Academia Journal of Biology

The mudskipper Boleophthalmus boddarti is an amphibious fish widely distributed in the mudflat regions in Asia, but its reproductive biology was poorly stydied. This study was conducted in the Tran De, Soc Trang, Vietnam, from March 2013 to February 2014, to investigate reproductive parameters of B. boddarti. Data analysis based on a total of 360 collected fish (188 females and 172 males) suggest that the sex ratio of this mudskipper was not significantly different between dry and wet seasons. This fish was a multiple reproducer and spawned in the wet season with a peak spawning in three main months of this season (August to October) as difference stages of oocytes were observed in the ovaries. The male B. boddarti released sperms during the reproductive season since different type of spermatogonia were found in stage V testis sections. This fish reached 11.52 cm total length at first sex maturation and was high fecundity (9,800-33,800 eggs), indicating a possible adaptation of this species to the monsoonal climate. The understanding of the reproductive biology of B. boddarti provides useful knowledge of its reproductive adaptation to the mudflat toward sustainable management in the study region.

This study provides information on the growth and body condition variation of the giant mudskipper Periophthalmodon schlosseri between gender and fish size during dry and wet seasons. A total of 367 fish specimens was collected along mudflat and mangrove forest in Tran De from May 2014 to April 2015. The sex ratio of this fish was nearly 1:1. This species showed isometric growth as its slope value was close to the standard threshold (e.g., 3), and its length-weight relationship was similar in both dry and wet seasons. Although the condition factor of this mudskipper varied with seasonal change and fish size, it was similar in males and females and close to well-being value (e.g., 1). These results indicated that this fish lives well and can become a potential fish for aquaculture in this area, and provides useful information for our knowledge to other gobiid fishes. 

The mudskipper Boleophthalmus boddarti (Pallas, 1770) is an important commercial fish, but information on its dietary composition has been limited. This study was carried out from March 2013 to February 2014, in Tran De, Soc Trang, Mekong Delta, Vietnam to understand its food, foraging intensity and fullness index. A total of 120 fish specimens including 63 females (8-15 cm in TL) and 57 males (9.5-15.1 cm in  TL) were collected and analysed. The results showed that the sex ratio of B. boddarti was close to 1:1 and this mudskipper would be a herbivorous fish due to high relative gut length value (RGL>1) based on 120 gastrointestinal tract length analysis. Among them, 75 fish stomachs were used for food item determination. The B. boddarti fed mainly on Bacillariophyta (82.97%), and detritus was also composed in its stomach contents (13.26%). The mudskipper showed high in foraging intensity due to high fullness index value. The variation of food composition of this fish depended on season, but not in gender and fish size. The results provided useful information on diet composition of B. boddarti and contributed to our knowledge for other gobies living in the monsoonal regions. 

Braconidae (Hymenoptera) is one of two most diverse families of Hymenoptera and both belong to the superfamily Ichneumonoidea, most braconid wasps are known as parasitoids of other insects damaging agricultural crops, many members of the parasitic braconid wasps are the important agents for biological control of insect pests. This paper presented the list of 210 braconid wasps of the family Braconidae from Vietnam with the information of the museums where the types are deposited, the published papers of the first record of braconid species in Vietnam, hosts and distribution of braconid species. Sixty two species recorded for the first time from Vietnam, which is 12.6% of the 492 braconid species belonging to 24 subfamilies now known from Vietnam. Additionally, there are 18 species listed with information about their hosts, being agricultural pests controlled to some degree by these parasitoids.

Boleophthalmus boddarti (Pallas, 1770) is one of mudskippers (Gobiidae), and a potential commercial fish in Mekong Delta, Vietnam. The study on the goby B. boddarti was investigated in Tran De district, Soc Trang province, Mekong Delta, Vietnam, to establish some basic population biology parameters. A total of 117 individuals were caught in mudflats of Tran De beach by deep net to determine length-weight relationships of this species. After determining sex by external features, total length (TL in cm), and body weight (W in g) of this goby were measured. This study ran for six months, from January 2013 to June 2013. The mean lengths of female significantly differed from value of male, whereas the average body weights of male and female were quite similar. The proportion of male and female groups were not substantially different. The length-weight relationships of total fish, male and female were highly correlated with high regression values which were 0.813, 0.866 and 0.767, respectively. The slope values of this mudskipper was 3.21±0.32 which was not significant higher cubic value (three), suggesting the growth relationship of this species was isometric growth and could be a potential fish for future aquaculture.

