Population abundance of Aedes albopictus and culex quinquefasciatus in 24 hours cycle in residential areas, penang using different trapping methods

The increasing concern on the current activity of Aedes albopictus and Culex quinquefasciatus mosquitoes as pest and diseases vector in the residential areas require thorough and immediate evaluation. Therefore, 24 hours trapping was conducted at the urban Sungai Dua and sub-urban Batu Maung residence area, Penang, Malaysia, using two different traps; BG- Sentinel Trap and CDC Fay-Prince Light Trap under two different light conditions to investigate the possibility effect of light to both mosquito species. CDC Fay-Prince light trap was effective in trapping Cx. quinquefasciatus than BG–Sentinel traps. The results indicated that both traps were ineffective to capture Ae. albopictus. In this study, the peak activity of Ae. albopictus was not following the diel host-seeking activity which this species active at daylight (6:00am–8:00am) and during night time (6:00pm–8:00pm). Whereas, Cx. quinquefasctus was captured mostly during the nocturnal time (12:00am–6:00am) with a greater number of Cx. quinquefasciatus mosquitoes captured under no light conditions. Meteorological parameter recorded within experiment such as temperature, relative humidity, and wind speed did not correlate with the abundance of both mosquito species (p> 0.05). However, light intensity parameters significantly affected Cx. quinquefasciatus mosquito abundance in both residential areas (p= 0.002), but not the Ae. albopictus mosquitoes (p= 0.086 Sungai Dua; p= 0.803 Batu Maung) as light is not a primary cue attraction factor to any host source towards this species. Ovitraps seem to be better tools for collecting and surveillance population of Ae. albopictus mosquitoes as compared to BG- Sentinel trap (Paired t-test; p= 0.019) and CDC Fay-Prince light trap (Paired t-test; p= 0.025). As a conclusion, BG-Sentinel trap and CDC Fay-Prince light traps is a not suitable tool for monitoring the activities of Ae. albopictus in the residential area, but CDC Fay-Prince light traps still found effective to use to capture Cx. quinquefasciatus. This study has therefore established immature sampling as the most effective method of capturing Ae. albopictus in a residential area

Multifarious roles of feeding behaviours in rove beetle, Paederus fuscipes

The rice green leafhopper Nephotettix virescens Distant (Hemiptera: Cicadellidae), zigzag leafhopper Recilia dorsalis Motschulsky (Hemiptera: Cicadellidae), and brown planthopper Nilaparvata lugens Stål (Hemiptera: Delphacidae) are the most economically important insect pests infesting rice crop. Paederus fuscipes Curtis has been reported as the natural predator for these rice pest species in Southeast Asia. Under laboratory conditions, we evaluated the prey preference of this generalist predator when it encountered the three main agricultural pests of rice plant. P. fuscipes typically displayed a Type II functional response for all prey species. However, at high prey densities they consumed predominantly R. dorsalis with highest attack rate on dead R. dorsalis prey. Conversely, significantly highest time was needed to handle live R. dorsalis. When various density of preys was tested simultaneously, the predator showed greater preferences towards R. dorsalis and Ni. lugens. We observed the behavioral response of P. fuscipes predator on its prey items. Highest number of searching and capturing attempt was most frequently displayed on live Ni. lugens prey species. Whereas, P. fuscipes spent more feeding time in consuming dead prey compared to the alive ones. Overall, P. fuscipes showed successful control of small and soft body crop pests at low prey density

The Influence of Mosquito Predators on Population Dynamics of Endemic and Exotic Mosquitoes

