Aedes mosquitoes: the investigation of mosquito breeding sites

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3. Sampling method

The sampling activities has been carried out from 16 November 2013 until 19 January 2014. The field surveys were done once per week in each study area between 1000 h and 1500 h by person. Each survey consisted of the inspection of domestic and non-domestic areas of each 7 checkpoint selected study areas for water holding containers.

All types of water-filled including wet and dry containers that could act as potential breeding sites and were positive for mosquito larvae/pupae were recorded. The sampled containers (e.g. bottles, cups, buckets, tyres, tree hole, bottles, coconut shell) were described and categorized according to capacity (based on container size), type (plastic, glass, metal, natural, rubber, glass, polystyrene) and usage (discarded, kept, cover, water storage, domestic use, gardening). Other particulars of the location in which a container was found, such as whether it was a shaded or un-shaded and sunny or unsunny location. Location of container to be found also has been describe based on front, backyard, and side of premises. However beach excluded from the categorization as it focuses onto the beach yard.

The containers were categorized into three sizes: small (capacity < 1 litre), medium (1 litre < capacity < 10 litres) and large (capacity > 10 litres). Sampling methods for the all container categories are the same. For the positive containers, the Aedes immature (pupae and larvae) were collected using pipette or sieves and placed into test tubes. Only several random immature is taken to identify the species of mosquitoes breed in the particulars container. The samples taken were also tagged with the related check point so the container could be linked to the origin sample taken for forward purposes. The picture of all container also has been captured as evidence the present of container.

The container also is recorded as it located under the shading structures such as trees, roof, or cover. By this categories, the container should be classified as located at shaded area or unshaded area. By this categories, it will show the human behaviour that litter the container most.

The immature captured from 8-10. Then they were transported to the laboratory at the School of Biological Sciences, Universiti Sains Malaysia on the same day they were collected for rearing and identification at mature stages. During the larva stage, they were fed buy yeast once a day as well as change the water inside the test tubes every 3 to 4 days. Immature present not the main purpose in this study thus the rearing only provide sources for immature to develop into adult stages only. The larvae then transform into pupae, then reared until the emergence of adults after which the adults were identified to species, sexed and subsequently killed. Reared larvae or pupae were given a pinch of larval daily.

Data analysis was performed using the Microsoft Excel and Statistical Package for Social Science (SPSS) Version 15.0 or older for Windows. All the data for positive water-holding and negative water-holding containers were used for statistical analysis.

4. Results

4.1 Analysis of container attributes

Tables show summary of containers surveyed at the Batu Feringghi study areas. There is 7 places that have been studied and were inspected for potential mosquito breeding sites. Moreover, we also found positive container with one or more Aedes breeding sites. Out of a total of 1416 water-holding containers with positive and negative immature present were observed throughout this study, 175 were found in beach (coastal area), 122 in chalet construction (urban coastal residential area), 200 in Baywatch, 138 in astaka (canoe and boat garage) and chalet, 302 in commercial area I (stall and small shop), 437 in commercial area II (inn and mini market), and lastly mosque area with 42 container. From the total of 1416 container sampled only 33 were found positive with Aedes immature which is 2.33%.

Most of the premises and tourist are have compound that usually used to keep various unused containers that can be potential breeding sites. The location of the breeding containers dumped will assist the resident and Ministry of Health inspector so that these locations can be given more attention/or targeted during control efforts by fogging or spraying control activities. Figure 4.1 show the percentage of location container distributed. The highest number of the positive outdoor containers was found in back side of the premises (48%), followed by front area (20%), and (19%) side of premises. Whereas the beach placed lowest number of containers was found at beach area. Beach is independent location whereby it doesn’t have any direction toward premises.

Figure 4.2 shows the percentages of the shaded and unshaded containers found in outdoor areas. Aedes mosquitoes preferred containers in shaded areas rather than those in open areas (Nur Aida, 2013). More than half of the outdoor positive containers (51%) were found in partially and shaded areas, with 35% shaded by shrubs or trees and 16% were partially or fully shaded by the roof of houses. Forty one percent (41%) of the containers were found in the open areas. Chi square test showed a significant difference in the number of container found in shaded and open areas (χ2 =, p<0.05).

Figure 4.3 shows the percentage of container observed during study at Batu Feringghi, Penang Island in relation to container types. The containers were classified into seven categories; plastic, metal, natural (coconut shell, flower sheath, tree holes, leaf and plant axils), cement/clay, glass, rubber and polystyrene. If any potential container to be found that not specified under those seven will be state as others. Plastic containers were far more abundant than any other category, representing 52.4% of the total which was followed by glass (27%), polystyrene containers (11.5% each), glass (17.2%), natural (7.3%), metal (5.4%) rubber (1.3%) and cement (1%). Others make up 4% of the percentages. A Chi square test showed a significant difference in the number of different container types found during study period (χ2 =, df =, p<0.05).

