Electromagnetic wave and Microwave heating: an eco-compatible solution to control Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

Abstract

Rhynchophorus ferrugineus (Oliver) (Coleoptera: Curculionidae) is the primary pest of palms. Although several methods are used for its control, there is concern that insecticidal treatments can cause substantial environmental pollution. Therefore, the use of electromagnetic waves (EMWs) or microwaves (MWs) to control R. ferrugineus is an attractive alternative option. Microwave heating is increasingly used to manage a wide variety of agricultural and forest pests because it induces thermal death in insects that have a thermal tolerance lower than that of the host matrix. In this study, EMWs (360 Hz, 100 W) applied for 60 min caused 100% mortality of adult RPWs but had no effects on larvae. Microwave heating (2.45 GHz, 500 W) caused 100% mortality of adults in 4 min, whereas larvae required MW heating for only 40 s to achieve 100% mortality. The brain of adult R. ferrugineus was the most damaged region following EMW exposure, with severe damage to the neural cells after 60 min. The neural bundles were broken, and the granular cells were scattered. Microwave exposure affected the cuticle and muscles in adult R. ferrugineus after 4 min and the midgut, cuticle, and muscles in larvae after 40 s. The gut epithelium separated from the basement membrane and became highly vacuolated, almost disintegrating. The cuticle was reduced with separated layers, and muscle fibers were also affected. This work confirms that EMWs and MW heating are promising, ecocompatible methods to fight the spread of R. ferrugineus.