The presence of predators can shape the population dynamics of prey. Here, I evaluated the influence of predators on mosquito populations by direct effects through predation, and indirect effects through sub-lethal responses. The predator under investigation was the backswimmer Anisops wakefieldi. I first quantified the relationship between mosquito and predator populations in animal drinking water troughs, and correlated their abundance with water volume and environmental factors. Logistic regression indicated that the presence of mosquitoes was primarily affected by three factors; predator numbers, week of observation, and water volume. A translocation experiment was established to understand the pre- and post-treatment effects on mosquito survival after exposure to the predator Anisops wakefieldi. The presence of these predators in water troughs significantly decreased subsequent survival of mosquito prey within two days posttranslocation. A major hypothesis in invasion ecology suggests that native predators have less impact on exotic species relative to native prey species, enabling exotic species to establish and thrive in novel environments. This is the "escape from natural enemies" hypothesis. Contrary to this hypothesis A. wakefieldi, a native New Zealand predator, showed a greater preference, and consumed more of the exotic mosquito Aedes (Ochleratatus) notoscriptus compared to the native (Culex pervigilans) mosquito larvae. Anisops wakefieldi exhibited a decelerating Type II functional response for both prey species, but consumed more exotic mosquito species at high prey densities and displayed higher attack rates. The effects of the preference of this predator on mosquito behaviour were examined. In the presence of predators the exotic species, Ae. notoscriptus, demonstrated significantly higher levels of "thrashing" behaviours, apparently making itself more obvious to the predators. In contrast Cx. pervigilans fulfilled the "threat sensitivity" hypothesis by altering its behaviour towards "resting", known to be the best strategy for avoiding predators. In addition to lethal effects, predators can substantially alter prey populations by means of sub-lethal influences. To further our understanding of how predators limit mosquito abundance, I developed an experiment based on adult mosquito oviposition. I predicted that the New Zealand native mosquito, Cx. pervigilans would likely avoid containers with A. wakefieldi or their kairomones. Contrary to our predictions, Cx. pervigilans appeared to ignore the presence of predators and their kairomones when choosing oviposition habitats and the number of egg rafts was not significantly affected by the density of predators. Culex pervigilans eggs from the oviposition experiment were reared in two different laboratory conditions: (A) in clean water without any traces of predators, or (B) in water with the same treatments as in field. This experiment was established in order to have better understand on what happens to the next generation after exposure to A. wakefieldi predators or their kairomones. Sub-lethal effects were still apparent in the developing larvae. I observed a significant reduction in the survival rate of Cx. pervigilans in the presence of predators and their kairomones, even when the eggs were only exposed briefly to water containing either predators or kairomones in the field, and were then reared in clean water without any traces of the predator. No effect was observed on the sex ratio of Cx. pervigilans, or the development times of each life stage. Overall, this thesis has highlighted the importance of predators in influencing mosquito populations, not only through direct predation, but also in indirect and sub-lethal ways. This study may have implications for the dynamics of other predator-prey systems. Despite this, we are only beginning to understand the complex interactions between predators and prey

Efficacy of different parts of Tridax procumbens as a potential biolarvicide against Aedes aegypti and Aedes albopictus

The epidemic of dengue and Zika outbreak transmitted by Aedes mosquitoes has been a global issue and plenty of preventive measurements are being used. Due to environmental awareness, people are opting on bioinsecticide. The objective of this research is to study on the effectiveness of different parts of Tridax procumbens plant on Aedes aegypti and Aedes albopictus larvae. Tridax procumbens are endemic plants in Malaysia. Using WHO standard larval bioassay, third instar larvae of Ae. aegypti and Ae. albopictus were exposed to different concentrations, ranging between 250ppm-2500ppm for three different parts of T. procumbens plant extracts obtained from Soxhlet extraction. Larval mortality was observed after 24-hour exposure. The highest toxicity for Ae. aegypti was recorded by T. procumbens stem extract with the LC50 of 799.78ppm. The pairwise comparison showed, the highest mean mortality value for stem did not show any significant difference with leaves; however, it did show a significant difference with flowers when tested on Ae. aegypti (P<0.05). Meanwhile for Ae. albopictus, the highest toxicity recorded with the LC50 of 583.63ppm was by the T. procumbens flower extract. The mean mortality value for flower showed significant differences from other plant parts when tested on Ae. albopictus (P<0.05). This indicates that T. procumbens is effective in killing both Ae. aegypti and Ae. albopictus

Attraction factors for Paederus fuscipes ' dispersal, a vector of Paederus dermatitis towards human residential premises

