Chinese paper wasp

Systematic position: The Chinese paper wasp (Polistes chinensis) belongs to the order Hymenoptera and the family Vespidae. As a social insect, it builds complex nests made of paper-like material produced from chewed plant fibers, often found in sheltered areas near gardens and orchards.

Affected crops: This species acts as a polyphagous pest, with a strong preference for high-sugar fruit and berry crops. Primary hosts include grapes, peaches, plums, pears, apples, and figs. They are particularly aggressive during the peak ripening stages of these fruits, causing significant economic losses for growers.

Biology and life cycle: The life cycle begins in early spring when the hibernating queen establishes a new nest. The colony undergoes rapid growth throughout the summer season, producing consecutive generations of workers. The insect undergoes a complete metamorphosis, progressing through egg, larval, pupal, and adult stages, with colony strength peaking in late summer.

Damage and pest status: The primary damage occurs when wasps chew through the fruit's skin to feed on the sugary pulp. These entry wounds not only ruin the fruit but also provide entry points for secondary infections like fungal rots and bacteria. Furthermore, the presence of large wasp populations poses a health risk to farm workers and makes harvesting operations difficult and dangerous.

Effective management strategies include:

• Systematic monitoring and removal of nests near production areas.
• Installation of baited traps containing fermented fruit juices or sugar solutions to reduce worker density.
• Strict orchard sanitation by removing overripe and damaged fruit that serves as a food source.
• Use of exclusion netting over vines and trees during the fruit maturation period.
• Targeted application of insecticides to nest sites, conducted with appropriate personal protective equipment and during periods of low activity.