Oleksii Gumovsky: A Field Is Not a Petri Dish. Not Every Experiment Can Be Recreated

In 2017, the Arnika Company established the "Institute of Organic Farming". The Department of Entomology and Phytopathology functions on the basis of this Institute where scientists from various branches of agriculture, namely phytopathologists and entomologists, are engaged in the study of diseases, pest research, and the influence of either on the environment.

We often speak about moths, beetles and caterpillars that spoil agricultural crops, and less often, we elaborate on the insects that protect from those pests. That is exactly why Trichogramma drew the attention of Oleksii Gumovsky, head of the department of entomology and phytopathology, told about the peculiarities of its use. What are your department’s main functions?

Oleksii Gumovsky: Our department specializes in establishing scientific research in the field of organic farming. Its main task is to assess the effectiveness of using plant protection products in organic farming, which is based on modern scientific achievements and world-class techniques.

One of the fields of our activity is the research of Trichogramma, the study of which is planned for a long-term perspective. Currently, we are engaged in three-year research during which we will share the results. What practical value of the Department's research is there already?

Oleksii Gumovsky: Today, among the practical achievements of the department are the accomplishments that have been made through the use of control fields:

• first, to demonstrate the need, urgency and practicality of the use of these fields. In particular, as a comparative factor in evaluating the effectiveness of the use of certain plant protection products;

• secondly, we managed to show that in organic farming these fields yield not less than the experimental ones, i.e., the production fields. Accordingly, this practice does not increase the risk of crop loss in the control fields;

• this practice has made it possible to save on the use of ineffective plant protection products and demonstrated the absence of need for preventive measures in case of appropriate pest monitoring and demonstration of its low density. Based upon the experience gained by the Company and the Institute, how many mistakes are made today when using Trichogramma?

Oleksii Gumovsky: First of all, we are concerned about ignoring Trichogramma species. Unfortunately, in many cases, it is perceived as a universal bio-product, rather than a certain taxonomic category, which includes species that have different biological features. It affects their usage efficiency in one way or another. In most cases, biolabs do not pay attention to species, which is associated with numerous cases of the ineffectiveness of the use of Trichogramma in the bio-method.

A serious mistake may be the inappropriate use of Trichogramma, or its application when the ovipositor has not yet occurred, or when it has already ended.

The third fundamental mistake is the extrapolation of laboratory data to the field. We must remember that the field is not a Petri dish, so, accordingly, not everything what happens in the laboratory can be reproduced in the field. What method is used when applying Trichogramma to crop areas?

Oleksii Gumovsky: Today, Trichogramma is applied in different ways depending on the usability. Trichogramma is applied with the help of a small aircraft or drones. In small areas, it can be done manually. This year we practised all the possible methods, some — on a production scale, others — in a demonstration mode. Our experiments have shown that one of the problems with using Trichogramma is a large number of assumptions and formed ideas that, unfortunately, do not correspond to reality. When using Trichogramma this year, we made sure that the introduction of small aircrafts provides an insufficient share of the trichogrammed eggs that reach the ground. If compared with the introduction of drones that were used in demonstration mode, the number of trichogrammed eggs was four times as high as small aircrafts and other ways (except manual) could provide. What species of Trichogramma are applied?

Oleksii Gumovsky: Nowadays, there are two bio-methods used in Ukraine: Trichogramma pintoi and Trichogramma evanescens. The problem is that the former is much more aggressive in the laboratory culture, it develops faster, and females start egg production sooner. Consequently, T. pintoi supercedes T. evanescens, since it is more active and has a shorter growth period. However, it was demonstrated in Ukraine that the T. evanescens species is more effective. Another nuance is that the sex index, that is, the ratio of males and females, in T. evanescens is much higher for females, and in T. pintoi it is the other way round. Relatively speaking, of 100 individuals T. evanescens the ratio of females and males is 70 to 30, respectively. Our preliminary studies show that it can be adjusted with concentrations, but in order to be sure and have relevant technological recommendations, it will take several years and experiments on different territories. On what crops in the company's crop rotation system do you apply Trichogramma, except for corn?

Oleksii Gumovsky: Of course, the most popular crop from the point of view of the use of Trichogramma is corn. First, this is due to the fact that at the time of the highest injuriousness of the stem borer, this plant reaches two meters of height, and the use of stationary machine sprayers is no longer possible. This works for intensive technology. Besides, chemicals cannot be used in organic farming, so all hopes for pest control lie on Trichogramma.

This year we also applied Trichogramma on soybeans and chick-peas. Surely, technology and efficiency there were different. Soybean affect this year was insignificant, so a small amount was applied. But chick-peas were particularly cared of, because the data from Indian and German researchers warned that it would not be so simple to apply Trichogramma on chick-peas. They note that Trichogramma is rather ineffective on chick-peas, in particular, due to the peculiarities of this crop. It is known that chick-peas leaves are covered with trichoid structures, the so-called trichomes, which secrete liquids, that is, on the tip of such a trichome there is always a small droplet. This droplet consists of a mixture of acids, including oxalic acid, which work as repellents.

