Agronomy academics seek biological alternative to control the plague that attacks blueberries

18/05/2015

According to the project director, Dr Pedro Casals, professor of entomology, the idea aims to find and develop an alternative method to chemical products.

"The problem is that Proeulia is an insect that is called quarantine, that is, it can not accompany our exports in any case. Therefore, the main objective is to optimize the conditions for the operation of Apanteles (micro wasps) on the Proeulia. In other words, to optimize its controlling action on Proeulia, then we must know the intimacies of the micro wasps, in terms of its location in winter, how it looks for the host, how and when it parasitizes it, that is, fundamental data to be able to raise these insects, release them and finally deliver them to the producers"Casals explained.

The project that started the 2013 and will culminate the 2016, considers around 186 millions of pesos, of which FIA finances 156 million and the University contributes 40 million between pecuniary and non-pecuniary contributions.

The relevance of this research is that of all the blueberry production that leaves Chile, approximately 50% is rejected because it contains Proeulia spp.

In this sense, Dr. Casals stated that, "This insect is native to Chile, therefore there are not many studies about it, hence the need to deepen the research related to this insect, which originally was adapted to the conditions of native flora, living Coihue, Hualle or Maqui, but when we introduced the berries and the vine, this insect had another food source, preferably adapting to the blueberry".

This research has significant data determined in a previous work developed by the academic and whose results have served as the basis for this new initiative. "Years ago, together with the SAG, we presented to the European Union a project to verify some aspects of biology, among which were the thermal requirements and also the biological cycles during the season and the presence of this insect in certain stages of development of the cranberry. Therefore, the current work is like the continuation. We determine what is the population dynamics, what are the relations with the hosts, what happens with this insect at different times of the year and we were even able to develop a mathematical model based on 10 degrees, this means that insects need to accumulate a certain number of days on certain minimum temperature, the threshold, this because the insects can not regulate the temperature and depend on the external conditions for all their metabolic phenomena«.

«The Proeuia spp needs a temperature 5,8 degrees to begin with its reproductive activities and its larvae are the ones that cause the greatest problem in the ports of embarkation, because the damage in the fruit is not more than a few small holes in the fruit or folds in the leaves , but if the presence makes it an insect of quarantine interest", Said Dr Pedro Casals.

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The studies have been developed mainly in the Eighth Region, but also in the southern part of the Seventh Region, where it has been possible to detect that there are several natural enemies of Proeulia. "With this project we detected that there is almost an 40% of insects that are natural enemies of Proeulia ssp, and from that set we chose which were the most promising in terms of high percentage of parasitism and also ease of breeding them. Then we detected there is a micro wasp of the genus Apanteles, which parasitizes lepidopteran larvae and in particular has a great relevance in the depression of Proeulia populations, therefore it is a great biological controller", Said Casals, who said that currently they are in the matter of raising Apanteles and that other elements have appeared within the biological system that could be of interest to control the Proeulia.

"In addition to the Apanteles, we found the Tricrogram that is a small micro wasp that parasitizes Proeulia eggs, which are exposed on the surface of the cranberry leaves, then this micro wasp is able to find the eggs and embed their micro eggs and finally eliminate the Proeulia. The Apantele that attacks the larval stage of Proeulia and is a little larger than the Tricrogram. Then we have breeding and we are releasing Apanteles in confinement, that is to say at the laboratory level, but the idea is to see what happens with the biological control and to prospect the necessary times to see when there is mortality product of parasitism", Casals pointed out.

Source: Chillán Online