In recent years, the presence of aphids in crops has been the subject of a change in attitude. If previously the presence of the insect set in motion an eradication process, we now measure the extent to which its presence is harmful and compromises future yields before intervening. Again, operations are targeted to control the problem where it is damaging.
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This change in integrated pest management is a good reflection of the evolution of knowledge and, by extension, the type of intervention in the fields, notes Annie-Ève Gagnon, researcher and entomologist at the Saint-Jean-sur-Richelieu R&D Center for Agriculture and Agri-Food Canada. The last general meeting of the Société d’entomologie du Québec in October highlighted the interactions of insects with their environment, which is much more complex than previously perceived. Insecticide applications have very broad effects that affect fauna, flora and insects. “There are more studies to understand what is happening above ground, but also below,” notes the researcher.
This understanding of the interactions has led to a change in the way IPM is carried out, as well as a search for alternatives. Crop health is no longer put in opposition to the presence of insects. “We no longer put biodiversity and cultures back to back,” summarizes Ms. Gagnon. Agricultural practices have diversified to control insect populations, but also the environment has shown more openness to different methods and another perception of insects.
As Ms. Gagnon explains, insects are now seen as an indicator of a deeper problem, a symptom rather than a cause, in the face of stressors that affect crops. It is therefore a holistic approach to biodiversity, which tries to see the systems as a whole that holds together. The challenge that arises is to better understand these systems.
This approach implies that the research teams work more in complementarity. “There are now a lot of soil conservation research projects and a lot of teams working in complementarity to study the different facets and be better equipped to move towards more resilient crops,” says the researcher.
The objective is to find a more sustainable balance than pesticides while respecting an acceptable economic threshold for producers, which may go more towards a stabilization of insect populations than a decline in populations.
The lessons of organic
This change in attitudes is linked to biological control in organic crops, which has made it possible to verify the effectiveness of other types of intervention than pesticides. Three methods have been developed over the years, such as conventional control by introducing a control agent, flooding of trichogramma greenhouses, or biological conservation control. In the latter case, attempts are made to encourage the presence of predators by planting floral resources in strips and mulches, recreating a more diversified system. “We try to prevent the explosion of harmful insect populations in vulnerable environments such as monocultures. We’re back to basics. »
The way aphids are seen is a good example of the change in perception, believes Ms. Gagnon. “Before, we panicked when we saw aphids, which is a predator that appeared in the 2000s. Over time, producers have been made aware and are more tolerant. We have seen that nature does things right since ladybug populations have increased in response. »
Moreover, entomologists observe that the systems seem to react to the arrival of exotic insects, such as aphids. “There is an adaptation in the environment with a greater presence of predators, and a stability that sets in more quickly than we thought. »
The goal today is to create more resilient systems, since it is impossible to eliminate all pests, which means anticipating future spikes and being proactive rather than reactive. The approach also makes it possible to preserve proven control methods, such as an insecticide, for longer and avoid creating resistance. “It takes time to develop an insecticide, it doesn’t happen overnight, hence the importance of using the ones we have well. »
Studies in progress
Ongoing studies demonstrate the evolution in interventions. Physical control by vibration (in greenhouses) is a new approach studied since it has the advantage of not disturbing the environment. The study of molecular genetics is also growing in order to understand the evolution of insects, just as we seek to understand the effects on insect biology of climate change. Current studies are also trying to develop predictive methods on the life cycle of insects to recommend better interventions in the fields. And that’s not counting the research being done in forestry, pollinators and the problems in insect breeding.
Ms. Gagnon also notes that the next generation is abundant in the field, as demonstrated by the large number of research topics presented at the last annual meeting. “There is a craze, the next generation, it is there”.
The entomological society will celebrate its 150th anniversary in 2023, making it one of the oldest societies in Canada. The anniversary will be marked at its next general meeting scheduled for October 9 and 10, 2023 in Montreal.