The most abundant positive container type in each study site was plastic containers and least abundant was cement or clay containers in (χ2 = , df =, p<0.05). Figure 4.6 shows the percentages of water holding containers by type at the seven sites.

Seven categories of containers were identified based on container usage: 1) kept containers (paint and cement buckets, aluminium cans usually for reuse); 2) discarded (discarded items, plastic bag, containers); 3) covers (canvases, plastic sheets, container covers or lids); 4) water storage (drums, buckets, tanks); 5) domestic uses (basin for washing purposes, flower vases, kitchen items, bowl, cups); 6) animal baths or drink dispensers and 7) gardening tools (flower pots, trays, plant watering pot).

Figure 4.1: Percentage location of container toward premises distribution in seven studies sites at Batu Feringghi

Figure 4.2: Percentages situation container in outdoor areas toward the closest premises in the seven study sites. Figure 4.3: Percentages of potential water holding containers by type at Batu Feringghi tourist area.

Figure 4.4: Percentages of discarded potential breeding container by usage at Batu Feringghi.

Figure 4.5: Percentage size container found in seven studies areas at Batu Feringghi tourist area.

In figure 4.4 discarded containers were the most abundant, second is gardening containers. House owner usually keep containers which have potential for reuse such large paint pail for water storage as well as basin function. Cover containers were the least abundant followed by domestic uses during this study (Figure 4.6); (χ2 =, df = 7, p<0.05). Meanwhile, animal bath were not found during ten week of studies. Percentages in all four sites (Figure 5.6); (χ2 =, df = , p<0.05).

Analysis of container sizes (figure 4.6) revealed significant variations in the frequency of container sizes inhabited by Aedes immature (Nur Aida 2013). Water holding containers have been categorized into three sizes, small, medium and large. Those with capacity less than 1 litre were referred to as small containers. Water holding containers with a capacity of more than one litre and less than 10 litres were classified as medium containers, whereas those with capacity of more than 10 litres were classified as large containers.

Out of the total 1416 potential holding water containers observed in Batu Feringghi tourist area, the small containers (94% or n=1325) were the most abundant containers, followed by large containers (4% or n=55) and medium containers (2% or n=36) (Figure 5.7). Chi square test showed that there was a significant difference in the number of containers in relation to size (χ2 = 299.215, df = 2, p<0.05).

Figure 4.6: Percentages of potential water holding containers by type in seven classified area in Batu Feringghi (Beach, Chalet construction, Baywatch, Astaka and chalet, commercial area I, commercial area II, Mosque and street)

Figure 4.7: Percentages of usage characteristic of potential container in seven studies area in Batu Feringghi (Beach, Chalet construction, Baywatch, Astaka and chalet, commercial area I, commercial area II, Mosque and street)

Figures 4.8: Overall percentages of usage in seven studies area in Batu Feringghi (discarded, kept, cover, water storage, domestic use, gardening)

4.2 Analysis of periodical container

Figure 4.9 show the numbers of container based on types for each week starting week 1, (16/11/2013) until week 10, (19/1/2014). The number of potential water holding container is different of each week shows the lot of diverse in human activities that causes induce the inconsistency in amount container deposited for each week. Plastic container shows the very slight difference every week as it representing the highest number of container found. The peak of containers found for plastic type is at week 7 which is 28th December 2013, while it lowest during week 1 at 16th November 2013.

For metal, the highest number container found is at week 2 and 3 (16th and 23rd November) while the lowest is at week 8 in 11th January 2014. For natural container the peak number at week 8 and 9 (4th and 11th January 2014) while the lowest at both week 1 and 7 (16th November 2013 and 28th December 2013). Cement and clay based container recorded none much different of changing in number for every week. The highest glass container found on week 10 and the lowest for this type found in week 1. For rubber containers show non numerical change for starting from week 2 (23rd November 2013) until week 10 as the week first non-shown any recorded container found. Polystyrene container recorded that at the highest in week 7 and the lowest at the first week and second week of studies. Others container in peak at week ten and lowest at second week.

