Insect outbreaks occur when new strains/species of insects are introduced into areas where they have no or very few natural enemies. However, eventually nature corrects itself; biological control agents appear and multiply in sufficient numbers to control the invaders. But this new state of equilibrium could take years, and by then, farmers would have suffered heavy losses.
The new coconut scale insect (CSI) devastating coconuts in Batangas, Laguna, Cavite and Quezon has been identified as Aspidiotus rigidus, which is different from the more common Aspidiotus destructor.
The immediate challenge to the CSI outbreak is to arrest/contain the further spread of CSI from the current adversely affected areas to the rest of the country. The idea is to reduce CSI population and slow down its spread in orderto give the time for the insects’ natural enemies to multiply.
Scale insects are naturally preyed upon by wasps,coccinelid beetles, earwigs, and lacewings,and these are also infected by fungi. Our key agricultural research agencies (Department of Agriculture’s Philippine Coconut Authority; University of the Philippines Los Banos (UPLB), and Department of Science and Technology-Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development) are working double time to artificially rear these potential biocontrol agents in great numbers to release them in outbreak areas. Nevertheless, their efforts are relatively puny considering the gravity of the situation. Their efforts should be multiplied ten-fold to make a difference.
Contact vs. Systemic Pesticides
Scale insects are ubiquitous pests on many crops. They are relatively easy to manage/control with commercially available pesticides. In fact, household detergents and oils that are inexpensive and safe to humans and the environment have been demonstrated to be effective against scale insects.
The problem of CSI control is the difficulty and cost of applying pesticides/detergents on tall coconut trees, many of which grow on steep hillsides and in inaccessible places. Fire trucks full of detergents and with power boom sprayers are okay for coconut farms along roads during the dry season, but their reach will be limited.
Thus, the use of insecticides - whether chemical, organic, or botanical in origin, whose mode of action requires physical contact with the insect pest, is constrained by the cost of application. The solution is to deploy the family of insecticides which are systemic (i.e., the active ingredients get into the plant parts and sap). The susceptible insects, which eat the leaves and stems and/or suck the plant sap, die or fail to reproduce.
There are several organic and/or botanical pesticides, which local suppliers/inventors laim as effective against CSI. However,they have yet to demonstrate their efficacy, safety to humans and the environment, and cost effectiveness. Before they can be adopted in massive scale using public funds, the suppliers/vendors must provide the Fertilizer and Pesticide Authority (FPA) proper, scientifically vetted, and reproducible proof to substantiate their claims.
The burden of proof rests with the technology suppliers/vendors. But given the urgency of need, the government should be proactive and determine which among the new organics and botanicals have the most potential. Then, they should facilitate their testing. However, testing all products will be very expensive, and therefore, further verification can be directed to only, say, two or three of the most promising botanical pesticides. To eliminate bias, the government may constitute an impartial panel of scientific experts to identify the products with the most potential.
Among agricultural pesticides, the most commonly used worldwide are the family of chemicals called neonicotinoids. These neonicotinoids attack the nervous systems of insects and cause their death. They are toxic to insects but relatively benign to mammals, including humans. They are effective under very low concentrations and are not persistent in the environment.
Among the neonicotinoids, the newest, safest, and most promising is Dinotefuran, a third-generation formulation, which is Category IV in toxicity. Category I pesticides are the most toxic and persistent and now practically banned worldwide. The FPA certifies only those pesticides belonging to Category II or better.
However, Dinotefuran has not been used on coconut. The most cost-effective mode of application is yet to be determined. Dinotefuran could be applied as aerial spray; incorporated into the soil like fertilizers; or bored into the coconut bark or trunk. Incorporating Dinotefuran into the soil like fertilizer is easy, but more pesticides will be needed; the effectivity is delayed; and the efficacy is problematic. Aerial spraying with airplanes is likewise relatively easy and cost- effective. However, resistance or objections from the rural communities will be strong despite assurances that Dinotefuran is relatively benign to people. Thus, the preferred option for now is boring the insecticide into the coconut bark and trunk.
But neonicotinoids, including Dinotefuran, have a serious drawback — they are toxic to non-target economic insects like honeybees and silkworm. Honeybees, of course, are very important, not so much for their honey, but for their beneficial role in pollinating fruit crops, vegetables, and other crops.
The coconut is naturally cross-pollinated by wind and by other insects like flies and Beetles, so the loss of honeybees will not be serious for the coconut industry.
Trade-off Between Honeybees and the Coconut Industry
The trade-off that need to be resolved, therefore, is between the decimation of honeybees versus the prospective death of the coconut industry upon which millions of Filipino farmers depend for their livelihood. The coconut industry likewise accounts for the lion’s share of our agriculture exports. However, the trade-off need not be taken to the extreme because the conflict could be localized and intelligently managed.
The insecticide will be deployed in a large scale, only in the limited geographical areas where CSI outbreak is severe. As soon as the CSI outbreak is arrested and subsides, the insecticide application will be discontinued. The damage will not be permanent since the honeybee population in nearby untreated areas will recolonize the outbreak areas. Moreover the government can hasten honeybee population build-up by bringing in new farmed beehives. By then, the government program of mass multiplication and dispersal of natural biocontrol agents would have also gotten off the ground.
Trade-off Between Organic and Conventional Coconut Production
The other trade-off that needs to be managed is the loss of the organic status of coconut farms, which supply organic coconut water in the world trade. However, this trade-off is really between public and private goods. The few fortunate coconut farmers and cocowater processors/exporters who receive a premium for organic coconut water need not adopt the use of chemical pesticides and conventional fertilizers deemed most cost-effective by responsible government institutions. They can always use the organic pesticides and/or botanicals offered by commercial providers but at their own cost and risk.
The CSI outbreak need not be the end of the Philippine coconut industry. Just like the Psyllids insect outbreak, which damaged ipil-ipil trees more than a decade ago, nature will take its course, and a new balance between coconut scale insect and their natural enemies will take place. In the meantime, the government can take vigorous measures to arrest/contain the spread of CSI, with chemical, organic, and botanical pesticides, as appropriate. The research agencies should ramp up their scientific activities to identify the most effective natural enemies of CSI, facilitate their mass rearing, and determine their most cost-effective deployment.
But most importantly, the government though PCA, DA, the LGUs, and the state colleges and universities should launch a massive coconut replanting and intercropping program to raise total farm productivity, generate additional employment, and raise the income of coconut farmers.
(written by Dr. Emil Q. Javier. Dr. Javier is the Chair of the Coalition for Agriculture Modernization in the Philippines (CAMP) and a member of the National Academy of Science and Technology (NAST-DOST)