Who could believe that the tiny eggs of the dragonfly could be a problem for the all powerful car industry? Nevertheless, after a fly over of dragonflies, it is common practice in the courtyards of the car manufacturers to spray water over the cars. Few people understand why, but the fact is that the eggs of these aquatic insects leave irremovable stain on the paintwork of the cars. Recently a study by Etelvino Bechara and Cassius Vinicius Stevani, of the Biochemical Department of the Chemical Institute of the University of São Paulo (USP), revealed that the damage is chemical: in contact with the hot metal of the car which is exposed to the sun, the eggs of the dragonfly produce a strong acid, similar to sulfuric acid, capable of corroding the protective layer of the paint. Last November, this study won the Abrafati Award (of the Brazilian Association of Paint Manufacturers).
The problem is more frequent from March to May, the time of the flyovers and mating. The dragonflies fly in the direction of the cars, attracted by the light reflecting from their surface – smooth and shiny like the water where they usually lay their eggs -, and there they lay them. Three or four hours afterwards, the damage is visible: opaque stains more or less circular of close to 5 millimeters in diameter, and washing or polishing the car does not help.
A good question
Taken up by General Motors, the problem was taken to Renner DuPont, the manufacturer of the acrylo-methylamine resins that is part of the paint used in the cars. At that time, the press had been highlighting a piece of research done by Bechara about the bioluminosity of fireflies. Consequently, the technicians at Renner looked for the researcher with the obvious question which had been tormenting them: why do the eggs of the dragonfly damage the resin?
Finding the answer would not be easy, alerted Bechara. He and Stevani had never worked with dragonflies and apparently the question had nothing to do with the research that they had been doing. However, they accepted the challenge: they attacked the problem with a very specific study – The Chemical Nature of the Damage Caused to Resin Films by Dragonfly Eggs: a Problem of the Car Paint Industry -, financed by FAPESP as Stevani postdoctoral project.
Besides two years of work, the research demanded the ability to bring together various areas of knowledge. “The first step,” tells Bechara, “was to look for information about the insects.”
Research which involved the Zoology Museum and the Institute of Biosciences of USP, showed that they needed to understand the behavior of the dragonflies. Aquatic and predatory, they live in regions of clean water, but can be found a few kilometers from lakes, rivers and dams – the type of place, unfortunately, where the car manufacturers are located in the São Paulo region of ABC (The industrial suburbs of São Paulo). During the larva phase, the dragonflies feed on aquatic insects, tadpoles and even small fish – and they serve as food for larger fish. Adults eat bees and other winged insects, including those of their own species. They are also one of the favorite foods of birds. To understand what happens with the paintwork of the cars, it was important to discover that the dragonflies were attracted by the light reflecting from the surface of the water where they deposited their eggs. That is to say: everything suggested that they confused the shiny surface of the cars with a small lake.
Other curious details came to the surface. The dragonflies copulate during flight and, as fertility only occurs during the laying phase, the male pursues the female until she lays her eggs, so as to avoid the interference of another male. The dispute for reproduction is unyielding. The male has an arm which he can use like a spatula to eventually remove the sperm already deposited by another. For this reason, after mating, it is common to see the male holding the female by the neck with a stomach pincer until she lays the eggs.
Another avenue of research was the study of the composition of the acrylo-methylamine resin. Widely used in the finishing of car bodies and also of household electrical goods, it forms a protective layer over the paint, like a varnish. In this way, it confers greater durability and hardness on the paintwork, as well as resistance to heat and other risks. An analysis of the chemical structure of the polymer, however, showed its main weak points. “The resin can be attacked by acids, light, enzymes present in eggs or free radicals,” says Stevani.
Knowledge of this data led the researchers to three hypotheses to explain the effect of the eggs on the resin. The damage could be photochemical: some substance present in the eggs could be capable of absorbing sunlight, causing the degradation of the resin.
Another possibility would be that of microbiological damage: the organic material which makes up the eggs – a protein gel which guarantees protection and serves as a food stock for the embryo when the egg hatches – it could act as a substrate for the development of fungi, capable of damaging the polymer. The third hypothesis was of chemical damage: some acid substance present in the eggs could be responsible for the transformation of the resin in such a way that the acid works as a corrosive agent in the area of contact of the egg.
Due to the sensitivity of the resin to an acid substance, the suspicion of chemical damage was the most likely right from the beginning. Also, a relatively casual occurrence – acid rain that fell in Sumaré (SP) – made them pursue this hypothesis with more conviction. “Once again we were sought out by Renner DuPont, who invited us to visit the Honda plant in Sumaré to analyze the damage which had occurred to their cars”, says Bechara. The pH of the rain collected was 3 – a level of acid much higher than the rains of the capital which were around pH 4.5 – and it was rich in sulfuric, nitric and hydrochloric acids as well as organic compounds. What caught their attention was the similarity between the damage done by the acid rain and that of the dragonfly eggs. From that point onwards the researchers concentrated on studying the effects of various acids on panels covered with automobile paint, provided by Renner DuPont, and to comparing them with the damage produced by the dragonfly eggs.
