Light trap reduces chemical spraying in Ilocos farmers, raises yield, and benefits the environment

A UV ray-emitting light trap that controls agricultural pests has substantially cut expensive chemical spraying among Ilocos farmers, raising their farm yield, and benefitting the environment with its organic farming-harmonized practice.

The Department of Agriculture’s Ilocos Region Integrated Agricultural Research Center (RIARC) is encouraging farmers’ use of this light trap that has a unique ultra violet (UV) ray wavelength specifically targeted at controlling farm insect pests.

This is more useful in farms than the popular UV lamp in homes that are only intended to ward off mosquitoes and larvae flies.

“This is very cost-effective, and it’s good for the environment because it doesn’t dispose of any harmful residue. Before, farmers thought this light trap is only for monitoring pests. But now they’re finding it effective for pest control,” said Dr. Aida D. Solsoloy, Scientist II at the DA’s Ilocos RIARC.

Agriculture and environment experts have been trying to find alternatives to the use of harmful chemicals to control pest. This is because chemical sprays have been historically linked with occupational hazards or many of farmers’ illnesses.

Chemical sprays are also blamed for environmental contamination, insect resurgence and insect resistance while productivity remains low due to chemicals’ improper use.

The light trap has been successful in raising yield in rice, corn, tomato, eggplant, watermelon, bell pepper, onion, pole sitao, ampalaya, and garlic, a Bureau of Agricultural Research (BAR)-funded study showed.

In specific trial locations in Ilocos Region, highest net monetary benefit was observed at P96,713 for a yield increase of 11.9 metric tons (MT) per hectare in tomato in Piddig, Ilocos Norte; P61,013 for an increase of 7.5 MT per hectare for tomato in Narvacan, Ilocos Sur; and P45,313 attributed to a 6.4 MT per hectare increase in rice in Bangar, La Union.

Farmers’ inability to carry out Insect Pest Management (IPM) has been one of the reasons for the low productivity in small farms.

“We have to keep on finding means to help farmers adopt a pest management system that they will find easy to implement and one that’s economically viable. This will increase their yield and raise their farms’ global competitiveness,” said Dr Nicomedes P. Eleazar, BAR director.

The light trap has successfully reduced harmful chemical spraying.
“The light trap showcased on rice, corn, and vegetables at various towns for two croppings indicated extensive insect pest collection and a marked reduction in frequency of chemical spraying by 35 to 100 percent,” Solsoloy said.

In San Nicolas, Ilocos Norte where farmers used to spray 11 times for eggplant, spraying has been totally eliminated. This makes the light trap compatible with organic agriculture and IPM.

While the device is presently imported from China, it is possible to fabricate or assemble it locally. The casing has once been fabricated locally under Ilocos-RIARC’s supervision while the bulb, which is patented for its lighting technology, was imported from China.


Local government units (LGU) have initially supported Ilocos RIARC in linking farmers to BAR’s project. LGUs have also worked with agricultural technicians on its use.

While there are fears of the UV light’s harm to human, the light trap’s strict use only for night time opens minimal exposure of human to the device.

To help farmers acquire the device, DA or the national government may grant farmers a loan or a subsidy program for the trap. It costs P9,500 in the market.

This may not be affordable for the common farmer that only has 5,000 square meters to tend. But farmers’ cooperatives that form an area of two to four hectares may readily take advantage of its financial benefits. Over four years, it costs only P2.375 per year.

Farmers are still finding this expensive compared to the P250 to P300 per bottle or pack for insecticides. Besides, they are not culturally exposed to using this. But the benefits are immense given an extension work on it.

In a study of actual cost and return on mango production in Paoay, Ilocos Norte, cost of materials input in a 0.2 hectare farm with light trap was lower by 17.6 percent at P23,900 compared to P28,100 in a two-hectare farm without light trap.

Mango yield was significantly higher at 2.1 MT compared to 1.275 MT per hectare in those without the trap.

This resulted in a net income of P33,200, substantially higher by around six times compared to P5,700 without the trap.

Just like popular household insect-killing lamps, the light trap also has a high voltage wire that kills insects as they pass through it.

Despite killing insect pests, the Ilocos RIARC observed that the lamp does not have major injury on insects that are natural enemies of pests. This way, it supports biological control of insect pests.

The study funded by BAR from 2008 to 2010 involved 13 sites in Ilocos Norte; nine sites in Ilocos Sur; four sites in La Union, and five sites in Pangasinan.

Farmers also had a high perception of effectiveness of the device and have expressed “extreme” to “moderate” willingness to buy it.

Among the pests effectively controlled by the light trap is the cecid fly that causes black sunken skin lesions on mango; leafhoppers that pester inflorescence in mango; and twig borers and tip borer in rice and corn.

As an added advantage, collected insects from the lamp may be used as protein source for fish and chickens in ponds and poultry farms. Dr. Aida Solsoloy, BAR-DA