Problem Statement: After years of uncontrolled infestation, the highly destructive, sap-feeding rice “Black Bug” Scotinophara coarctata (Fabricius) was considered to be a major threat to the “rice bowl” of the Philippines, Central Luzon and insecticides were widely used to manage it. Widespread yet difficult to observe, this highly invasive species has been found in the Philippines in four major islands to date: Palawan (1982), Mindanao (1992-1997), the Visayas (1998-1999) and Luzon (2005-2006). In Palawan, it damaged over 1,200 ha of irrigated rice fields, prompting the provincial government to procure US $20,000 worth of insecticides. Subsequent reports of Black Bug sightings in six major islands were also attributed to S. coarctata. However, many attempts at controlling the assumed pests using insecticides failed, challenging the authorities to investigate the problem further.

Methods: The Philippine Rice Research Institute under the Department of Agriculture commissioned a consultant taxonomist to collect and determine the identity of the invading rice Black Bugs and their natural enemies from the different islands in the Philippines. Intensive sampling was conducted throughout the outbreak areas in 2006 using light traps and hand collections direct from the rice plants. Museum collections were also loaned and examined. Sub-samples of the collections were dissected, fixed, and examined using scanning electron microscopy and individually compared morphologically to detect species differences. Investigations also gathered information on farmers’ knowledge, attitudes and practices in Black Bug management using a structured questionnaire and, through farmers’ forums, advised farmers and workers on the correct name(s), feeding biology, and control of the black bugs.

Outcomes and Impact: Taxonomic investigations revealed why in many cases it is unnecessary to treat “Black Bug” infestations with insecticides: rather than one species, eleven have now been recognized but only three have been observed to act as pests - (S. coarctata from Palawan and the two S. coarctata group members from Mindanao). The other eight Black Bug species feed on rotting rice leaf sheaths and cause no damage to the rice plant. Furthermore, the populations of these eight bug species are controlled by natural enemies that kill the eggs, nymphs and adults. Most farmers - 85% in 24 of 26 provinces - now adopt the no spray approach for Black Bugs. In addition, because abandoned rice stubble was found to serve as breeding grounds for Black Bugs, ground-level cutting of stubbles, plowing and flooding were recommended to control the Black Bug population.

Lessons: Expert taxonomists have a vital role in advising on pest management. They formulate recommendations for the effective management of pests and reduced dependence on insecticides, helping save money and safe-guard the rice environment and both human and animal health. The Black Bug problem persisted for many years in the Philippines before it was possible to secure taxonomic support. There are still only very few well trained local taxonomist with strong knowledge on the natural history of rice invertebrates. It is therefore of paramount importance to increase their numbers by supporting more training programs in taxonomy while providing better career opportunities and job security.