Acaricidal activity of Cymbopogon citratus and Azadirachta indica against house dust mites

Objective:To examine the acaricidal effects of the essential oil of Cymbopogon citratits leaf extract(lemongrass)and ethanolic Azadirachta indica leaf extract(neem)against house dust mites Dermatophagoides farinae(D.farinae)and Dermalophagoides pteronyssinus(D.pteronyssinus).Methods:Twenty-five adults mites were placed onto treated filter paper that is soaked with plant extract and been tested at different concentrations(50.00%,25.00%,12.50%,6.25%and 3.13%)and exposure times(24hrs,48hrs,72hrs and 96 hrs).All treatments were replicated 7 times,and the experiment repeated once.The topical and contact activities of the two herbs were investigated.Results:Mortalities from lemongrass extract were higher than neem for both topical and contact activities.At 50%concentration,both 24 hrs topical and contact exposures to lemongrass resulted in more than 91%mortalities for both species of inites.At the same concentration and exposure time,neem resulted in topical mortalities of 40.3%and 15.7%against D.pteronyssinus and D.farinae respectively;contact mortalities were 8.0%and 8.9%against the 2 mites,respectively.There was no difference in topical mortalities of D.pteronyssinus from exposure to concentrations oflemongrass and neem up to 12.50%;lemongrass was more effective than neem at the higher concentrations.Conclusions:Generally,topical mortalities of D.farinae due to lemongrass are higher than that due to neem.Contact mortalities of lemongrass are always higher that neem against both species of mites.

Establishment of a molecular tool for blood meal identification in Malaysia

Objective:To establish a polymerase chain reaction(PCR) technique based on cytochrome b {cytb) gene of mitochondria DNA(mtDNA) for blood meal identification.Methods:The PCR technique was established based on published information and validated using blood sample of laboratory animals of which their whole gene sequences are available in CenBank.PCR was next performed to compile gene sequences of different species of wild rodents.The primers used were complementary to the conserved region of the cytb gene of vertebrate's mtDNA.A total of 100 blood samples,both from laboratory animals and wild rodents were collected und analyzed.The obtained unknown sequences were compared with those in the GenBank database using BLAST program to identify the vertebrate animal species.Results:Gene sequences of 11 species of wild animals caught in 9 localities of Peninsular Malaysia were compiled using the established PCR. The animals involved were Rattus(rattus) tanezumi,Rattus tiomanicus,Leopoldamys sabanus, Tupaia glis,Tupaia minor,Niviventor cremoriventor,Rhinosciurus laticaudatus,Calloseiurus caniseps,Sundamys muelleri,Rattus rajah,and Maxomys whitelwadi.The BLAST results confirmed the host with exact or nearly exact matches(>89%identity).Ten new gene sequences have been deposited in CenBank database since September 2010.Conclusions:This study indicates that the PCR direct sequencing system using universal primer sets for vertebrate cytb gene is a promising technique for blood meal identification.

Acarine ectoparasites of Panti Forest Reserve in Johore,Malaysia

Objective:To identify the presence of acarine ectoparasites and determine whether there is any potential public health risk in Panti Forest Reserve,Johore,Malaysia.Methods:Trapping of animals and avifauna was conducted simultaneously along 5 expedition trails using 150 wire traps,10 harp traps and 30 mist nets for 6 consecutive nights.A total of 140 animals consisting of 7 species of birds,19 species of bats,6 species of rodents and 1 species of tree-shrew as well as 8 myriapods were examined.Results:Infestation rates of ticks,mesostigmatid mites and chiggers on animals examined were 24.3%,28.6%and 27.9%,respectively.Infestation on bats was low(1.5%) and none occurred on birds.Majority of ticks extracted were at immature stages(78.9%). Genera of ticks on animals were Amblyomma,Dermacentor,Haemaphysalis and Ixodes.Ixodes granulatus was the only species of licks identified from the animals.Examination of ticks under vegetation revealed 54%adults leading to identification of 3 species of ticks.A total of 7 species of mesostigmatid mites were found.6 species were on rodent,Maxomys mrifer and another one species,Laelaps nuttalli was found only on Leopoldamys sabanus.Laelaps sanguisugus was the only mesostigmatid found infesting tree-shrews.Seven genera of chiggers were identified.From this,5 genera were on rodents,4 genera on tree-shrews and 1 genus on a bat.Conclusions:A total of 16 genera,2 sub-genus and 14 species of acarine ectoparasites were found in this area. Findings of the survey demonstrate the presence of three spesies of acarine ectoparasites which have potential health risk i.e.Ixodes granulalus,Laelaps nuttalli and Leptotrombidium deliense.

