Natural control for pests and diseases

DUE to its favourable soil and climatic conditions, including its strategic location, the Philippines is suitable for planting cacao trees.

The current estimate of cacao being produced in the country is about 12,000 metric tons (MT).

Based on the Philippine Cacao Road Map developed by the Department of Agriculture and the Cocoa Foundation of the Philippines, Inc., it is projected that the Philippines has the potential to produce at least 100,000 MT by year 2020.

In 2015, however, the International Cocoa Organization estimated a 30 to 40 percent loss in cacao production due to infestations of insect pests and diseases.

Here in the country, the cacao pod borer (CBP), and the cacao mirid bug (CMB) are the more serious ones among the pests affecting the cacao industry.

To address the prevalence of these pests, the De La Salle University (DLSU) spearheaded the study to explore, identify, mass rear, and release biological control agents against the CPB and the CMB.

The cacao pod borer feeds on the cacao bean pulp and the pod’s placenta, causing malformed and undersized beans.

Severe infestation results in small flat and stuck together beans, yellowing, uneven or premature ripening of pods.

The project is being funded by the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development of the Department of Science and Technology (DOST-PCAARRD).

The use of biological control has become a very promising alternative to the more traditional use of chemical pesticides in agricultural pest management.

According to the researchers, biological control uses other organisms in controlling pests.

These can be insects, mites, weeds, and plant diseases, through predation (i.e., organism preying on the pest), parasitism (i.e., smaller organism causing harm on its host organism), or other natural mechanisms.

The project surveyed cacao-growing areas in Quezon, Bicol, and Davao regions that were previously reported with the insect pests as well as the insects and spiders that can be natural enemies or biological control of these pests.

An egg parasitoid, Trichogrammatoidea cojuancoi Nagaraja, was reported to be active against the CPB in Davao del Sur, particularly in areas where there has been no insecticide spraying for a long time.

However, it was not collected during the survey as bananas replaced cacao.

Another possible natural enemy, Paraphylax sp. was found parasitizing CPB in some of the cacao-growing areas in Davao del Sur.

Both of these biological control agents are currently being attempted to be retrieved and collected.

On the other hand, the cacao mirid bug feeds on cacao pods and shoots, inducing tissue decay resulting in non-productive cacao trees.

CMB’s natural enemies include a variety of wasps and spiders, such as the lynx spider, Oxyopes javanus Thorell.

A new species of Erythmelus has been found as a parasitoid of CMB.

Currently, researchers are mass rearing cacao mirid bug for efficiency testing of natural enemies.

Also, a diet is being developed to mass rear the lynx spider.

The study under the Cacao Pest Management Program: Biological-Based Approaches is expected to run for another two years. (jaypeeyap@ymail.com/PN)

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