Some Aspects of the Biology and Ecology of Neurothemis Tullia (Drury) (Odonata:Libellulidae) in the Laboratory and Rainfed Rice Field in Peninsular Malaysia

The life cycle, life history, feeding biology and ecology of Neurothemis tullia (Drury) larvae and adults were studied from June 1993 through April 1995 in a rice field of Bandar Baru District in Kedah, Malaysia. An aquatic net was used to sample the lar.-ae in the field and the adult ecology was studied using visual counting and Mark-Release-Recapture (MRR) techniques. The results showed that the egg incubation period was eight days followed by forty four days of larval developmental period in the laboratory. Thus, the mean life cycle from egg to adult emergence was fifty two days. Growth of both head capsule and body length was faster from instar one to six and slowed gradually at higher instars. Larval development was asynchronous and a maximum of eight different instars was found at one sampling occasion. Four emergences were observed in the year of 1994. The onset of emergence occurred in March, May, July and October, 1994. The size of emerging populations varied according to the availability of water during larval growth and rice growing phases. Some of the larvae were able to survive in the rice field during short dry periods of less than four weeks. The abundance of the larvae was higher in 1994 compared to 1993. Generally more larvae were found during tiller, mature field and fallow phases of rice cultivation. No correlation was found between the abundance of the larvae and any of the water parameters i.e. temperature, pH, dissolved oxygen, conductivity, nitrate, phosphate, chlorophyll a and height of plants. The availability of water in the field however, determined the presence or absence of the larvae. Fifty one aquatic animal taxa coexisted with N. tullia of which the abundance of each of Orthetrum sabina (Drury), Anisoptera, Anopheles spp., Chironomidae, Corixidae and hemipteran Veliidae correlated positively with that of N. tullia. A hypothetical trophic relationship of N. tullia in the rice field is proposed. The highest estimated population of adults was 2400 individuals per 4.6 ha (-522 adults per ha). The male population peaked slightly earlier than the female population, possibly an indication of longer maturation period of the females. Adult populations were high when rice plants were growing in the field but decreased drastically after harvest. Prolonged drought further reduced the adult population density . A general pattern of adult abundance was obtained either by MRR technique or visual count method with the former generating more information than the latter. Survival rates of both male and female adults of N. tullia were >0.5 throughout the study. The mean life span durations were 42.4 and 36.5 days and the maximum life span durations were sixty five and fifty three days, respectively. The populations of N. tullia were unstable because the proportions of age classes varied through time. The adults were widely distributed within its home range of about 40 m. Their maximum distance travelled was approximately 130 m. The adults started feeding as early as 0730 hrs with two peaks of heaviest gut weights at 1030 hrs and 1730 hrs. At anytime of the day, the females guts were significantly heavier than the guts of the males (ANOVA, P=0.05) reflecting higher feeding activity and nutritive requirement by the females

Functional feeding group (FFG) of aquatic macroinvertebrate in middle reach of Kerian river basin of North Malaysia Peninsula

Investigations on the distribution and abundance of aquatic macroinvertebrates functional feeding group (FFG) in Bogak, Kerian and Serdang rivers of Kerian River Basin showed that there were 120 genera from 59 families of 13 orders of macroinvertebrates. Predator mainly Odonata, Hemiptera and Coleoptera was the most common group and found in high densities in Bogak River (modified river) and Kerian River (main river). The second dominant group in both rivers was collector-gatherer (Diptera and Ephemeroptera) followed by scraper (mollusks). A different pattern of FFG distribution was observed in Serdang River (tributary of Kerian River). The most abundant group was collector-gatherer, followed by predator and scraper. In general, predator abundance showed a significant positive correlation with their prey abundance (other feeding groups). Predator abundance especially in Bogak and Kerian rivers, was significantly influenced by parameters such PO4 3- , NO3 -N and Zn. In Serdang River, collector-gatherer abundance was affected by water temperature, velocity, TSS, turbidity, Mn and Cu content in the sediments. However, all water parameters weakly influenced the abundance of FFGs in all locations. High abundance of collector-gatherer in Serdang River was related to enriched water contributed by anthropogenic waste from surrounding residential areas. In general, dominant FFG in each river reflected the influence of different environmental conditions and availability of food sources in the area

Determination of suitable host plant for rearing of Coccus hesperidum (Homoptera: Coccidae)

Brown soft scale, Coccus hesperidum Linnaues (Homoptera: Coccidae) is an economically important pest on wide range of horticultural and agricultural crops. A study was carried out to determine the suitability of three host plants, black nightshade (Solanum nigrum), mandarin (Citrus reticulata) and cotton (Gossypium barbadense), for mass rearing of C. hesperidum under laboratory conditions of 25±2 °C, 65±5% RH and photoperiod of 14D:10L. C. hesperidum was able to develop and reproduce on all three host plants. However, according to developmental period, longevity and fecundity, mandarin was the best among the three host plants