They, on the one hand, repel Trichogramma, and on the other hand, if an insect hits a leaf, it immediately sticks and these acids kill it. Trichogramma intends to somehow affect stem borer's eggs on this plant, but it is not even technically possible. What is more, these acids and the structure of the leaf have no such a destructive effect on stem borer caterpillar.

Anyway, this data was collected in other regions, for other species of Trichogramma and, correspondingly, in other climatic parameters. Therefore, we wanted to test it in the laboratory and on the field. Interestingly, experiments in a lab with chick-peas did show the effectiveness of the use of Trichogramma. If there is no alternative, if it is limited to chick-pea plants in high concentration in a confined space, then the affect of the moth eggs occurs. Although, this result does not reoccur in the field. This once again confirms that laboratory experiments cannot serve as a model for industrial practice. Tell more about pest monitoring by means of traps.

Oleksii Gumovsky: This is a complicated and quite controversial matter. First, there are various traps such as pheromone, light, light glue, etc. The principle of their action is based on the fact that males attracted by pheromone, or species of both sexes attracted by light, gather in one place, and one can assume a further process by their number. That is, given a certain number of insects and, possibly, their physiological state, one can assume that the ovipositor will start shortly. Then the time is determined when Trichogramma or other entomophages application is due. Our experience shows that counting on traps is hardly reliable. They cannot be the indicator for plant protection strategy preparation. The quality of pheromones is the weak point of pheromone traps, whereas light traps do not always attract what is on the field.

I worked in Africa for a while, so if you are studying parasitic Hymenoptera, you go to the forest and you have to cover a large area to find what you need. One needs to find the plant that is affected by the insect and the parasite inside this insect. The colleagues studying moths practically never walk in the forest, they turn on a huge lantern at night, being somewhere on campus. And this lantern attracts flies from the surrounding mountains, forests, swamps. They work in one and the same place. This shows how the trap works, it draws everything from everywhere. If you have it full, then this is the performance indicator of your trap, and not of what's going around.

You can have a large number of trapped species and a small number of eggs in the field. In other words, the trap is effective, it informs about the presence and a certain number of adult insects. However, it gives no direct answer to the question of whether oviposition is already in progress.

For the most part, we just go to the field and watch the first ovipositor to appear — this is the very trigger for action. Are there any peculiarities of Trichogramma use on organic crops?

Oleksii Gumovsky: The important point is that as long no chemicals are used, forest belts and other areas bordering on planted areas are not affected by pesticides and thus gain more and more reserve functions. That is, in organic farming it is possible to rely largely on the natural background of entomophages, which, in the conditions of intensive agriculture, is very low or almost non-existent. It means that in this way the forest belt or the nearest meadows can work as a natural bio-factory. For example, this year in the cornfield we found a large number of entomophagous insects, which in general were not considered numerous and the biology of which required further research. Nevertheless, one has to take into account that they were inside the field, that is, they are examples of colonization in one season. In what direction are Trichogramma researches currently under way, what points do experts pay the most attention to and what hope to achieve as a result of their research work?

Oleksii Gumovsky: Today we co-operate with our Moldovan colleagues who have a powerful experience, including practical use, and with French researchers who have started a major project on studying the European Trichogramma, where key research points are determining its genetic variability. In other words, it is studying what different lines represent and the occurrence of cryptic species. In addition, the factors that influence the choice of the host insect will be studied, or to be precise, which moth's eggs will female Trichogramma focus on. Moreover, the research will cover factors contributing to the pest damage by Trichogramma, the features of geographical distribution, the peculiarities of the range of hosts, the number of affected insects and the features of gender balance. It is known that the parasitic Hymenoptera, Trichogramma being one of which, can determine the gender of the brood, which is extremely important for Trichogramma effectiveness since it is the females that affect the pest. Also, together with our colleagues, we create a research program in our territory to combine the results and have significant scientific results in the form of publications. How important are these studies for organic farming?

Oleksii Gumovsky: First, it should be noted that organic farming is a ray of hope for the revival of high-tech approaches to plant protection. After all, the widespread use of chemical means of protection, in particular pesticides, formed in conditions of industrial production, led to the decline of fundamental schools for plant protection, including those that were started by the Academician Volodymyr Pospelov, the Science Academy Associate Member Evhen Zvezoromb-Zubovsky and other researchers of the past. These research schools included a thorough study of the biology of beneficial organisms and pests, an understanding of their role in natural and agricultural lands. In the case of organic farming, it is necessary to take into account all the nuances, to take both pests and beneficial organisms as part of the natural environment, as well as to understand the entire relativity of usefulness and harmfulness of these organisms. Therefore, for the proper use of Trichogramma, it is necessary to know the peculiarities of pest and parasite development, its species, and the factors that influence the affect and the response of the host. Actually, this represents a significant research perspective both for organic farming and for involving scientists in this process. Thank you for an interesting conversation!