He is handsome but menacing. Japanese beetle, cand insect pest that feeds on leaves and roots, approaching France, alerts the National Health Security Agency (Anses), Monday, June 13. Because it presents a threat to agriculture, ANSES recommends increased monitoring of the beetle. Franceinfo answers five questions about this enemy of gardens and farms.
1What is this insect?
the Popillia japonica is a beetle with copper-brown wings and a metallic green body from Japan. It can easily be confused with other beetles already present in France, such as the garden beetle. But the Popillia japonica possesses “rows of white bristles under the abdomen” which characterize it, describes the National Research Institute for Agriculture, Food and the Environment (Inrae) in its data sheet. It measures on average 10 mm long and 6 mm wide.
This insect grows from larva to beetle state in usually one year. In cold climates, such as in the northern United States, its lifespan is two years. It spends most of it in immature, egg, and then larva form. Once adult, the Japanese beetle is active from June to September.
2In which areas is it currently reported?
At the beginning of the 20th century, the Japanese beetle migrated to the United States, colonizing the Atlantic coast before spreading west. Then he arrived in Europe where he was spotted for the first time in Italy in 2014, in the regions of Piedmont and Lombardy, then in Switzerland in June 2017, on the Italian border, in the canton of Ticino, specifies ANSES in a report published in May 2022 (PDF). Since then, the outbreak has spread, forcing the Swiss and Italian authorities to switch to a containment strategy over a larger area and no longer over delimited areas.
The Japanese beetle is an insect pest of plants already present in Italy and Switzerland. Its entry into France is very likely and the environmental conditions are favorable to it.
Throwback to the means of surveillance and fight against its establishment ⬇
(1/4) pic.twitter.com/RiFvKWasNP— Anses (@Anses_fr) June 13, 2022
Although it has not yet been detected in France, “there is no reason for him not to enter the territory”, says Christine Tayeh, Scientific Coordinator in the Biological Risk Expertise Unit of ANSES’s Plant Health Laboratory.
The probabilities of seeing it disembark are therefore “high” with a “low uncertainty”. Because the insect “moves easily” and “the conditions of temperature and precipitation are favorable to it”, underlines the expert. Adult, the insect can fly. But he can also “have a hitchhiker behavior, that is to say that it can be transported on any support, not only on the plants on which it feeds”warns ANSES.
3Which plants are endangered?
This beetle will have no difficulty finding food in France, which is home to around a hundred species among the approximately 400 plants it can eat. As a larva, the beetle feeds on the roots of host plants. As an adult, it nibbles the leaves between the veins, giving them a lacy appearance. By nibbling the leaves, the beetle reduces their surface, “which decreases the photosynthetic capacity of plants and therefore potentially their yield”stresses ANSES.
The Japanese beetle can also attack fruits and flowers. Farmers and arborists are concerned by this possible invasion, because the beetle attacks plants grown for food purposes such as plum trees, apple trees, vines, corn, soybeans, beans or even asparagus. It also feeds on ornamental plants such as roses, wild species such as brambles or clovers, or forest species such as plane maple or black poplar.
4Why is ANSES calling for vigilance?
If it is impossible to prevent it from entering France, it is necessary to eradicate it before it colonizes the territory. ANSES estimates that the Japanese beetle spreads at 10 kilometers per year. Hence its alert launched at the beginning of the week and its recommendation to raise awareness among individuals and professionals in the sectors concerned.
“We believe there is a chance of eradicating the Japanese beetle as soon as the invasion begins.”
Christine Tayeh, scientistextract from the ANSES press release
For this, ANSES considers it necessary to deploy surveillance resources “dynamic” in order to detect the insect early and to control it while the population is still “weak and isolated”. “The successful eradications in Oregon and California were done in this context”specifies Christine Tayeh. “If such actions are not taken as soon as possible after the detection of the Japanese beetle, preventing its spread once it has established itself in the territory is likely to be long and have a low chance of success”warns ANSES.
5How to trap these beetles?
ANSES details an operating method which consists of delimiting the infested area and placing traps there “in strategic places, such as along the French border with countries where the insect is present and near key entry points, such as ports or airports, as well as transport networks”, details the agency. These traps contain mixed lures, a combination of sex pheromones and flower attractants.
In addition to the pitfalls, there is the use of synthetic plant protection products and biological control. ANSES also recommends reducing irrigation during the egg-laying period and plowing the soil in the fall to reduce the damage associated with adults and the survival of larvae. INRAe invites anyone who has seen a Japanese beetle to photograph it and report it on its site.