The approximately 2-hectare mangrove area infested by the larva of ‘tide watching mangrove moth’ was monitored by the team of Biodiversity, Coastal, Wetlands and Ecotourism Research Center–Department of Environment and Natural Resources Region VI (BCWERC-DENR 6) last January 22, 2016. The worms of ‘tide watching mangrove moth’, Aucha velans were found responsible for the drying out and turning brown of mangrove trees that was detected and assessed on November 12, 2015. The area was later verified to be part of Brgy. Ingore, La Paz, Iloilo City.
After almost two months, the mangroves particularly the Avicennia species were observed by the BCWERC team to have recovered from the damages brought by the infestation. Mangrove trees were green and lush again. Some of them were still recovering especially those in the inner part of the mangrove area. No interventions were applied, they survived on their own.
According to Neil G. Gigare, Science Research Specialist of BCWERC Region 6, the mangroves survived because the pests are leaf feeders and considered as defoliators. They cause damage to the host plants during their larval stage. The moth which is the adult stage can no longer cause damage. Mr. Gigare added that some of the ‘tide watching mangrove moths’ especially the males died after maturing, eaten by predators, blown away by the wind and some hibernated. Others may infest other plants but with lesser damage because they are already few.
Severe infestation will happen again when the time and condition of the environment favor them while they are present on the host plant. It is during the dry season that environmental condition is most favorable for them creating greater possibility to the outbreak of pest infestation.
On the other hand, according to Mr. Gigare, severe infestations through defoliation have some positive result to the affected mangrove area. Sunlight penetration will increase which will favor growth of some species of plants and microorganisms in the mangrove area. It will also provide nutrients in the mangrove floor in the form of worm casting and dead insect pest. The presence of the insect pest in the mangroves could be enjoyed by some predators in the area. The Avicennia may have appeared dead but their leaves sprouted again, they grew and recovered after the infestation. The cooperation of the people in Lapaz for not cutting the infested mangroves also helped a lot in the survival of the mangroves. The best way to assist in the recovery is to protect and refrain from cutting the mangroves when similar pest occurrence happens again. Lynly Florence B. Palma, BCWERC