Setting the OL Trap - DepEd Naga City

Objective 

• General 

‣ Provide the scientific framework of the OL 

Trap Program of Dengue vector control 

UITO OL-TRAP 

15 June 2012 DOST School-based O/L Trap Program 

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Objective 


• Specific 

‣ Explain the concept of vector control 

‣ Explain dengue vector control 

‣ Explain Integrated Vector Control (IVC) and 

Integrated Vector Management (IVM) 

‣ Discuss the components of IVC from vector 

biology to control measures 


3

Objective 

• Specific 

‣ Describe vector surveillance as it applies to 

dengue OL Trap in a classroom setting 

‣ Answer the fourteen questions enumerated 

in the situationer 



4

Objective 


• Specific 

‣ Identify the following 

• Mosquito eggs in a lawanit paddle 

• Ovitrap (black tumbler and paddle) 

• Mosquito larva 

• Pupae 

• Positive/negative trap 

• Adults 

• Entomological forms (Ovitrap/OL Trap) 

• Pellets 


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Situationer 


• Urban / semi-urban setting 

• Big public elementary school in City “X” 

• 3-story building (~30-35 feet) 

• 10 classrooms per floor 16x20 feet per 

room) 

• 50-55 pupils occupy one classroom from 

8am-5pm 


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Situationer 


• ~ 1,200-1,500 pupils 

• No electric fans in the classrooms 

• One aircon and/or electric fan at 

principal’s office 

• Houses near the school 

• Presence of flower vases, water 

containers 

Click Here 


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Questions 


• How many ovitraps/OL Traps are 

needed to be installed in the 

elementary school 

• Where should the traps be installed 

• When should the traps be installed 

• How frequent should the traps be 

installed 


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Questions 


• What is the procedure to be followed in 

installing the traps In servicing the 

traps What is the meaning of servicing 

the traps 

• Who will install and service the traps 


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Questions 


• Who will monitor and check the traps 

‣ Monitor 

• Empty tumbler 

• Missing tumbler/paddle 

‣ Check 

• If positive/negative 

• Is there a form to be filled-out 


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Questions 


• What index needs to be obtained 

• What formula is to be used 

• What is the meaning of the index 

obtained 

• Who will record and compute for the 

index 


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Questions 

• To whom should the data be submitted 

to Why 

• For how long will this ovitrapping be 

done 



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What’s inside 

• Vector 

• Surveillance 

• Prevention and Control 



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Vector 


• An arthropod (insects, mites, ticks) that 

are capable of: acquiring, supporting 

the development and transmitting a 

pathogenic agent (bacteria, viruses, 

parasites) from one host to another 

host 

Example: mosquito Aedes sp. 

transmitting dengue virus 


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Vector Control 

• suppression of a target population by 

using measures to alter the vector 

reproductive capacity or potential (Vector 

Genetics Course, 2010, India) 



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Dengue Vector Control 

• Application of various anti-DEN 

mosquito measures to alter the life 

cycle of the mosquito 



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• Specific Targets 

‣ Prevent and cut dengue transmission by: 

• Targeting larval stage through 

Trapping 

Larviciding 

Container management 

Environmental sanitation 


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• Targeting adult stage through 

Adulticiding 

» Space-spraying 

» Aerosol treatment 

Genetic manipulation of 

reproductive capacity of mosquito 


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• Prevention of man-mosquito contact 

curtains 

Screening of doors and windows 

Long pants 

Repellants 


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Integrated Vector Control 

• Combination of 2 or more vector 

control activities supplementary to 

each other towards reduction of 

dengue incidence 



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Integrated Vector Management 


• utilization of technical and managerial 

measures to bring about an effective 

degree of vector suppression 

to prevent and control 

transmission 


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Components of IVC 


• Vector biology/behavior 

• Surveillance tool (Ovitrap/OL Trap 

surveillance index) 

• Critical Threshold Density Index 

(effective degree of vector suppression 

[Ovitrap index] 

