzed by SDS-PAGE electrophoreses and mass spectrometry and the esterasic profile by electrophoreses and inhibition tests. The results showed that the boric acid changed the expression of many proteins. Two bands were able to generate trypsinic fragments which indicated, after bioinformatics analysis, similarity of one band with the enzyme arginine kinase. About the esterasic profile, two of them had their expression increased in the group treated with boric acid and one was observed only in this group, what put this enzymes as candidates to specific resistance esterases, used by ants as an attempt to detoxification and/or resistance to boric acid. CHAPTER I: There are many types of pesticides used nowadays, however, they generate a big amount of undesirable collateral effects. Because of this, baits are an ideal tool against urban ants: they have a lower toxicity and are easily transported to the nest, being well distributed by trofalaxis. Moreover, they aren t a threat to non target organisms and have a short environmental impact. Acid boric baits have been used in the control of carpenter ants, showing a good effect in low concentrations. Papers retracting how the acid boric acts in ants are inexistent. In order to provide some information on this field, this study aims to analyze the protein profile of Camponotus vittatus treated with aqueous baits of this poison by gel SDS-PAGE and mass spectrometry. The results have shown that the boric acid altered the expression of many proteins. Many trypsinics fragments were obtained from two differentially expressed bands. The first, highly expressed in the Treated Group, failed in display similarity with any protein from public database. Bioinformatics analysis made to the second band, suppressed in the Treated Group, indicated similarity with Arginine kinase (ArgK), an important enzyme in the maintenance of energetic homeostasis in hymenopteros. Probably, the boric acid would be occasioning ArgK suppression and compromising the ATP buffering system work. More conclusive results weren t possible because of the lack of a C. vittatus database. CHAPTER II: The boric acid, a type of inorganic insecticide, has been largely used in ant control. Aqueous baits, in lower concentrations, have been very efficient because they act slowly and aren t repelled by the ants. Esterases belong to an enzyme group that preferentially hydrolyzes carboxyl acid esters. They are classified by their substrate and inhibitor specificity. In insects they are related with the Juvenile Hormone levels, digestive processes and insecticide degradation. This work analyzed the esterase activity of Camponotus vittatus treated with boric acid. The esterases were stained with α and β-nafthyl acetate and classified by inhibition tests. Six regions with esterase activity were detected, denominated EST1 to EST6 and identified as α-β esterases. EST1, EST2 and EST3 were classified as acetylcolinesterases, whereas EST4, EST5 and EST6 were classified as acetylesterases. EST3 was detected just in the acid boric Treated group. EST1 and EST2 showed an increasing expression in Treated group when compared with the Control Group. The presence of EST3 in the Treated group as well as EST1 and EST2 increased expression in this group place this enzymes as candidates of specific resistance esterases, utilized by ants in a detoxification trial and/or an acid boric resistance.