Field releases of Trichogramma cacoeciae (Marchal, 1927) (Hymenoptera: Trichogrammatidae) against the codling moth, Cydia pomonella (Linnaeus, 1758) (Lepidoptera: Tortricidae)

Abstract

The codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), is a key pest of apples in Tunisia and other countries around the world. Various management strategies have been applied to manage this pest including releases of parasitoids. Trichogramma wasps are known as efficient biocontrol agents tested against a large number of lepidopteran pests including C. pomonella. Two inundative releases of Trichogramma cacoeciae Marchal, at the rates of 25 000 and 50 000 parasitoids per ha, were performed when threshold was reached (2 to 3 adults per pheromone trap) in a commercial apple orchard, in 2018. Results indicated the occurrence of three flight peaks registered in the spring, summer and autumn of the growing season. The efficacy of the two release rates in reducing the infestation level of the population of the codling moth was proved herein. Average infestation level of fruits was significantly reduced after of the first release with reduction of about 27% for rate 1 and 22% for rate 2 compared to the untreated control (45%). Likewise, the average percentage of damaged apples was significantly reduced after the second release (23, 18.37 and 43.37 % respectively for the rate 1, rate 2 and the untreated control). The results showed the efficacy of T. cacoeciae parasitoids as efficient candidates to control C. pomonella.

Keywords

• Apple orchard
• biological control
• egg parasitoid
• inundative releases
• lepidopteran pest