Captured on the Tietê
To obtain the necessary eggs for the experiments, Stevani set out to hunt dragonflies. He traveled to Novo Horizonte (SP) during the period of the species’ egg laying – between March and May – and planned a boat adventure within the aquatic vegetation of the river Tietê, always between the hours of 11 AM and 3 PM, the most favorable time. Stevani said it was not difficult to collect the raw material for the study: “I held the dragonflies by their wings to identify the females which are easy to identify as the males have a protrusion on their stomach. With a smooth stroke of the fingers on the stomach, the females liberated their eggs which were collected in a test tube containing distilled water.” Of the insects captured, only two were brought back for the identification of the species – the others were released immediately.
Up until that point, he thought that the eggs contained some acid substance capable of damaging the resin. However, after a chemical analysis he discovered that the reaction of the eggs was not acid, but neutral. This confirmation could have knocked down the hypothesis of the acid hydrolysis of the resin, but in the end helped to reinforce it, thanks to the multi-disciplinary experience of the researchers.
Involved in studies with fireflies and free radicals for more than two decades, Dr. Bechara knew of a process that goes on as soon as the eggs are laid. “The egg absorbs a large amount of oxygen in an activity known as respiratory explosion for the production of oxygenated water, and this reacts with a protein present in the egg to form a polymer which gives greater resistance.” In this process, called sclerotization, the external surface of the egg hardens and darkens – that is to say, it forms a shell. Still believing in the hypothesis of acid damage to the resin, Bechara considered that the acid substance did not need to be present within the egg; it could be formed through predetermined physical-chemical conditions.
The researchers therefore paid attention to the fact that the process of sclerotization of the eggs dropped on the motor cars occurred at a high temperature – which, on a car exposed to the sun, could reach as high as 50° C if it were white or of a metallic finish and 92° C if it were black. They realized, then, that cysteine, an amino acid in the egg, when in contact with oxygenated water, produces cysteic acid, somewhat similar to sulfuric acid.
This reinforced the hypothesis of acid hydrolysis and justified tests which finally proved that: at temperatures equal to or higher than 70° C and in the presence of oxygenated water, the eggs produce cysteic acid, capable of damaging the resin in a form even more intense than that of sulfuric acid.
The tests, which proved and consolidated the hypothesis of chemical damage, involved other researchers. Dalva Lúcia de Faria, of the Chemical Institute of USP, looked into the spectroscopic characteristics of the damage through a technique that permitted the indirect confirmation of the presence of the cysteic acid in the eggs treated with oxygenated water. Maria Teresa de Miranda and Cleber Liria, also of the Chemical Institute, quantified the amount of cysteic acid formed by the eggs. Marcelo Bariatto and Fábio Arraes, of the Integrated Systems Laboratory (LSI) of USP, carried out electron microscope examinations, permitting a visual comparison of the damage done to automobile resins by various chemical agents. There was also collaboration from Jefferson Porto and Delson Trindade of Renner DuPont, who provided the raw materials for the tests and helped with doubts arising about the formation of car resins. At USP, Cleide Costa, of the Zoological Museum and Francisco Cordeiro, of the Institute of Biosciences, identified the dragonflies.
For the public
Though the question asked by the industry has been responded to, Bechara’s work is continuing. Because of the project, he wants to develop a product that consumers could use to protect their cars from the damage provoked by the aquatic insects. For this reason, some of the discoveries of the project remain secret. According to the researcher, the product should benefit mainly dark colored cars, which are more affected since they absorb more light and whose metalwork, in direct sunlight, can reach temperatures higher than 70° C. Therefore, the white and metallic painted cars are rarely affected. According to Bechara, some manufacturers, such as Honda, adopted a palliative solution: “They began covering the cars with polyethylene sheets to protect them while they remained in the yard.” However, besides being of little ecological value, the solution does not solve the problem for the consumer. In Bechara’s opinion, the definite solution will involve an effort by the industry to change the composition of the resin, making it more resistant to the action of acids which will also reduce the damage produced by acid rain – but will not stop the innocent dragonflies from losing their offspring, deceived by an optical illusion.
Originating from an investigation by the industry, the research also has ecological implications. In the end, a long way from water, the dragonfly eggs are not completing their natural cycle: they get lost, which is a hurdle to the preservation of the species, and as well as cars, other smooth surfaces such as asphalt – mainly when wet – , ceramic floors, and windows also produce reflections which attract dragonflies.
For this reason, the discoveries of Bechara and Stevani caught the attention of the Hungarian researcher Gábor Horváth, of the Lorand Eotvos University of Budapest.
Having studied for many years this phenomena of attraction, he helped to clear up what happened on hundreds of oil pools formed in the desert of Kuwait with the explosion of the oil wells during the Gulf War in 1991.
According to the article by Horváth published by the magazine Nature (25th of January 1996, vol. 379, page 303), these brilliant lakes produced an even stronger effect than the surface of water, attracting a large quantity of dragonflies and other aquatic insects as well as birds. In the Fall and Spring, they transformed themselves into devastating traps for species in migration.
The picture us desolating: large quantities of carcasses, where those who managed to escape perhaps lost their last chance to procreate, which has put some species under the threat of extinction.
The Chemical Nature of the Damage Caused to Resin Films by Dragonfly Eggs: a Problem of the Automobile Paint Industry
Assistance to research project
Etelvino José Henriques Bechara and Cassius Vinicius Stevani – Department of Biochemistry of the Chemical Institute of the University of São Paulo (USP)
R$ 12,000 and US$ 8,000