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Insects

In small doses

Unesp researchers develop a less toxic and slow acting bait for the control of ants.

eduardo cesarRed Fire Ants prefer fatty foods and are attracted by sulfluramideeduardo cesar

They are not as repulsive as cockroaches nor do they annoy as much as mosquitoes or flies, but, like these insects urban ants are a pest. Carriers of fungi and bacteria, they can contaminate food in homes and restaurants and spread illnesses in hospitals. For this reason, they need to be promptly controlled. The good news in this combat, taken to the front line mainly by housewives and disinfecting companies, is that a couple of biologists from the Social Insects Studies Center of the Paulista State University (Ceis-Unesp), in the town of Rio Claro, have managed to develop an efficient system for the control of ants starting from knowledge acquired during more than two decades of basic research. The insecticide is a “kill the ant” in the form of a bait, a product that the ant takes into the inside of its nest as if it were food. Once inside, as a consequence of the complex system of the ants’ food exchanges – some provide food to the others via regurgitation -, the poison reaches a large number of individuals, annihilating the ant nest.

The scientists’ challenge was to produce a bait that would imitate, with perfection, the ants’ food, because they are animals that are very sensitive and do not allow themselves to be easily taken in. “By way of learning, acquired over a long evolutionary process, the ants are highly specialized in their food and know how to avoid that which does them and their colony no good”, explained the biologist Odair Correa Bueno, one of the study’s authors. For this reason, the attractive element within the bait, one of its main ingredients, would have to be the very components of the insect’s food. “One of the study’s most important aspects was to identify what were attractive, which are  the calling cards of the bait, those best indicated for the composition of the insecticide”, added the biologist Osmar Malaspina, the other member of the duet.

The researchers concluded that, in order to control the existing eight main urban species of ant, responsible for more than 85% of the infestations in the world, they would have to develop different baits. The most disseminated in Brazil is the ant named fantasma (ghost) (Tapinoma melanocephalum), which is attracted by sugary substances. Minute, it measures between 1 and 1.2 millimeters and gained its name due to its black head and part of its whiter body being translucent against the light. Other species, such as the Fire Ant (Solenopsis saevissima) –  which gives a bite mainly on the feet when one steps on the ants’ nest causing intense ardor only relieved when washed with water -, prefers fatty foods. “We perceived that a single formula wouldn’t be efficient because the varied species have distinct food habits and behavior. Thus we’ve developed five formulae with two main active ingredients: one for sugary baits and the other for oily ones”, affirmed professor Odair Bueno.

The main active ingredient for the sweet baits was boric acid and for the fatty ones, sulfluramide. The two substances are already used in baits sold on the market, but the insecticides created at the Ceis laboratories have a difference: the main active ingredients are at a much lower concentration, from five to ten times lower than those existing in commercial baits. This formula makes the baits less toxic and will have a slower rate of action.

“The low concentration is advantageous because it substantially reduces the risk of domestic accidents, such as the accidental ingestion by children or animals, as well as environmental contamination. And the fact of being less toxic does not make the bait less effective than the common insecticides”, advised biologist Malaspina. The researchers pointed out another advantage in the products developed by them. “Baits with high concentrations of insecticides or with inadequate active ingredients kill the ant on its way back to the colony, because the insect carries the product in its mouth or bag, a type of first stomach existing in these animals”, explained professor Bueno. This is not the objective. “We want the ants responsible for food collection, the forager workers, to take the bait back to the interior of the ant hill and to distribute it to the other individuals in the nest, such as larvae, the young and the queens.”

eduardo cesarAn insecticide in the form of a gel eliminates ants in residenceseduardo cesar

The breakdown of the metabolism
“The slow effect of the baits makes the ants be poisoned in small doses or minima, without them perceiving it. In the opposite case, they would stop taking the ‘food’ back to the colony and the efficiency of the product would be zero.” By having distinct main active ingredients, the Unesp baits possess diverse action mechanisms. In the case of the sugar seekers, the boric acid strikes at the ant’s digestion tube, bringing about the degeneration of its stomach and leading to the animal’s death. With the fatty baits, the sulfluramide is absorbed together with the oil used in its composition by a gland located in the insect’s head. This brings about the animal’s death by inhibiting the production of energy in the mitochondria which are the cell structures responsible for this function in the ant’s organism.

A third type of bait, different from all that exist today, is being studied by the group. Its formula will substitute the current insecticides. “We’re thinking of using certain hormones produced by the insects themselves that have the potential to inhibit the development of the larvae or to interfere in the posture of the queens. These are ideal baits. We have already successfully managed to develop the theoretical and experimental framework. In order to begin the applied research, we’re depending upon a partnership with one of the major insecticide manufacturers”, advised biologist Malaspina, who explained why the twosome decided to develop new types of bait: “The conventional methods for controlling insects, which make use of a powder or liquid sprays, don’t work well with ants because they only kill the visible individuals that have contact with the poison. The rest of the population in the colony remains unharmed. When they perceive that some of their members are dying, an unordered dispersion occurs, which very often ends up in regrouping in the form of various other nests”.