Figure 4.10 show the number of container distribution for each studies site starting week 1, (16th November 2013) until week 10, (19th January2014). Beach show the highest number at week 2 (23rd November 2013) while the lowest at week 10 (19th January 2014). The second study sites was in chalet construction shows the highest container found on the 8th week of the survey. Meanwhile the Baywatch’s container

Figure 4.9: Numbers of container based on types for each week starting week 1, (16/11/2013) until week ten, (19/1/2014)

Figures 4.10: Number of container distribution for each studies site starting week 1, (16/11/2013) until week 10, (19/1/2014)

Figure 4.11: Percentages container found for each week starting week 1, (16/11/2013) until week 10, (19/1/2014).

found show highest at week 7 (28th December 2013) as the lowest is in week 2 (23rd November 2013). In astaka and chalet area the highest at week 6 and the lowest in week 5. In commercial area I (stall area, food shop) the highest number found in week 7 while the lowest found in week 9. The commercial area II shows the different with the highest container found in both week 4 and 10 and the lowest at week 1. The mosque and street area did not show the significant different between the each week of the container found.

Figure 4.11 shows that the overall percentages of the container found in seven studies area for temporal week. As the week 7 during 28th December 2013 is the highest percentages with 14.16% followed by week 6 with 11.93%. The 3rd highest is in week 4 with 10.95%. Both week 3 and 8 show the same percentages which is 10.1%. The lowest is in week 1 which only 5.44% followed by week 2 with 8.05%.

4.3 Analysis of positive container

Alongside the container found there is several container positively present of the mosquitos immature including Ae. aegypti, Ae. albopictus, Culex spp and Armigeres spp. From out of 1416 container recorded in ten week of studies 35 of them were positively immature represent only 2.47% of the total containers.

During the studies, week 4 (7th December 2013) recorded the highest places of immature present which is 6 while the lowest in week 7 (28th December 2013) with only one frequencies for that week.

Figures 4.12: Percentages of immature present in container found during ten week studies in Batu Feringghi

Figure 4.13: Number of positive container abundance during ten weeks studies in Batu Feringghi

Figure 4.14: Percentage of immature present in positive water container by species and breeding size

Date

Breeding site

Location

Species

Container size

16th November 2013

Coconut shell

Beach

Ae albopictus

Small

Cement crack

Commercial area I

Ae albopictus

Small

Paint pail

Commercial area II

Ae albopictus

Ae aegypti

Large

Date

Breeding site

Location

Species

Container size

23rd November 2013

Tyre

Chalet construction

Ae albopictus

Large

Coconut shell

Beach

Armigeres spp

Small

Cement crack

Commercial area I

Ae albopictus

Medium

Pot plate

Commercial area II

Ae albopictus

Small

Paint container

Commercial area II

Ae albopictus

Large

Date

Breeding site

Location

Species

Container size

30th November 2013

Plastic bowl

Commercial area I

Ae albopictus

Small

Cement crack

Commercial area I

Ae albopictus

Medium

Plastic snack

Construction chalet

Ae albopictus

Small

Paint pail

Commercial area II

Ae albopictus

Large

Date

Breeding site

Location

Species

Container size

7th December 2013

Plastic snack

Beach

Ae albopictus

Small

Plastic bread

Beach

Ae albopictus

Small

Plastic snack

Beach

Ae albopictus

Small

Cement crack

Commercial area I

Ae albopictus

Ae aegypti

Medium

Paint pail

Commercial area II

Ae albopictus

Large

Paint pail

Commercial area II

Ae albopictus

Large

Date

Breeding site

Location

Species

Container size

14th December 2013

Plastic bread

Beach

Ae albopictus

Small

Nuts frond

Commercial area I

Ae albopictus

Small

Paint pail

Commercial area II

Ae albopictus

Large

Paint pail

Commercial area II

Ae albopictus

Large

Date

Breeding site

Location

Species

Container size

21st December 2013

Plastic snack

Beach

Ae albopictus

Small

Plastic bread

Beach

Ae albopictus

Small

Paint pail

Commercial area II

Ae albopictus

Large

Paint pail

Commercial area II

Ae albopictus

Large

Date

Breeding site

Location

Species

Container size

28th December 2013

Tyre

Astaka and chalet

Ae aegypti

Large

Date

Breeding site

Location

Species

Container size

4th January 2014

Tyre

Astaka and chalet

Ae albopictus

Large

Paint pail

Commercial area II

Ae albopictus

Large

Date

Breeding site

Location

Species

Container size

11th January 2014

Tyre

Astaka and chalet

Ae albopictus

Large

Stuck drain

Commercial area II

A albopictus

Culex spp

Medium

Paint pail

Commercial area II

Ae albopictus

Large

Date

Breeding site

Location

Species

Container size

19th January 2014

Tyre

Astaka and chalet

Ae albopictus

Large

Stuck drain

Commercial area II

Ae albopictus

Culex spp

Medium

Paint pail

Commercial area II

Ae albopictus

Large

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