Life History of Thalerosphyrus (Ephemeroptera: Heptageniidae) in Tropical Rivers with Reference to the Varying Altitude.

The life history and the influence of environmental parameters on Thalerosphyrus were investigated in two first-order rivers-the Batu Hampar River and the Teroi River of Gunung Jerai, Kedah-in northern peninsular Malaysia. Based on nymphal body length, Thalerosphyrus was found to be trivoltine in both rivers, regardless of the altitudinal difference, but its population abundance was four times higher in the Teroi River, presumably related to its better survival in the lower water temperature. At least nine instars of Thalerosphyrus were detected in the field-collected nymphs. Its life cycle was completed within 2.5-3.0 months, with overlapping cohorts and continual emergence of up to 3 months. The main driving factors of the high abundance of Thalerosphyrus were the water temperature and habitat quality.

Efficiency of Different Sampling Tools for Aquatic Macroinvertebrate Collections in Malaysian Streams.

This study analyses the sampling performance of three benthic sampling tools commonly used to collect freshwater macroinvertebrates. Efficiency of qualitative D-frame and square aquatic nets were compared to a quantitative Surber sampler in tropical Malaysian streams. The abundance and diversity of macroinvertebrates collected using each tool evaluated along with their relative variations (RVs). Each tool was used to sample macroinvertebrates from three streams draining different areas: a vegetable farm, a tea plantation and a forest reserve. High macroinvertebrate diversities were recorded using the square net and Surber sampler at the forested stream site; however, very low species abundance was recorded by the Surber sampler. Relatively large variations in the Surber sampler collections (RVs of 36% and 28%) were observed for the vegetable farm and tea plantation streams, respectively. Of the three sampling methods, the square net was the most efficient, collecting a greater diversity of macroinvertebrate taxa and a greater number of specimens (i.e., abundance) overall, particularly from the vegetable farm and the tea plantation streams (RV<25%). Fewer square net sample passes (<8 samples) were sufficient to perform a biological assessment of water quality, but each sample required a slightly longer processing time (±20 min) compared with those gathered via the other samplers. In conclusion, all three apparatuses were suitable for macroinvertebrate collection in Malaysian streams and gathered assemblages that resulted in the determination of similar biological water quality classes using the Family Biotic Index (FBI) and the Biological Monitoring Working Party (BMWP). However, despite a slightly longer processing time, the square net was more efficient (lowest RV) at collecting samples and more suitable for the collection of macroinvertebrates from deep, fast flowing, wadeable streams with coarse substrates.

Efficacy of Insecticide and Bioinsecticide Ground Sprays to Control Metisa plana Walker (Lepidoptera: Psychidae) in Oil Palm Plantations, Malaysia.

The effectiveness of the synthetic insecticides trichlorfon, lambda-cyhalothrin, cypermethrin emulsion concentrated (EC) and cypermethrin emulsion water based (EW) and a bio-insecticide, Bacillus thuringiensis subsp. kurstaki (Btk), was evaluated at 3, 7, 14 and 30 days after treatment (DAT) for the control of Metisa plana larvae in an oil palm (Elaeis guineensis) plantation in Malaysia. Although all synthetic insecticides effectively reduced the larval population of M. plana, trichlorfon, lambda-cyhalothrin and cypermethrin EC were the fastest-acting. The larval population dropped below the economic threshold level (ETL) 30 days after a single application of the synthetic insecticides. Application of Btk, however, gave poor results, with the larval population remaining above the ETL post treatment. In terms of operational productivity, ground spraying using power spray equipment was time-consuming and resulted in poor coverage. Power spraying may not be appropriate for controlling M. plana infestations in large fields. Using a power sprayer, one man could cover 2-3 ha per day. Hence, power spraying is recommended during outbreaks of infestation in areas smaller than 50 ha.

An update on the incidence of dengue gaining strength in Saudi Arabia and current control approaches for its vector mosquito.

BACKGROUND: The cases of dengue reported earlier in the late 1990s from the Kingdom of Saudi Arabia (KSA) occurred in the cities of Jeddah and Makkah. Although the kingdom has ample financial resources to establish effective control measures for the dengue vector, numerous cases of dengue occur and fluctuate in numbers from year to year. This necessitates a serious review of the current vector control strategies being practiced in order to identify the existing shortcomings. This short report provides an update on epidemiology of dengue in KSA (specifically in cities of Jeddah and Makkah) with a critical look at the current vector control strategies. FINDINGS: In 2013, 4411 cases of dengue were reported, with 8 cases of mortality. This number of dengue incidence was four times higher compared to 2012. In 2013, the highest number of 1272 dengue cases was reported in May, while the lowest number (37) of cases was reported in September. CONCLUSIONS: It is evident that the control strategies of the dengue vector presently employed are inadequate. There seems to be serious deficiencies in following proper scientific procedures during field application(s) of control materials against the vector as is evident by the increases in the number of dengue cases as well as frequent outbreaks of the vector mosquito populations. In this review, some specific suggestions are made to draw attention to the relevant KSA authorities of the possible reasons behind unsuccessful control results and as to how to improve the strategy of dengue vector control in the kingdom.