Paederus fuscipes, a vector of Paederus dermatitis in most tropical and subtropical countries of the world have a high prevalence in human dwellings due to their positively phototaxic behaviour which has caused a tremendous impact on human health. In this paper, P. fuscipes dispersal flights were studied for two seasons of the rice cultivation phases in residential premises built close to rice field areas (≈32-60 m and 164 m) in mainland Penang, Malaysia. We examined the effects of different light illuminance, building floor level and their association with rice stages as a focal cause of P. fuscipes dispersion from the rice fields towards human dwellings. The present study showed a significant interaction between different light illuminances and rice cultivation phases in attracting P. fuscipes to disperse and invade human dwellings. The highest number of P. fuscipes was captured near the bright light. P. fuscipes flights increased in line with each floor level, and the highest captures took place at higher building floor levels (levels 2 and 3) compared to lower building floor levels (ground floor and level 1) of a three storey apartment in both rice seasons. This finding not only conveys a better understanding on P. fuscipes dispersal pattern, but also draws public attention on the occurrence of dermatitis linearis caused by the Paederus beetles

Evaluations of entomopathogenic fungi, Metarhizium anisopliae inoculate on the treated soils towards Paederus fuscipes

Rove beetle, Paederus fuscipes Curtis is a natural predator of several crop pests in the agriculture ecosystem, however, their high intrusion into human settlements caused them to become public health concern due to Paedarus dermatitis infection among humans. The entomopathogenic effectiveness of Metarhizium anisopliae Mechnikov was tested as biological control towards adults Paederus fuscipes by inoculating on soils. The mortality of P. fuscipes was observed and data were subjected to analysis using ANOVA and Kaplan-Meier method. Results show that P. fuscipes tested with the highest concentration at 1.3 × 1010 conidia/mL exhibited the shortest mean mortality time at 11.0 ± 2.5 days and survival time of 7.6 ± 0.7 days, yet the secondhighest concentration exhibited at 2.2 × 109 showed mean mortality of 18.4 ± 4.2 days and survival time of 11.9 ± 0.8 days. Log Rank (Mantel-Cox) pairwise comparison indicated the significant differences between the highest concentration of 1.3 × 1010 with the control (χ2 = 62.3, df=1 p<0.0005). Both mean mortality time and survival time of P. fuscipes showed inconsistent trends from the highest concentration of M. anisopliae towards the lowest. Pathogenicity was observed at the concentrations of 106, 109, and 1010 after performing Koch’s postulates. The results were unexpected but could indicate that M. anisopliae has the potential to be a biocontrol agent at a higher concentration

Assesstment of residual bio-efficacy and persistence of Ipomea cairica plant extract against Culex quinquefasciatus Say mosquito

Specification on residual action of a possible alternative insecticide derived from plant materials is important to determine minimum interval time between applications and the environmental persistence of the biopesticides. The objective of this study is to evaluate crude acethonilic extract of Ipomoea cairica leaves for its residual and persistence effects against Culex quinquefasciatus larvae. Wild strain of Cx. quinquefasciatus larvae were used for the purpose of the study. Two test designs, replenishment of water and without replenishment of water were carried out. For the first design, a total of 10 ml of test solution containing Ip. cairica extracts was replenished daily and replaced with 10 ml of distilled water. For the second design, treatment water was maintained at 1500 ml and only evaporated water was refilled. Larval mortality was recorded at 24 hours post-treatment after each introduction period and trials were terminated when mortality rate falls below 50%. Adult emergences from survived larvae were observed and number of survivals was recorded. For the non-replenishment design, mortality rate significantly reduced to below 50% after 28 days, meanwhile for replenishment of water declined significantly after 21 days (P < 0.05). There was no adult emergence observed up to seven days for non-replenishment and first two days for replenishment of water design. The short period of residual effectiveness of crude acethonilic extract of Ip. cairica leaves with high percentage of larval mortality on the first few days, endorses fewer concerns of having excess residues in the environment which may carry the risk of insecticide resistance and environmental pollution

Assessment of residual bio-efficacy and persistence of Ipomoea cairica plant extract against Culex quinquefasciatus Say mosquito