Distribution of arthropods in rice grains in Malaysia

Objective:To determine distribution of arthropods in rice grains obtained from different sources.Methods: Rice samples were randomly collected from public in urban areas,farmers in rice field areas,aborigines in undeveloped areas and retailers in commercial premises.Random samples of rice were taken out from each sample for isolation of arthropods using a modified Berlese Tullgren Funnel Method.Mites were mounted prior to identification; weevils were directly identified.Results:Samples of rice from retailers in commercial premises had the highest infestation by arthropods followed by samples from urbanites,aborigines and rice farmers.Two species of weevils,Sitophilus oryzae(S.oryzae) and Sitophilus granarius(S.granarius),were found.Samples from commercial premises had the least percentage of weevils compared to those collected from domestic premises. Depending on the source of samples,densities of S.granarius and S.oryzae ranges from 11-103 weevils/ kg and 7- 80 weevils/kg,respectively.Important species of mites in stored rice identified were mainly members of the families Cheyletidae,Echimyopodidae,Pyroglyphidae,Saproglyphidae and Tenuipalpidae.Among the species of mites identified were Austroglycyphagus malaysiensis,Cheyletus fortis,Cheyletus malaccensis,Dermatophagoides pteronyssinus,Grammolichus malukuensis and Suidasia pontifica.Average density of most of the mites was less than 40 mites/kg of rice grains.In this study,the highest number of mites in rice samples was recovered from commercial premises,followed by samples from urbanites.Samples from farmers and aborigines contained lesser mites.Conclusion:This study demonstrated the presence of 3 allergenic mite species in rice, i.e A.malaysiensis,D.pteronyssinus and S.pontifica.Weevils,S.oryzae and S.granarius that are known to be allergenic,were also found.

Effect of a commercial air ionizer on dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae(Acari:Pyroglyphidae) in the laboratory

Objective:To investigate the short and long tenn efficacy of a commercial air ionizer in killing Dermatophagoides pteronyssinus(D.pteronyssinus)and Dermalophagoides farinae(D.farinae)mites.Methods:The effect of a commercial ionizer on D.pteronyssinus and D.farinae was evaluated in the laboratory,using a specially designed test.Mortality was assessed after 6,16and 24 hours for direct exposure and after 24,36,48,60 and 72 hours for exposure in simulated mattress.New batches of mites were used for each exposure time.Results:LT_(50)for direct exposure of ionizer was 10 hours for D.pteronyssinus and 18 hours for D.farinae.The LT_(50)for exposure in simulated mattress was 132 hours or 5.5 days for D.pteronyssinus and 72 hours or 3days for D.farinae.LT_(95)for direct exposure of ionizer was 36 hours for D.pteronyssinus and D.farinae.Meanwhile,the LT_(95)for exposure in simulated mattress was 956 hours or 39.8 days for D.pteronyssinus and 403 hours or 16.8 days for D.farinae.Conclusions:This study demonstrates the increasing mite mortalities with increasing exposure time of a commercial ionizer and suggests that negative ions produced by an ionizer kill dust mites and can be used to reduce natural mile populations on exposed surfaces such as floors,clothes,curtains,etc.However,there is reduced efficacy on mites inside stuffed materials as in mattresses and furniture.

Effect of germicidal UV-C light(254 nm)on eggs and adult of house dustmites,Dermatophagoides pteronyssinus and Dermatophagoides farinae(Astigmata:Pyroglyhidae)

Objective:To examined the immediate and 24 hours post-irradiation germicidal effects of UV-C lamp on.eggs and adults of house dust mites Dermatophagoides pteronyssinus(D.pteronyssinus)and Dermatophagoides farinae(D.farinae).Methods:This study investigated the immediate and24 hours post irradiation mortalities of adult mites exposed to UV-C at different exposure times(5mins,10 mins,15 mins,20 mins,30 mins and 60 mins)and distances(10 cm,25 cm,33 cm,45 cm and 55 cm).Fresh eggs of the 2 dust mites were also irradiated at 10,35 and 55 cm for 0.5,1,2,3,and 5 minutes,and observed daily post-irradiation for up to 7 days.Results:Highest immediate mortality of 100%occurred with direct irradiation al 10 cm distance from UV-C lamp and for 60mins,for both species of mites.The post 24 hours mean mortality rates were(58.4±17.4)%for D.pteronyssinus and(27.7±9.7)%for D.fitrinae when irradiated for 1 hour at 55 cm distance under UV-C lamp.When mites were irradiated in the presence of culture media,the highest mortality rates were lower compared to the direct irradiation;at 10 cm distance and 60 mins exposure,the mean mortality was(74.0±6.8)%for D.pteronyssinus and(70.3±6.7)%for D.farinae.Egg hatchability for both species of mites was also notably reduced by greater than 50%following irradiation.Conclusions:Ultraviolet C irradiation is lethal to an array of organisms by damaging their nucleic acids(DNA and RNA).This study demonstrates the increasing mite mortalities with increasing exposure times and decreasing distances.