Indirect effects of cigarette butt waste on the dengue vector Aedes aegypti (Diptera: Culicidae).

Despite major insecticide-based vector control programs, dengue continues to be a major threat to public health in urban areas. The reasons for this failure include the emergence of insecticide resistance and the narrowing of the spectrum of efficient products. Cigarette butts (CBs), the most commonly discarded piece of waste, also represent a major health hazard to human and animal life. CBs are impregnated with thousands of chemical compounds, many of which are highly toxic and none of which has history of resistance in mosquitoes. This study was performed to examine whether exposure to CB alters various biological parameters of parents and their progeny. We examined whether the mosquito changes its ovipositional behaviors, egg hatching, reproductive capacity, longevity and fecundity in response to CB exposure at three different concentrations. Females tended to prefer microcosms containing CBs for egg deposition than those with water only. There were equivalent rates of eclosion success among larvae from eggs that matured in CB and water environments. We also observed decreased life span among adults that survived CB exposure. Extracts of CB waste have detrimental effects on the fecundity and longevity of its offspring, while being attractive to its gravid females. These results altogether indicate that CB waste indirectly affect key adult life traits of Aedes aegypti and could conceivably be developed as a novel dengue vector control strategy, referring to previously documented direct toxicity on the larval stage. But this will require further research on CB waste effects on non-target organisms including humans.

The Influence of Heavy Metals and Water Parameters on the Composition and Abundance of Water Bugs (Insecta: Hemiptera) in the Kerian River Basin, Perak, Malaysia.

The hemipteran (Insecta) diversity in the upper part of the Kerian River Basin was low with only 8 families and 16 genera recorded at 4 study sites from 3 rivers. Water bug composition varied among sampling sites (Kruskal-Wallis χ (2) = 0.00, p<0.05) but was not affected by wet-dry seasons (Z = 0.00, p>0.05). All recorded water parameters were weakly associated with generic abundance but the biochemical oxygen demand (BOD), chemical oxygen demand (COD), Water Quality Index (WQI) and heavy metals (zinc and manganese) showed relatively strong positive or negative relations with hemipteran diversity and richness (H' and R2). Within the ranges of measured water parameters, the WQI was negatively associated with hemipteran diversity and richness, implying the tolerance of the water bugs to the level of pollution encountered in the river basin. Based on its highest abundance and occurrence (ISI), Rhagovelia was the most important genus and along with Rheumatogonus and Paraplea, these genera were common at all study sites. In conclusion, habitat availability and suitability together with some environmental parameters influenced the abundance and composition of hemipterans in this river basin.

Turning cigarette butt waste into an alternative control tool against an insecticide-resistant mosquito vector.

Annually, 4.5 trillion cigarette butts (CBs) are flicked into our environment. Evidence exists that CB waste is deadly to aquatic life, but their lethality to the aquatic life of the main dengue vector is unknown. CBs are full of toxicants that occur naturally, during planting and manufacturing, which may act as larvicidal agents. We assessed Aedes aegypti vulnerability to Marlboro butts during its development. Overall, CBs showed insecticidal activities against larvae. At early phases of development, mortality rates were much higher in two CBs solution (2CBSol) and 3CBSol microcosms (MICRs). Larval survival gradually decreased with development in 1CBSol-MICRs. However, in great presence of CBs, mortality was high even for the late developmental stages. These results suggest that A. aegypti larvae are vulnerable to CB presence in their habitats, but this effect was seen most during the early developmental phases and in the presence of increased amounts of cigarette remnants. CB filters are being used as raw material in many sectors, i.e., brick, art, fashion, plastic industries, as a practical solution to the pollution problem, the observed butt waste toxicity to mosquito larvae open new avenues for the identification of novel insecticide products.

Colonized Aedes albopictus and its sexual performance in the wild: implications for SIT technology and containment.