Specification on residual action of a possible alternative insecticide derived from plant materials is important to determine minimum interval time between applications and the environmental persistence of the biopesticides. The objective of this study is to evaluate crude acethonilic extract of Ipomoea cairica leaves for its residual and persistence effects against Culex quinquefasciatus larvae. Wild strain of Cx. quinquefasciatus larvae were used for the purpose of the study. Two test designs, replenishment of water and without replenishment of water were carried out. For the first design, a total of 10ml of test solution containing Ip. cairica extracts was replenished daily and replaced with 10ml of distilled water. For the second design, treatment water was maintained at 1500ml and only evaporated water was refilled. Larval mortality was recorded at 24 hours post-treatment after each introduction period and trials were terminated when mortality rate falls below 50%. Adult emergences from survived larvae were observed and number of survivals was recorded. For the non-replenishment design, mortality rate significantly reduced to below 50% after 28 days, meanwhile for replenishment of water declined significantly after 21 days (P < 0.05). There was no adult emergence observed up to seven days for non-replenishment and first two days for replenishment of water design. The short period of residual effectiveness of crude acethonilic extract of Ip. cairica leaves with high percentage of larval mortality on the first few days, endorses fewer concerns of having excess residues in the environment which may carry the risk of insecticide resistance and environmental pollution

Coffee and its waste repel gravid Aedes albopictus females and inhibit the development of their embryos

Background Dengue is a prevalent arboviral disease and the development of insecticide resistance among its vectors impedes endeavors to control it. Coffee is drunk by millions of people daily worldwide, which is associated with the discarding of large amounts of waste. Coffee and its waste contain large amounts of chemicals many of which are highly toxic and none of which have a history of resistance in mosquitoes. Once in solution, coffee is brownish in colour, resembling leaf infusion, which is highly attractive to gravid mosquitoes. To anticipate the environmental issues related to the increasing popularity of coffee as a drink, and also to combat insecticide resistance, we explored the deterrence potentials of coffee leachates against the ovipositing and embryonic stages of the dengue vector, Aedes albopictus. Methods In a series of choice, no-choice, and embryo toxicity bioassays, we examined changes in the ovipositional behaviours and larval eclosion of Ae. albopictus in response to coffee extracts at different concentrations. Results Oviposition responses were extremely low when ovicups holding highly concentrated extract (HCE) of coffee were the only oviposition sites. Gravid females retained increased numbers of mature eggs until 5 days post-blood feeding. When provided an opportunity to oviposit in cups containing coffee extracts and with water, egg deposition occurred at lower rates in those containing coffee, and HCE cups were far less attractive to females than those containing water only. Females that successfully developed in a coffee environment preferentially oviposited in such cups when in competition with preferred oviposition sites (water cups), but this trait did not continue into the fourth generation. Larval eclosion occurred at lower rates among eggs that matured in a coffee environment, especially among those that were maintained on HCE-moistened substrates. Conclusions The observations of the present study indicate a pronounced vulnerability of Ae. albopictus to the presence of coffee in its habitats during the early phases of its life cycle. The observations that coffee repels gravid females and inhibits larval eclosion provide novel possibilities in the search for novel oviposition deterrents and anti-larval eclosion agents against dengue vectors.This work was supported by funds (No. 096010) from the Central Research Institute of Fukuoka University and “Long Term Research Grant (LRGS) for Infectious Diseases, 2011 – 2014, Ministry of Higher Education, Malaysia” and USM (304/Pbiology/650575/U112)

Green tea and its waste attract workers of formicine ants and kill theirworkers—implications for pest management

Daily, 3 billion cups of tea consumed worldwide and this consumption is accompanied by the discardingof huge waste amounts into the environment. Tea leaf contains a diverse array of toxic molecules. Despiteevidence that its waste is almost as rich in toxicants as green leaves; no research has been done to turnthis source of pollution into a benefit for ant pest management, where new chemistries are highly neededas a result on insecticide resistance. The present study was performed to explore the behavioral and lethaleffects of tea and its leftovers on the black crazy ant (BCA), Paratrechina longicornis Latreille, yellow crazyant (YCA), Anoplolepis gracilipes Smith, and weaver ant (WA), Oecophylla smaragdina Fabricius. Both freshtea extract (FTE) and used tea extract (UTE) were detrimental to the survival of BCA, YCA, and WA. FTEwas the most toxic solution and BCA was the most vulnerable species. The presence of tea extracts inmeals did not prevent workers of all three species from visiting and feeding in the presence their preferredfoods. The results presented here suggest that diets containing tea extracts are attractive to BCA, YCA, andWA when in competition with their preferred foods. These extracts were also insecticidal to the workerants. These properties demonstrate the potential of tea and its waste products for developing novelenvironmentally friendly and low-cost ant control strategies, which could also be a practical solution tothe growing environmental problem it causes