Acoustical Methods for Detecting Internal Infestation of Mango Pulp Weevil (Sternochetus frigidus Fabr.) on Raw Mangoes (Mangifera indica L.)

Abstract

Since 1987, mango pulp weevils have been slowly infesting mango plantations in Palawan. It started from the southernmost town of Bataraza and has reached the southern part of Puerto Princesa City. However, the northern part of the province is still uninfested (De Jesus, 2000). The province of Palawan has been placed under quarantine to prevent the spread of the insect to other mango producing areas of the country (De .Jesus, 1998).

The mango pulp weevil (Sternochetus frigidus Fabr.) is a small hard-bodied insect which infests mango fruits. The adult female lays its eggs on a fruit when it is about the size of a chicken egg. The eggs hatch and the larvae bore into the fruit where they undergo development, from larvae to pupa to adult, in the span of 32 days. The adult remains inside for another 37 days. Seventy percent (70%) of the adults exit the fruit by boring a hole directly underneath the pupal chamber. No published studies have yet been done on the behavior of the insect outside the fruit.

Acoustical detection methods have been done on fruits such as papayas and mangoes. These were used to detect the presence of fruitflies (Hansen, 1988 & Sharp, 1988). The instruments used reached an accuracy of as high as 80%. However, the detection method relies on the feeding sounds and not on the actual movement of the insect. This project aims to develop an instrument that will detect the presence of mango pulp weevils using acoustical methods, and to interface the instrument to a microcomputer. The instrument will rely on the movement of the insect and not on its feeding sound.