BACKGROUND: Mating is a physiological process of crucial importance underlying the size and maintenance of mosquito populations. In sterile and incompatible insect technologies (SIT and IIT), mating is essential for mass production, persistence, and success of released individuals, and is a central parameter for judging the effectiveness of SIT/IIT programs. Some mosquitoes have an enormous reproductive potential for both themselves and pathogens and mating may contribute to persistence of infection in nature. As Aedes albopictus can transmit flaviviruses both sexually and horizontally, and as infected insects are usually derived from laboratory colonies, we investigated the implications of mating between a long-term laboratory colony of Ae. albopictus and wild populations. METHODS: Through a series of mating experiments, we examined the reproductive outcomes of sexual cross-affinity between laboratory-raised and wild adults of Ae. albopictus. RESULTS: The results indicated appreciable mating compatibility between laboratory-reared and wild adults, and equivalent levels of egg production among reciprocal crosses. We also observed comparable larval eclosion in lab females mated with wild males, and increased adult longevity in female offspring from wild females|×|laboratory males crosses. CONCLUSIONS: Taken together, these data suggest that Ae. albopictus can preserve its reproductive fitness over a long period of time in the laboratory environment and has valuable attributes for SIT application. These observations together with the ability to successfully inseminate heterospecific females indicate the potential of Ae. albopictus to act as an ecological barrier if non-sterilized males are massively released in areas occupied by Aedes aegypti. The observed substantial reproductive fitness combined with the capability to reproduce both, itself and viruses illustrates the potential of Ae. albopictus to pose a serious threat if infected and released accidentally.

Genotoxicity of heavy metals to the larvae of Chironomus kiiensis Tokunaga after short-term exposure.

The genotoxic effects of increasing concentrations (below lethal concentration [LC50]) of cadmium ([Cd] 0.1, 1 and 10 mg/L), copper ([Cu] 0.2, 2 and 20 mg/L) and zinc ([Zn] 0.5, 5 and 50 mg/L) on Chironomus kiiensis were evaluated using alkaline comet assay after exposure for 24 h. Both the tail moment and the olive tail moment showed significant differences between the control and different concentrations of Cd, Cu and Zn (Kruskal-Wallis, p < 0.05). The highest concentration of Cd was associated with higher DNA damage to C. kiiensis larvae compared with Cu and Zn. The potential genotoxicity of these metals to C. kiiensis was Cd > Cu > Zn.

The species composition of thrips (insecta: thysanoptera) inhabiting mango orchards in pulau pinang, malaysia.

A field study was conducted at two localities on Pulau Pinang, Malaysia, during two consecutive mango flowering seasons in 2009 to identify variations in the species composition of thrips infesting treated and untreated mango (Mangifera indica L.) orchards. The CO2 immobilisation technique and the cutting method were used to recover different thrips species from mango panicles and weed host plants, respectively. The mango panicles and various weed species within the treated orchard were found to harbour four thrips species from the family Thripidae. These species were identified as Thrips hawaiiensis (Morgan), Scirtothrips dorsalis (Hood), Frankliniella schultzei (Trybom) and Megalurothrips usitatus (Bagnall). The weed species Mimosa pudica, Cleome rutidosperma, Echinochloa colonum, Borreria laevicaulis, Veronia cinerea and Asystasia coromandeliana served as additional hosts to these thrips. Six thrips species were found in the untreated orchard. These species included Thrips palmi (Karny), Haplothrips sp. (Amyot and Serville) and the four thrips species found in the treated orchard. A brief description of the larvae for each genus is provided.

Redescription of Chironomus javanus and Chironomus kiiensis (Diptera: Chironomidae) Larvae and Adults Collected from a Rice Field in Pulau Pinang, Malaysia.

Chironomus javanus (Kieffer) and Chironomus kiiensis Tokunaga were redescribed from materials collected from a rice field in Pulau Pinang, Malaysia. The larvae can only be distinguished after careful preparation and examination using a compound microscope, but the pupae were not useful to differentiate C. javanus from C. kiiensis. The adult specimens showed clear body and wing characteristics for rapid and accurate identification.

Discarded cigarette butts attract females and kill the progeny of Aedes albopictus.

Discarded cigarette butts (DCB) waste occurs worldwide, pollutes landscapes, is unsightly, and results in added debris removal costs. There is, therefore, a great deal of current interest in making use of DCBs in beneficial ways. Despite evidence that DCBs are harmful to water fleas (Daphnia magna), which breed in aquatic environments as do mosquito larvae, their impact on dengue vectors is unknown. We examined whether Aedes albopictus alters its ovipositional responses, larval eclosion, and development in response to presence of DCBs in its habitats. We found oviposition activity in DCB-treated water similar to that of control water and that ovipositional activity in DCB solutions steadily increased over time as those solutions aged to 10 days. Larval eclosion was initially suppressed on day 1 in DCB solution, but increased thereafter to levels similar to control larval eclosion rates. The DCB-water solutions produced significantly higher mortality in both 1st and 2nd instars over control larvae for several days after initial exposure. Mortality rates decreased sharply 3 to 5 days postexposure as DCBs continued to decompose. We found increased survival rates during late development, but daily input of fresh DCBs prevented most young larvae from completing development. Taken together, these observations suggest that decomposing did not deter gravid Ae. albopictus females from ovipositing in treated containers and that DCB solutions had larvicidal effects on early instars. Our results are discussed in the context of DCB use to control container-breeding Ae. albopictus, a competent dengue vector in Asia and other parts of the world.

