Do you see the white dots on the heads of the Beetles?
These are the eggs of a useful parasite – the Tachinidae fly Istocheta aldrichi . When the eggs hatch, the larva from its first days will feed on the beetle. This cycle allows us to naturally lower the beetle population in the vineyard and avoids us having to treat chemically.
Since 2020, our strategy has been to understand the behavior of this fly in order to promote an environment conducive to its retention in our vines. The Phacelia that we sow each year in the majority of our fields also attracts the Tachinidae fly Istocheta aldrichi. This fly feeds on the pollen of the phacelia before laying its eggs on the beetles.
Phacelia is very beautiful and also very useful! It is an integral part of our sustainable farming methods.
LIFE CYCLE OF THE TACHINID FLY ISTOCHETA ALDRICHI
This fly, barely smaller than a housefly, emerges in its adult form from its pupa in late spring around mid-June. It feeds on nectar from flowers in its environment.
The Tachinidae fly Istocheta aldrichi.
Around the end of June when the Japanese beetles emerge from the ground, this fly (I. aldrichi) begins laying its eggs just behind the Japanese beetles' heads (on the prothorax, pronotum) until early August.
Two Japanese beetles in the Vineyard on which we can see several Tachinidae fly eggs (white dots).
The egg hatches shortly after being laid. The larva enters the Japanese beetle and feeds on the inside of the beetle (parasitism). Within a few days (about 5 days), the Japanese beetle dies. The fully mature larva forms its pupa in just a few hours.
The larva stage on the left, then the pupa stage on the right. The pupa is the intermediate stage between the larva and adult fly stages.
The pupa will remain inside the Japanese Beetle's shell (mummy) until the following spring when it will emerge as an adult (fly). Then it will begin its life cycle again.
The egg hatches and the larva enters the Japanese beetle where it will remain until the following spring in the pupal stage.
BALANCE ACHIEVED IN THE VINEYARD BETWEEN THE PEST AND THE PARASITE
Since 2014, populations of the Tachinidae fly have increased exponentially in the Vineyard, which has contributed to the considerable reduction of populations of the Japanese beetle. We note that a balance between the pest and its parasite is currently being reached at the Vignoble de l'Orpailleur.
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THE FRUITS OF OUR 25 YEARS OF RESEARCH AND DEVELOPMENT WITH AG-CORD AND CHARLES VINCENT. Charles Vincent worked from 1983 to August 2021 as a researcher in agricultural entomology for the Horticulture Research and Development Centre of Agriculture and Agri-Food Canada in Saint-Jean-sur-Richelieu, Qc. In this capacity, he collaborated for 25 years with Orpailleur and Co-Lab R&D. He is currently a scientific consultant, notably in writing popular texts on agriculture, and in producing podcasts related to agriculture and the environment.
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