Consortium of companies
The research into the development of new baits was able to count upon the support of FAPESP, which financed the studies by way of the Technological Innovation Partnership (PITE) program. With the objective of putting the baits on the market, the biologists sought out partnerships through private initiative. “Our initial idea was to outsource the production. During a year and a half period we searched for a partner, but we didn’t have any success. We wanted to find a company to whom we could reveal the knowledge acquired through more than 20 years of study”, related biologist Bueno. The way out was to mount their own company for the product’s manufacture, named Tapinoma, which was born in Unesp’s Technology Incubator at Rio Claro (Incunesp). It will be responsible for the production of the baits formulated using boric acid. The products based on sulfluramide will be manufactured by Dinagro, an insecticide manufacturer from the city of Ribeirão Preto (SP), a specialist in the synthesizing of this substance. The commercialization will be the responsibility of the Paulista company Vitex Agricultura e Pecuária, a distributor of products for controlling urban pests, which is the partner company in the project.

In total, the consortium of companies will manufacture six products that should be put on the market starting from March of this year. They are merely awaiting final registration with the National Health Surveillance Agency (Anvisa), forecast for the end of February. The line named Formitap will be sold in four formula make ups: AB, with boric acid, in a paste form; AB-MAX, in gel form, for the ants that are located in homes, companies and hospitals; S, of sulfluramide, in a farinaceous form, for garden ants; and S-PLUS, microgranules, also for garden ants. The usage indications for each product are on the packaging label and on a prescription slip for each one.

Monitored nests
The insecticide Simisfor AB-MAX, in the gel formula, will be offered in tubes, of, at the minimum, 30 grams, and will be directed towards firms specializing in pest control. The sixth product, a viscous non-toxic liquid, whose commercial name is Monitap, will be used together with Simisfor by insecticide companies to monitor if there has been a reduction in the number of ant nests in an infected area.  In a hospital, for example, the Monitap could be placed in a nursery or any other place to attract and locate ant nests. The advantage of its application is that, being non-toxic, there is no risk of contamination in sensitive environments.

Confident of success in the business, the researchers estimate that the formicide national market in the urban area moves something in the region of US$ 4 million per year. “Unfortunately, more than half of the commerce is dominated by clandestine firms, who sell illegal products without labeling or the name of the main ingredient and without being registered at Anvisa”, advised professor Bueno. As well as this, part of the baits sold in the country is manufactured starting from the adaptation of foreign products, without taking into account the biology and the diversity of species that occur here in Brazil. In its first year of activity, Tapinoma will have the production capacity of 1,000 units per day of bait in the form of gel, the most sought after on the market, which should cost around R$ 6 per 10 gram tube, about the same price of already existing products. In conformity with the structured forecast of the PITE program, Unesp and Vitex will each receive 49% of the net income from sales, and FAPESP will get the remaining 2%.

As well as the production and commercialization of formicides, the project forecasts a stage for the certification of companies specializing in pests that are going to work with the products. “In the place of one single application, as occurs with the majority of the commercial products, our baits require around eight applications, over a two to three month period, as well as constant monitoring. Thus, the better the knowledge of this methodology on the part of the disinfecting companies, the greater the chances of success in controlling the ant colonies”, underlined professor Bueno.

Urban differences
The knowledge of biology and of the behavior of different ant invaders of urban environments was essential so that the researchers Odair Correa Bueno and Osmar Malaspina could mange to create a new system of ant control. “When we began the PITE project in 2002, all of the basic research had already been done”, advised professor Bueno. “These studies were important because urban ants possess peculiarities that make them different from the other species, such as the existence of more than one queen in the same nest.” The queen is the individual responsible for laying eggs in the colony.

Another peculiarity is related to the manner of reproduction. The majority of the ants breed in full flight, in the so called “nuptial flight”, it so happens that the breeding of the urban species occurs in the interior of the nest itself, very probably in a defensive strategy to avoid exposure to predators. These ants also do not need to construct their nests. They make use of cracks in wood, electrical tubing and hollow spaces behind tiles to form their colonies.

Contrary to the majority of species, the urban ants form single colony populations. The multi-colony characteristic made ants of the same species, but in different nests, dispute the territory among themselves. Urban ants lose the colonial defense and circulate freely between other nests, on average, housing 2,000 to 4,000 individuals, without counting the immature forms (larvae and the young). “Very often the nests communicate among themselves, leaving the colonies extremely populated”, advised professor Bueno. “There are scientific publications about the existence of a mega-colony in Europe, covering Spain, Portugal, France and Italy, which extends for more than 6,000 kilometers along the Atlantic Ocean coastline and the Mediterranean Sea.”

The Project
Development of a control system for ant colonies in urban environments  (nº 02/02967-1); Modality Technological Innovation Partnership (PITE) Program; Coordinator Odair Correa Bueno – Unesp; Investment R$ 114,800.00 (FAPESP) and R$ 84,600.00 (Vitex)

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