Evaluation of yellow sticky traps for monitoring the population of thrips (Thysanoptera) in a mango orchard.

Populations of several thrips species were estimated using yellow sticky traps in an orchard planted with mango, Mangifera indica L. during the dry and wet seasons beginning in late 2008-2009 on Penang Island, Malaysia. To determine the efficacy of using sticky traps to monitor thrips populations, we compared weekly population estimates on yellow sticky traps with thrips population sizes that were determined (using a CO(2) method) directly from mango panicles. Dispersal distance and direction of thrips movement out of the orchard also were studied using yellow sticky traps placed at three distances from the edge of the orchard in four cardinal directions facing into the orchard. The number of thrips associated with the mango panicles was found to be correlated with the number of thrips collected using the sticky trap method. The number of thrips captured by the traps decreased with increasing distance from the mango orchard in all directions. Density of thrips leaving the orchard was related to the surrounding vegetation. Our results demonstrate that sticky traps have the potential to satisfactorily estimate thrips populations in mango orchards and thus they can be effectively employed as a useful tactic for sampling thrips.

Growth of Chrysomya megacephala (Fabricius) maggots in a morgue cooler.

In estimating the postmortem interval (PMI) using maggots obtained during autopsy, the forensic entomologist makes decisions regarding the effects of low-temperature storage of the body on the insects. In this case report, a corpse was found in an abandoned house in the residential area of Bukit Mertajam, Penang, Malaysia. The maggots were found to be alive inside the mouth of the deceased although the corpse had been in the morgue cooler for 12 days. The maggots were reared and identified as Chrysomya megacephala (Fabricius). The emerged adult flies were kept as a stock colony, and the duration of development under the indoor fluctuating temperature regime was studied. The total duration of developmental process of this species was 9.5 ± 0.5 days, and the PMI estimated was 3.2 ± 0.6 days. This case report demonstrates the survival of Ch. megacephala maggots for 12 days and their growth inside the morgue cooler.

Diurnal activity of four species of thrips (Thysanoptera: Thripidae) and efficiencies of three nondestructive sampling techniques for thrips in mango inflorescences.

Thrips cause considerable economic loss to mango, Mangifera indica L., in Penang, Malaysia. Three nondestructive sampling techniques--shaking mango panicles over a moist plastic tray, washing the panicles with ethanol, and immobilization of thrips by using CO2--were evaluated for their precision to determine the most effective technique to capture mango flower thrips (Thysanoptera: Thripidae) in an orchard located at Balik Pulau, Penang, Malaysia, during two flowering seasons from December 2008 to February 2009 and from August to September 2009. The efficiency of each of the three sampling techniques was compared with absolute population counts on whole panicles as a reference. Diurnal flight activity of thrips species was assessed using yellow sticky traps. All three sampling methods and sticky traps were used at two hourly intervals from 0800 to 1800 hours to get insight into diurnal periodicity of thrips abundance in the orchard. Based on pooled data for the two seasons, the CO2 method was the most efficient procedure extracting 80.7% adults and 74.5% larvae. The CO2 method had the lowest relative variation and was the most accurate procedure compared with the absolute method as shown by regression analysis. All collection techniques showed that the numbers of all thrips species in mango panicles increased after 0800 hours, reaching a peak between 1200 and 1400 hours. Adults thrips captured on the sticky traps were the most abundant between 0800-1000 and 1400-1600 hours. According to results of this study, the CO2 method is recommended for sampling of thrips in the field. It is a nondestructive sampling procedure that neither damages flowers nor diminishes fruit production. Management of thrips populations in mango orchards with insecticides would be more effectively carried out during their peak population abundance on the flower panicles at midday to 1400 hours.

Distribution of chironomidae (Insecta: Diptera) in polluted rivers of the Juru River Basin, Penang, Malaysia.

