Study type: Medical/biological study (experimental study)

A waveguide irradiation chamber for destruction of red palm weevils (Rhynchophorus ferrugineus) inside a block sample of a palm tree trunk. med./bio.

Published in: J Microw Power Electromagn Energy 2003; 38 (2): 137-146

Aim of study (acc. to author)

Irradiation of red palm weevils at the larvae stage inside samples of tree trunks (of healthy and infected palms) at different moisture content levels in order to assess the possibility of utilizing a microwave irradiation technique for practical control of red palm weevils. Design details of the irradiation chamber, techniques followed and the results obtained are presented.

Background/further details

The date palm is the most cultivated plant in the Arabian peninsula and North Africa. The existence of these palms and their multimillion dollar date industry are threatened by a pest known as red palm weevil.
Red palm weevils were inserted at different positions along the centerline of block samples of healthy and infected tree trunks.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Exposure duration: 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 45 min and 55 min without red palm weevil (RPW); 1.2 min and 40 s with RPW
  • power: 700 W (maximum output power of the generators)

Exposure 1

Main characteristics
Frequency 2.45 GHz
Charakteristic
  • guided field
Exposure duration 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 45 min and 55 min without red palm weevil (RPW); 1.2 min and 40 s with RPW
Additional info Reference article: Ali, IA and Al-Jabr 2002. A slotted waveguide radiator for microwave irradiation of multiple samples of RPWs. Submitted for publication Jr. Microwave Power and Electromagnetic Energy
Exposure setup
Exposure source
  • rectangular waveguide section TE10, 8 x 4 cm² cross-section, 10 cm length
Setup The first microwave irradiation period (1.2 min) is for a red palm weevil sample at distance of 3 cm from the leading edge along the central axis. The second microwave irradiation period (40 s) is for a loose sample of an infected tree trunk and a sample of a red palm weevil (larve stage). The whole measurement area was covered with microwave absorbing material.
Parameters
Measurand Value Type Method Mass Remarks
power 700 W - cf. remarks - maximum output power of the generators

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The chamber consists of an aluminium rectangular waveguide with one of its broad sides removed for easy insertion of the block samples of the tree trunk. A rectangular aluminum plate, with the same dimensions as the removed wall section was made to slide-in and cover the tree block sample after its insertion in the waveguide to insure continuity of metallic walls.
Data showed that 100% mortality rate could be obtained with the red palm weevils samples at distances not more than 2-3 cm from the irradiation leading edge of healthy tree block samples and 4-5 cm from leading edge of infected samples. Hot spots were revealed at the leading edge of the tree samples due to high absorption of microwave at these regions.
The data show that only red palm weevils near the outer surface of the palm tree trunk can be efficiently irradiated at 2.45 GHz due to the limited penetration depth at this particular frequency.

Study character:

Study funded by