Soft X-ray can detect mango pest infestation

Soft X-ray can be an effective tool in detecting the destructive mango pulp weevil (MPG) and mango seed weevil (MS) that infest mango fruits.

Moreover, it can complement, or can even replace the irradiation technology without compromising quarantine requirements.

This was found in a study conducted by L.R.I. Velasco of the department of Entomology (DE) and C. dR. Medina of the National Crop Protection Center (NCPC), both at the U.P. Los BañosCollege of Agriculture (UPLB-CA).

The US Department of Agricultural—Animal and Plant Health Inspection Services (USDA-APHIS) requires irradiation treatment of Philippine fresh mango fruits outside of Guimaras owing to MPW and MSW.

The MPW is an insect pest of mango fruits introduced recently in the Philippines. Its distribution, however, is restricted to the islands of Palawan.

To date, the whole of Palawan is under quarantine restriction and fresh mango fruits are not allowed to be brought out of the province.

In the 1980s and 1990s, there was a massive planting of mango trees in Palawan as a result of the Department of Agriculture (DA) program in the province. There are now about one million mango trees on the island, hence, its potential in the domestic and international markets are significant.

In the study done by Velasco and Medina, 240 newly harvested Carabao mango fruits were passed through the Puerto Princesa airport X-ray Heimann Systems hiScan Model 7085-A, the only soft X-ray machine available in Puerto Princesa City.

Using photographs of the X-ray images of mango fruits, selected evaluators of the UPLB-CA NCPC and DE were asked to classify the mango fruits as MPW-free and MPW-infested. Of the 181 photographs, 92 showed MPW-infested fruits.

"In the initial trials using the X-ray images shown in the TV monitor, we were unable to discriminate the insect regardless of the stage of development. However, the damage done by the MPW in the pulp of the mango fruits was readily detected," Velasco and Medina reported.

The study showed that X-ray images can be used for nondestructive detection of MPW-infested mango fruits with a very high level accuracy.

The researchers summed up the merits of the technology thus:

• Soft X-ray can detect and sort MPW-damaged fruits while irradiation treatment only kills MPW and MSW without eliminating damaged fruits. It can also detect other deformities and damages in fruits not visible to the naked eye.

• Soft X-ray is much cheaper (P10 million) and safer to operate than the irradiation technology (P150 million). – Rudy A. Fernandez