Preliminary distribution of Ephemeroptera, Plecoptera and Trichoptera (EPT) in Kerian River Basin, Perak, Malaysia

A preliminary study on three aquatic insect orders, Ephemeroptera (mayfly), Plecoptera (stonefly) and Trichoptera (caddisJly) (EPT) was carried out in Kerian River Basin (KRB), at the border of Kedah-Perak states, in Peninsular Malaysia. Ephemeroptera comprising six families of 10 genera and 460 individuals was the most dominant order. Although both Plecoptera and Trichoptera was represented l7y similar number of families, stoneflies were found to be more abundant in the river basin. In order of abundance, stonefly Tetropina, mayJlies Caenis, and centroptilum, and caddisJly Macrostemum were the most common geneva. The diversity of the EPTfauna ranged 1.41 - 2.65 with significantly different distribution (ANOVA, F/534o = 1.68) at P= 0.05 and fairly unevenly distributed (Evennes Index Ranged 0.15-0.95). The EPT Richness i~dices were in low ranges in all river and the FBI scores categorised the water quality of river in this river basin as moderately polluted to excellent

Assessment of Suitability of Kerian River Tributaries Using Length-weight Relationship and Relative Condition Factor of Six Freshwater Fish Species

The length-weight relationship and condition factor of six freshwater fish species were conducted monthly at selected rivers of Kerian River Basin from May 2008 to May 2009. The fish species studied were Devario regina, Labiobarbus sp., Puntius binotatus, Rasbora sumatrana, Acantopsis choironrhycos and Cyclocheilichthys apogon.  The value of fish growth (b) shows that D. regina (b = 3.256), P. binotatus (b = 3.911), R. sumatrana (b = 3.642) and C. apogon (b = 3.623) had positive allometric growth, while Labiobarbus sp. (b = 2.898) and A. choironrhycos (b = 2.427) had negative allometric growth. The mean Kn varied from 1.003 ± 0.109 (A. choirorhynchos) to 1.873 ± 0.203 (R. sumatrana). Of all the fish species, only mean Kn of R. sumatrana showed significant difference among the sampling sites, at P < 0.05, suggesting the fish growth in the Kerian River basin was in a good condition. Keywords: Length-weight relationship, condition factor, freshwater, Kerian River Basin, Malaysi

Seasonal influence on structuring aquatic insects communities in upstream rivers Belum-Temengor Forest Complex

The plausible effect of seasonal change (wet and dry) on the structure of aquatic insect community was investigated at rivers in Belum-Temengor Forest Complex (BTFC), Perak, Malaysia. The amount of rainfall received was considered as seasonal changes in the tropical regions. The rivers were visited twice in dry and wet seasons to sample aquatic insects using rectangular aquatic nets. Their abundance and richness varied significantly between both dry and wet seasons (P = 0.000; Mann-Whitney U test). More aquatic insect was collected in dry seasons (17,633 individuals) compared to wet seasons (6,542 individuals). The aquatic insect abundance decreased tremendously during the wet seasons (45% reduction) and diversity showed fewer species richness in the wet season (98 genera) compared to the dry season (114 genera). The most affected taxa caused by the heavy water flow were Ceratopsyche sp. (family Hydropschidae and subfamily Limoniinae which huge reduction in density occurred during the wet season. Water temperature, BOD3, DO and COD were significantly different between seasons (Kruskal Wallis test, P < 0.05). The presence of phosphorus and ammonia-nitrogen in water during dry season had major influence on the aquatic insect composition while rainfall was the main factor that regulated the insect communities in wet seasons

Effect of environmrntal disturbances on odonata assemblages along a tropical polluted river