The influence of physical and chemical parameters on the abundance and diversity of chironomids was studied in six rivers with moderate to highly polluted water in the Juru River Basin. The rivers: Ceruk Tok Kun (CTKR) as reference site, and polluted rivers of Pasir (PR), Juru (JR), Permatang Rawa (PRR), Ara (AR) and Kilang Ubi (KUR) were sampled over a period of five months (November 2007-March 2008). Nine chirnomid species: Chironimus kiiensis, C. javanus, Polypedilum trigonus, Microchironomus sp., Dicrotendipes sp., Tanytarsus formosanus, Clinotanypus sp., Tanypus punctipennis and Fittkauimyia sp. were identified. Assessment of their relationships with several environmental parameters was performed using the canonical correspondence analysis (CCA). Tanytarsus formosanus was the most dominant in the relatively clean CTKR and moderately polluted JR with mean densities of 19.66 and 25.32 m(-2), respectively while C. kiiensis was abundant in more polluted rivers. Tanytarsus formosanus, Dicrotendipes sp. and Microchironomus sp. were grouped under moderate to high water temperature, total organic matter (TOM), total suspended solids (TSS), velocity, pH, phosphates and sulphates. However, Tanypus punctipennis, Fittkauimyia sp., and Clinotanypus sp. were associated with high contents of river sediment such as TOM, Zn and Mn and water ammonium-N and nitrate-N and they were associated with higher dissolved oxygen (DO) content in the water. Chironomus kiiensis, C. javanus and P. trigonus showed positive relationships with TOM, ammonium-N and nitrate-N as well as trace metals of Zn, Cu and Mn. These three species could be considered as tolerant species since they have the ability to survive in extreme environmental conditions with low DO and high concentrations of pollutants. Based on the water parameter scores in all rivers, the highest diversity of chironomid larvae was reported in CTKR. With higher concentrations of organic and/or inorganic pollutants as reported in PPR, KUR and AR, the chironomid larval diversity decreased, and the abundance of tolerant species, mainly Chironomus spp., increased.

Laboratory and field investigations of pestiferous Chironomidae (Diptera) in some man-made wetlands in central Florida, USA.

A 1-year larval and adult population survey of pestiferous chironomids was conducted in 4 man-made wetlands in a resort area of central Florida, USA. Benthic samples were randomly collected from each wetland at least once every month. Geocoordinates, water depth, and physical composition of substrates at each larval sample location were noted. Adult midge populations were sampled weekly around the wetlands by employing 10 New Jersey light traps permanently placed in the area. Chironominae and Tanypodinae midges occurred in the larval and adult samples; a few Orthocladiinae were also taken. Among Chironominae, Chironomini (mostly Polypedilum spp., Cryptochironomus spp., Glyptotendipes paripes, and Goeldichironomus carus) and Tanytarsini (mostly Tanytarsus spp.), and some other Chironomidae were recorded. Tanypodinae were quantitatively not important. Monthly mean number of total adults per trap-night ranged from 23 in February to 211 in October. Annual mean larval density and range of total chironomids in the study wetlands amounted to 1,128/m2, range: 0-12,332/m2. The total larvae were most abundant in May. Tanytarsus spp. and Polypedilum spp. were numerically the most predominant spatially as well as temporally. Mean water depth at the sampled locations was 1.83 m (range: <1-8.75 m); 47% of the total collected larvae occurred at <1-m water depth and 53% at >1-m-deep water. Of all sampled locations, substrates such as sand, mixed substrates, and muck were respectively encountered at 656, 371, and 299 locations. The predominance of sand and mixed substrates was conducive to supporting the numerically dominant Tanytarsus spp. and Polypedilum spp. In laboratory bioassays, Tanytarsus spp., Polypedilum spp., Glyptotendipes paripes, and Goeldichironomus carus were highly susceptible to temephos, as well as to s-methoprene. Bacillus thuringiensis serovar. israelensis was most effective against Tanytarsus spp. and least against Goeldichironomus carus.

Life tables study of immature Aedes albopictus (Skuse) (Diptera : Culicidae) during the wet and dry seasons in Penang, Malaysia.

Life tables were constructed for twelve cohorts of immature stages of the dengue vector Ae. albopictus in a wooded area of Penang, Malaysia. The development time of Ae. albopictus ranged from 6 to 10 days depending on the mean environmental temperature (r = - 0.639, p < 0.05). Total cohort mortality was correlated with total development time (r = 0.713, p < 0.05) but not temperature (r = -0.477, p > 0.05). Rainfall was correlated with neither development time (r = 0.554, p > 0.05) nor mortality (r = 0.322, p > 0.05). There was a significant difference among the total mortality that occurred in the twelve cohorts (H = 119.783, df = 11, p < 0.05). There was also a significant difference in mortality among the different stages (H = 274.00, df = 4, p < 0.05).