• Control Measures 

• Monitoring and evaluation 


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The Vector 



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Vector Biology 

Aedes aegypti 

Aedes albopictus 

General 

characteristics 

- primary vector 

- involve in cases of 

epidemics 

- urbanized areas 

- lives indoors 

- secondary vector 

- maintains the virus in 

the environment 

- rural areas 

- lives outdoors 


Breeding habitat 

- confined to artificial 

containers indoors 

- prefers to breed 

outdoor, in natural 

containers 

Resting habits 

- rests in cool, dark 

corners of the house 

- rests outdoors in 

clearings and 

vegetations 


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Morphology 

Aedes aegypti 

Aedes albopictus 

Size - 3-4 mm - same 

Color - dark brown to black - same 

Thorax 

- lyre-shaped white 

marks or scales 

- single white marks 


Abdomen 

- with white scales 

- with white and dark 

marks 

Legs - with white marks - same 


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Vector Characteristics 


• Biting Habits 

‣ “daybiters” with two peaks of biting time: 

• 1 to 2 hours after sunrise 

• 1 to 2 hours before sunset 

‣ only female mosquitoes bite because of the 

requirement of blood for oviposition 

‣ males do not bite but feed on plant juices 

and nectar of flowers 

‣ man is the preferred host but 

in his absence, lower 

vertebrates serve as substitute 


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Vector Characteristics 


• Flying Habit 

‣ do not fly great distances 

‣ farthest flight distance is within 200 to 400 

meters radius from their breeding places 

• Adults found around 50 meters from 

the breeding sources 


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Bionomics 


• at temperatures 40 o C, no 

developmental process takes place 

• females mates with male only once 

• Blood meal takes place after 

48 hours from emergence and 

after mating for egg 

production 


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Bionomics 


• oviposition takes place about 2 to 5 

days from blood engorgement 

• prefers dark-colored background for 

oviposition 

• lays egg 3 to 4 times in its lifetime 

‣ 60 to 100 eggs per batch 

• Survival potential: 20-30 days 


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Life Cycle (10-12 days) 

Adult 

-Maxillary pulps 

shorter than probosis 

-Wings uniformly 

grayish black 

-Body and legs are 

black with distinctive 

white patches 

throughout 

-Thorax has 

markings 

Eggs: 

- Black and oval in 

shape 

- Laid singly above 

water surfaces of 

containers 

- Without float 

- Viability: 6 months 

to 1 year due to 

the presence of 

chorion 


Pupa 

-Non-feeding stage 

-Breeding trumpet is 

long, slender with 

narrow opening 

1 - 2 days 

6 - 8 days 

2 - 3 days Larva: 

- Feeding stage 

- Breeds in clean and 

non-polluted water 

- Short and stout 

siphon with one pair 

of hair tuft 

- Rests at an angle to 

the water surface 


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Surveillance 



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Vector Surveillance 


• Collection and interpretation of data 

which can be used to guide mosquito 

vector control operations 

• Establish baseline 

• Presence or absence of vector 

‣ Species 

‣ Density 

‣ Changes 


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Dengue Surveillance Tool 


• Classical OVITRAP/LARVITRAP 

(black tumbler, paddle, water) 

• Modified OVITRAP is the OLTRAP 

(black container, paddle, 

water and organic 

larvicide) 

• 2 adults (females) 

emerging per day 

(Malaysian experience) 


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Difference between tools 

Ovitrap 

OL Trap 

Eggs on the paddle - Yes - Yes 

Live larva seen - Yes - No 

Action - Eggs trapped - Eggs trapped 

With organic larvicide 

Value-added 

- None 

- None 

- Yes 

- Additional attractant 

(kills larva) 


Risk - with white marks - same 

Benefit 

- Breeds Aedes, if 

uncollected (set and 

collect) 

- Breeds Aedes, if 

uncollected after 7 

days (set and collect) 

Index (CTDI) - Ovitrap index : 10% - OLTrap: 10% 


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Ovitrap Index 

Total Number of positive traps 

Total Number of traps planted 

X 100% 


If OI is >10%, the place is vulnerable to 

dengue transmission. 