Odonata larvae have been intensively used as bioindicators for freshwater pollution as their community structure closely follow changes in the environment and habitat settings. In this study, 28 taxa of Odonata larvae were collected from three stations (upper, middle and lower) of a polluted river in Malaysia. The upper river basin receives effluents from an oil palm plantation. However, the middle station is presumably contaminated with anthropogenic wastes. The lower station is found to receive polluted discharges from aquaculture outlet. Several environmental parameters of water and sediment were continuously measured during the study. The water parameters showed no significant differences amongst the three stations. The species richness of Odonata was 22, 24 and 20 in the upper, middle and lower stations, respectively. The abundance of Odonata was significantly different among the studied sites. The tolerant damselfly, Pseudagrion sp. (41.22%), and facultative dragonflies, Onychothemis sp. (17.12%), were the most dominant taxa along the river stations. Onychothemis sp. and Paragomphus capricornis were equally important at the upper station [Important Species Index (ISI) 25.3 and 24.2%, respectively]. Pseudagrion sp. only scored an ISI value of 9.7%. Pseudagrion sp., P. capricornis and Onychothemis sp. were dominant in the middle station (ISI: 41.2%, 25.9% and 10.9% respectively), and Pseudagrion sp., Onychothemis sp. and Prodasineura sp. dominated the areas with dense growth of submerged aquatic weeds Hydrilla sp. in the lower station (ISI: 47.9, 24.5 and 13.8%, respectively). On the basis of the variations in larval abundance and ISI values, microhabitats differences partly in response to different types of pollutions entering the water structured the Odonata communities in this river basin

Terrestrial insects as the main food for freshwater fish in Sungai Kerian tributaries: an implication on habitat conservation

The importance of terrestrial insects as food items for freshwater fish was studied by examining stomach contents of Devario regina (Fowler 1934) and its population parameters at canopied areas of selected tributaries of Sungai Kerian, in the northern state of Peninsular Malaysia. Ninety six percent (121 out of 126) of the fish stomachs examined contained food materials in the stomachs and the values of percentage of occurrence (%F), percentage numerical (%N) and percentage points (%P) indicated that collected fish ate similar food items in all rivers. Among the food categories, scavenging terrestrial ants (Formicidae) were the most dominant food item, hence the main diet for this species. The Index of Relative Importance (IRI) scores of food items indicated that ants were higher than other food items. This surface water feeder experienced a positive allometric growth (W = aLb) with a b (rate of growth) value of 3.256. Its asymptotic length, growth constant and growth performance index represented this species with a short life-span (L∞ = 10.90 cm, K = 1.20 year-1, φ’ = 2.15, tmax = 3 year, respectively) and had higher natural mortality (M = 2.40 year-1) than fishing mortality (F = 0.35 year-1) while the fish stock was underexploited (E = 0.13). The finding of this study indicated the importance of terrestrial ants as a food source that support excellent growth of D. regina and the need to conserve riparian trees along river banks to provide allocthonous materials and habitats for the ants

Scientific notes on coptosoma variegatum herrich-schaeffer, 1838 (Hemiptera: Plataspidae): a potential pest of mango flower in Malaysia

The incidence of infestation by a black stink bug Coptosoma variegatum (Hemiptera: Plataspidae) on mango Mangifera indica L. (Anacardiaceae) tree was scientifically reported for the first time in Malaysia. This insect is commonly known as home invader and legume pest. Abundance of this insect was monitored on mango panicles by 15 minutes hourly collection from 0800 h until 1500 h at 4-day interval from the beginning of flowering until all flowers dried up (12-28 February 2013 and 28 January 2014 – 7 March 2014). Five hundred twenty-six individuals collected during the study period with drastic increase observed in second season. However, their infestation on mango flowers was not fully evident therefore was suggested as a potential pest for mango flower in Malaysia solely due to their appearance on mango panicles. Nevertheless, co-occurrence of this sap-sucking insect with other secondary pests may pose a serious economic implication on the productivity of the crop. Thus, more research regarding this insect biology is required so that control requirement can be identified to maximize mango production in Malaysia

Population ecology of whitefly, Bemisia tabaci, (Homoptera: Aleyrodidae) on brinjal

Whitefly, Bemisia tabaci (Gennadius), a common insect feeding on plants, belongs to the family Aleyrodidae of the order Homoptera. The quantity of food source especially brinjal, is one of the major factors that has attracted whitefly in the area. In fact, the flight ability of whitefly enables them to search for food quickly. Thus could encourage whitefly to reproduce in great numbers and subsequently cause severe infestation in the fields. Many farmers are not interested to grow brinjal after they have gone through some bad experience due to some whitefly infestations, which have resulted in a total crop loss of brinjal fruits. At present, information on the population dynamics of whiteflies locally on brinjal is still lacking. Henceforth, these studies are indeed appropriate to generate a comprehensive understanding on the insect population, which could support an effective pest management programme and crop improvement strategy. The study was conducted at the Field Laboratory of the Faculty of Applied Science, Universiti Teknologi MARA, Shah Alam. The study on the population of whitefly larvae on brinjal plants covered all the plant strata except for the upper stratum. The populations of whitefly were aggregated (Taylor’s Power Law Calculate) in first and second cropping of brinjal plants. It may be concluded that the total number of whitefly larvae were found to be most abundant in the middle stratum of the brinjal plants