The taxonomy of the species of Cupressaceae indigenous to Vietnam is reviewed. Cupressus tonkinensis Silba is considered the correct name for the Cupressus in Langson province, not Cupressus torulosa. The genus Xanthocyparis is reduced to a subgenus of Cupressus and the new combination Cupressus vietnamensis (Farjon & Hiep) Rushforth made. The genus Fokienia is not considered separable from Chamaecyparis and the combination Chamaecyparis hodginsii (Dunn) Rushforth is made. The conifers associated with Cupressus vietnamensis and their conservation are discussed.

The paper listed 50 species of 18 genera belonging to the tribe Cerambycini from Vietnam, of the total 50 species there are five species  newly recorded for the Vietnam’s fauna, viz. Aeolesthes (Pseudaeolesthes) pericalles Gressitt & Rondon, 1970 and one species of the genus Aeolesthes s.s. are Aeolesthes sinensis Gahan, 1890; Derolus ornatus Gressitt & Rondon, 1970; Dymasius maculatus Gressitt & Rondon, 1970; Massicus raddei (Blessig, 1872). Diagnosis of all genera are presented with notes on distribution. An illustrated key to 18 genera of the tribe Cerambycini is also provided.

Three new free-living nematode species of the order Monhysterida from Me Kong river estuaries of Vietnam are described. Daptonema brevisetosum sp. nov. resembles to Daptonema setosum (Bütschli, 1874), but differs from it by the relatively shorter outer labial setae, shorter spicules and shorter cervical and somatic setae. Subsphaerolaimus major sp. nov. similar to Subsphaerolaimus lamasus (Gerlach, 1956), Subsphaerolaimus gerlachi (Wieser, 1959) and Subsphaerolaimus litoralis Lorenzen, 1978, but differs from them by the longer body, longer spicules and presence of dorso-caudal apophysis of gubernaculum. Daptonema hirtum (Gerlach, 1957) is restored from synonymy of Daptonema setosum (Bütschli, 1874) and it is raised to range of valid species.

Most species of the longhorned beetles are known to damage living trees and attack dead trees or fallen logs and are of economic importance because their wood­boring larvae are destructive to plants and freshly cut logs. The paper presented a checlist of publising species of Vietnam longhorn beetle fauna of the subfamily Cerambycinae with local and world distribution provided. Of the total of 259 cerambycid species belonging to 88 genera and 18 tribes, seven diverse tribes are Clytini (74 species), Callichromini (41 species), Cerambycini (35 species), Molorchini (19 species), Callidiopini (18 species), Methiini (13 species) and Cleomenini (11 species).

Microalga Haematococcus pluvialis Flotow is one of the natural sources of astaxanthin, a pigment widely used in aquaculture, food, pharmaceutical and nutraceutical industries. In the present study, we investigated the effect of high NaCl concentrations on growth and astaxanthin accumulation in the microalga. Growth was observed under different salt concentrations (0.8%, 1.5% and 2.5% NaCl) according to two - phase culture mode. The obtained results have indicated that the high NaCl concentrations caused an increase in carotenoid content per cell and a decrease in the algal growth. The best carotenogenic condition by addition of salt was obtained at 2.5% NaCl under high temperature. Astaxanthin content per cell increased 4.8 folds in comparison to the initial value, from 10 pg.cell-1 to 48 pg.cell-1 after 15 days of salt stress. We observed that the accumulation of total lipid content was correlated with an increasing in astaxanthin content. The total lipid content of control was 15 ± 0,35% of dry cell weight whereas that of cell exposed to salt stress was 19% ± 1,3% and 26 ± 0.12% at 1.5% and 2.5% NaCl concentrations, respectively. This study will be an initial basis for the two phase culture process to obtain astaxanthin rich Haematococcus pluvialis biomass.