A research team from De La Salle University (DLSU) has made a potential breakthrough in the fight against cacao insect pests with the discovery of a new species of parasitoid that targets the cacao mirid bug.
Dr. Albert T. Barrion of the DLSU Department of Biology revealed the discovery of a parasitoid called Erythmelus sp., which preys on the cacao mired bug, during the Technology to People (T2P) Media Conference on Friday, March 17 at the Department of Science and Technology-Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (DOST-PCAARRD) Innovation and Technology Center in Los Baños, Laguna.
The Erythmelus sp. is a type of chalcid wasp, also sometimes called a fairyfly, a small (about 0.5 millimeters) insect that lays its eggs on the eggs of other insects. The wasp’s hatched larvae then feed on the host eggs, destroying them in the process.
Barrion said the new species was the first discovered in the Philippines and only the third known in Southeast Asia.
The discovery was a result of a two-year project that started on February 1, 2016 by the Biological Control Research Unit Center for Natural Science and Environmental Research of DLSU funded by DOST-PCAARRD to develop biological controls against cacao pod borer (CPB) and cacao mirid bug (CMB). The two insect pests are considered serious threats to the country’s cacao production, and cause significant losses in yield.
CPB feeds on the cacao bean pulp and the pod’s placenta causing malformed and undersized beans, as well as yellowing or premature ripening of pods. CMB feeds on cacao pods and shoots, causing tissue decay that results in non-productive cacao trees.
The project surveyed cacao-growing areas in Quezon Province, and the Bicol and Davao regions where infestations of the pests were previously reported.
In addition toErythmelus sp., another possible parasitoid, this one targeting CPB, was reported in Davao del Sur, where farmers noticed the pests had declined even though there had been no insecticide spraying for some time. Barrion said, however, that the research team was yet to find samples of the parasitoid, as bananas have replaced the cacao trees in the area.
While searching for that insect, however, researchers found another possible parasitoid, called Paraphylax sp., that appeared to target CPB in some areas around Davao, and are currently in the process of collecting it.
“We do not stop looking for the solution,” Barrion commented, expressing optimism that several more biological agents would be found.
For CMB, other possible natural enemies the DLSU team has identified include a variety of wasps and spiders like the lynx spider. Barrion said researchers are currently raising cacao mirid bugs for testing of natural enemies at the DLSU Science and Technology Complex in Santa Rosa, Laguna.