The Philippine Scientist

Aspects of the population biology of the buccaneer anchovy Enrasicholina punctifer (Fowler 1938) in Southern Sibuyan Sea, Philippines

Drusila Esther E. Bayate, Joshua M. Regalado, May R. Guanco, Sheryll V. Mesa — Wed, 13 Feb 2019 00:00:00 +0800

The buccaneer anchovy Encrasicholina punctifer is one of many commercially important fishes in the Philippines. Fish catch of bag net boats based in Tangalan, Aklan which operate in Sibuyan Sea were monitored from January to December 2008. Monthly E. punctifer length-frequency data were used to estimate growth, mortality, and recruitment using FiSAT II Software. Growth parameters asymptotic length (L_∞) and growth constant (K) of the von Bertalanffy growth function were estimated to be 11.96 cm and 1.1 y^–1, respectively. Total mortality (Z) was estimated to be 5.75 y^–1 while values for fishing mortality (F) and natural mortality (M) were 3.29 and 2.46, respectively. Annual recruitment pattern consisted of one major and one minor pulse, similar to other tropical fish stocks. Exploitation rate (E) was found to be 0.57, which is slightly above the desired value of 0.5. Results obtained in this study provide the first estimates of demographic parameters for the E. punctifer stock in Sibuyan Sea.

New Records of Philippine True Bugs (Hemiptera: Heteroptera) with Coastal and Marine Habitat Associations and a Checklist of the Philippine Species

Clister C. Pangantihon, Herbert Zettel, Hendrik Freitag — Wed, 13 Feb 2019 00:00:00 +0800

We present new records of Gerromorpha and Leptopodomorpha (Insecta: Hemiptera: Heteroptera) from the Philippines (mainly from central Visayan islands and Mindoro) and comment on their habitats and endemism rates. The survey includes previously unidentified museum specimens and recent field collections.
Photos of several taxa and their habitats are provided and a checklist of Philippine coastal and marine Heteroptera is presented with comments on their distribution.

Some Pediastrum species (Chlorophyceae) from Laguna de Bay (Philippines) and its vicinities

Milagrosa R. Martinez-Goss, Eldrin DLR. Arguelles, June Owen O. Nacorda — Wed, 13 Feb 2019 00:00:00 +0800

Seven species and varieties of microscopic, colonial (coenobic) green algae from the genus Pediastrum Meyen, sensu lato, were identified, described, documented, and their habitats were characterized. They were collected from Laguna de Bay and nearby freshwater habitats. This paper also presents the current list of species and varieties of Pediastrum for the Philippines, of which there are 13 taxa. Included in the list are two taxa that are reported as new to the country, i.e., Pediastrum simplex var. echinulatum and P. biwae var. ovatum.

The 2013 fish kill event in Ilog River-Estuary, Negros Occidental, Philippines

Thu, 25 Apr 2019 00:00:00 +0800

A fish kill (fin fishes and crustaceans) event was documented on April 22–26, 2013 in Ilog River-Estuary, Negros Occidental, in central Philippines. This event was characterized by reduced dissolved oxygen (hypoxia) which ranged from 0.6–3.86 mg O₂/L (mean 1.98 ± 0.49 s.e.) during the first day of the event. Several factors leading to the occurrence of the fish kill are discussed. Small-scale trawling, other fishing gears, and related activities were monitored during the months of April, May, September, October, December 2013 and January 2014 to further determine the possible impact of the fish kill event to the local fishery.

First report of Steinernema longicaudum and its bacterial symbionts, Xenorhabdus species, in pummelo orchards of Davao region, Philippines

Leslie Ubaub, Patricia Stock — Thu, 25 Apr 2019 01:22:22 +0800

Davao region is the largest pummelo-producing area in the Philippines. Like other tropical fruits, pummelo is infested with several insect pests which consequently lead to the application of synthetic chemicals as deterrent. One potential alternative control measure is the use of soil-dwelling, entomopathogenic nematodes (EPNs), each with its own suite of preferred host, which can be used to control a wide range of insect pests. A survey and soil samples were collected to isolate and identify EPNs in ten pummelo orchards in the Davao region. EPNs were extracted from soil samples using the insect-baiting technique, and were found in only two of the ten sampling areas. EPN isolates were subjected to molecular identification using the 28S ribosomal DNA (rDNA) while its bacterial symbionts were identified using 16S rDNA genes. Both EPN isolates were identified as Steinernema longicaudum. This is the first report of S. longicaudum isolate in the Philippines which can be used as biological control agent against insect pests of pummelo such as citrus rind borer and flower thrips.