Precise identification of different stages of a tick,Ixodes granulatus Supino,1897(Acari:Ixodidae)

Objective: To identify different stages of Ixodes granulatus(I. granulatus) based on morphological characters prior to molecular identification which is significant for confirming and identifying the nymphal stages of I. granulatus.Methods: A total of 14 individuals of adult, engorged and nymphal ticks collected from three different localities were examined morphologically using taxonomic keys, followed by PCR using cytochrome oxidase subunit I(COI). Clustering analysis based on COI sequences was carried out by constructing neighbor-joining and maximum parsimony tree to clarify the genetic variation and diversity of local I. granulatus.Results: Based on external morphological characterizations, nine individuals(64.3%)were successfully identified as I. granulatus, while five individuals were recognized only as Ixodes sp. due to lack of morphological characters visible and development during that stage. Molecular analysis of local I. granulatus using COI gene revealed 93%–94% sequence homology from available sequence in Gen Bank and was in concordance with the morphological identification. Furthermore, a low intraspecific variation was observed among the species of I. granulatus collected from different localities(0%–3.7%).Conclusions: These findings demonstrated for the first time the establishment of COI gene for identifying I. granulatus nymphal tick which is of paramount importance to the control of potential tick-borne infections in Malaysia. Moreover, this study provides evidence that a combination of morphology and molecular data was corroborated as an accurate tool for tick identification.

The occurrence of arthropods in processed rice products in Malaysia

Objective:To determine distribution of arthropods in processed rice products such as rice flour and rice cereal-based infant food.Methods:Random samples of rice flour and rice cereal-based infant food purchased from commercial outlets were examined for the presence of arthropods using a modified Berlese Tullgren Funnel Method.Mites were mounted prior to identification and weevils were directly identified.Results:For non-expired products, infestation was found in 6.7%of rice flour and none was found in rice cereal-based infant food samples.The arthropods found in the flour samples were Cheyletus spp.,Suidasia pontifica(S. pontifica),Tarsonemus spp.,Tyrophagus putrescentiae(T.putrescentiae),Sitophilus granarius(S. granarius) and Sitophilus oryzae(S.oryzae).Others which cannot be identified were Oribatid and Prostigmatid mites.The most common mites in rice flour were Tarsonemus spp.(69.1%),followed by S.pontifica(18.2%).For expired products,only one sample of rice cereal-based infant food was infested and the infestation was by mites of the family Tydeidae.Conclusions:This study demonstrates the presence of 4 allergenic species of S.pontifica,T.putrescentiae,S.granarius and S.oryzae in rice flour.These arthropods can contribute to the incidence of anaphylaxis upon consumption by atopic individuals.There was no infestation of arthropods in rice cereal-based infant food surveyed except for an expired product in a moderate rusty tin container.

Movements and home range of a common species of tree-shrew,Tupaia glis,surrounding houses of otoacariasis cases in Kuantan,Pahang,Malaysia

Objective:To document movement patterns,home range,nesting behaviour and social organization of 5 individuals(3 males and 2 females) of a common species of tree-shrew,Tupaia glis(T.glis) surrounding houses of otoacariasis cases.Methods:Each shrew was fitted with a transmitter chip radio-collar which operates between the frequencies of 154.13 MHz to 154.21 MHz.Each transmitter was then tracked with a Portable Telemetry Receiver(Sirtrack,New Zealand) fitted with a 3-element Yagi antenna.Collared shrews were located using standard methods of ground-based triangulation.Each location was taken from at least 2 directional fixes and a minimum of 3 compass bearings.Fixes were taken hourly for each collared individual from the time of emergence from nest(beginning of activity) till time of entry into the nest(end of activity) every day for 5 to 7 continuous days.Three series of radio telemetry observations were carried out.The bearings,time and positions of an observer were recorded and later plotted on a graph paper in order to derive coordinates of the collared animal.[These coordinates then analyzed using Ecological Software Solutions(Biotas Version 1.03)].Results:Nests were found in a jack fruit tree,long bushes,and 2 houses.Daily telemetry detections demonstrated 2 individuals of different sex having nests(or a nest) in the same house.All shrews emerged from and returned to their nests between 0601 to 0659 hours and 1901 to 1959 hours,respectively. Both the time of exit from and entry into nest were the same between sexes(P】0.05).Their average total active period was 4.90 to 7.00 hours with a total daily travel distant of 270 m to 382 m.A male and a female shrew can move as far as 3 285 m and 4 591 m,respectively.Active movements of T.glis were during daytime.They regularly entered some houses in the area during day and night except for one individual which visited during daytime only.The sizes of home range and core area for the shrews were 2.00-3.40 ha and 0.05-0.42 ha,respectively.Generally, the mean home range size of females was 20.8%larger than that of males.Females covered a 15.4%slightly higher daily movement range compared to males.Conclusions:This is the first radio telemetry study in Malaysia to monitor movements and home range of shrews carrying ticks on their body.It demonstrates that shrews are potential carriers of ticks from wild into the houses and their compounds based on their total active periods spent moving around from fruit orchards, secondary forest,plantations and other vegetations to trees in compound of 4 to 7 houses and vice versa.There are also evidences showing shrews have close contact with humans.