Fighting lanzones’ scale insect with Chilocorus nigrita

MANILA, Philippines – Lanzones  is one of the fruits commonly sold in the local markets of Southeast Asian countries such as Indonesia, Thailand, and Philippines. Due to high perishability, it is rarely found in many Western countries including the US.

While it is known as a food item in the local market with its edible fruit, lanzones is also believed to possess medicinal value. It finds use in treating dysentery and malaria with a decoction of astringent bark, providing remedy to stings using powdered bark; easing diarrhea through tinctures prepared from dried rinds, and giving cure to vermifuge and fever in children by mixing ground bitter seeds with water.

 Amid the potentials of the fruit, lanzones production has not escaped threats posed by various pests and diseases. Sometime between 2007 and 2008, lanzones production was hit by widespread infestation by mussel scale insects that resulted in a significant decline in yield due to death of trees. One of the greatly affected areas in the country was Davao region.

 Mussel scale insects are among the identified pests seriously infesting the lanzones tree during its growth period, thereby adversely affecting production. Feeding on the lower surface of the leaf, scale insects suck the leaf tissues which cause death and foliage abscission. This renders the tree unproductive, eventually leading to its death.

 As a component of an integrated pest panagement (IPM) approach to fight the pest, the Southern Mindanao Integrated Agricultural Research Center based in Davao City collaborated with the Regional Crop Protection Center of Region 11 and the Bureau of Plant Industry–Davao to implement a project involving biological control against the scale insects.

With funding support from the Bureau of Agricultural Research under the DA’s High Value Crops Development Program, the project aims to equip the region’s lanzones growers with information about Chilocorus nigrita and the processes involved for its mass production.

 Also called Black Chilocorus or black beetles, C. nigrita are sub-rounded beetles which are hemispherical in shape. Along with C. circumdatus, Chilocorus spp. are considered as beneficial insects that voraciously feed on mussel scale insects.

The project aims to follow a natural approach in lowering infestations, introducing C. nigrita to lanzones plantations to serve as predators on the scale insects. Observations showed that after a month from releasing C. nigrita in the field, affected leaves had almost returned to normal conditions.

In mass producing C. nigrita, squash was used as a medium and source of feeding material. Coconut scale insects were also reared to serve as the alternate hosts of the predator. Once the scale insects had proliferated, C. nigrita was introduced into the set-up. After multiplying and turning into adults after 42-45 days, the C. nigrita beetles were then released onto the branches or directly on the leaves of infected lanzones trees. Releasing was done early in the morning with a standard of 100 heads per tree.

One adopter of the technology was Enrique Cadayona, an owner of a 10-hectare farm in Calinan, Davao City. Along with the different fruit trees planted in his farm are about 1,000 lanzones trees of duku and native varieties. Upon learning about the technology, he was able to develop his own rearing cages of C. nigrita.

Apart from appropriate pest and disease management strategies, keeping tabs on several factors such as weather, temperature, and vegetation in order to anticipate problems that could affect the crop, and observing proper field sanitation can help the country’s lanzones production get back on track.