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Critical Threshold Density Index 

(CTDI) 

• Actual target for the degree of vector 

suppression 

• Predictive value for the prevention of 

dengue transmission 



36

Remember: 


• A positive trap means there is at least 

one mosquito laying its eggs in the 

sampling site (surveillance site) 

• Aim is eliminate this one mosquito 

laying its eggs 


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What is DOST Mosquito Ovi/Larvicidal 

(OL) Trap System 

• Is a system used to control the population of the 

dengue carrying Aedes mosquitoes. 

• It has three important parts: a black container, a 

small strip of lawanit measuring 1” x 6.5” for 

mosquitoes to lay their eggs on, and pellets as 

larvicide. 

Tumbler 


•The OL-Trap’s ovicidal and larvicidal effect 

prevent the next generation of mosquitoes from 

reaching adulthood, thus curbing the Aedes 

mosquito population. 

Paddle 

Pellets 


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HOW THE OL-TRAP WORKS 

• The idea is to attract mosquitoes particularly the 

Aedes aegypti and albopictus (dengue carrier) to lay 

their eggs on the lawanit paddle. 

• The trap creates optimum conditions for this species 

to lay its eggs: stagnant, clean, clear water, dark 

area and damp rough surface. 



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• The eggs will either be trapped in the lawanit paddle 

or find its way into organic solution, where they are 

killed before transforming into adults. 

Eggs 


Larvae 


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Distribution of OL Trap 



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CLASSROOM 

1 OL Trap –indoor 

and 

1 OL Trap-outdoor 

CLASSROOM 


and 


CLASSROOM 


and 


CLASSROOM 


and 


SCHOOL 

CLASSROOM 


and 

1 OL Trap-outdoor

1 OL Trap indoor 

1 Tumbler (Black 

Container) 

1 sachet of pellet per week 

1 pc paddle per month 

1 OL Trap outdoor 

CLASSROOM 

1 Tumbler (Black 

Container) 

1 sachet of pellet per 

week 

1 pc paddle per month

Servicing the OL Trap 


• OVITRAPS are installed and serviced 

every seven days in locations where 

transmission of dengue is probable 

‣ nursery schools 

‣ pre-schools 

‣ elementary schools 

‣ Hospitals 

‣ community with confirmed dengue cases 

‣ Ovitrap Index = > 10% 


44

Before OL Trap Installation 

• Clean-up all possible breeding sites/containers found 

inside/outside the classrooms – DO SEARCH and DESTROY 


Artificial containers 

(man-made) 

1. Flower vases and pot plates 

2. Pails, water-storage jars, basins 

3. Discarded receptacles 

4. Choked roof gutters 

5. Gully Traps 

6. Unused toilet bowls and cisterns 

7. Aircon Tray and dish rack tray 

8. Concrete drains 

Natural containers 

1. Tree Holes, bamboo stumps 

2. Leaf axils, fallen leaves 

3. Ground Depressions 


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Where to set up the DOST OL-Trap 


A. Indoor: 

• Under the sink 

• Corner of the room 

• Under the cabinet 

• Under the bed 

• Inside the comfort room 

B. Outdoor (covered area): 

• Corner of the classroom 

• Near vegetation 

• Piles of woods/hollow 

blocks 

• Garden 


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Setting the OL Trap 

• Step 1 

‣ Fill the plastic tumbler with tap 

water up to the lined mark just 

above the DOST logo (~250 ml) 



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• Step 2 

‣ Pour one pack OL pellets 

into the plastic cup 

‣ Stir thoroughly to ensure 

pellets are dissolved 


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• Step 3 

‣ Place the lawanit stick in the 

solution with the rough 

surface facing up 



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• Step 4 

‣ Place 1 cup each inside 

and outside the classroom 

in a low-lying and dark area 

• If outside, protect from direct 

sunlight and rainfall 

• Take care not to spill the 

contents 

• Keep out of reach of children 

and animals 


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• Step 5 

‣ Collect trap and note for 

the following on the seventh (one 

week after installation (every 

Monday) day 

• Eggs on the paddle 

• Live larva/pupa 

• The presence of even one 

larvae indicates a positive trap 

‣ Record in the OL Trap 

Monitoring Sheet (3 copies) 


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• Step 6 

‣ Repeat steps 1-5 every 7 days 

• Set and collect the traps every Monday 

• Finalize report every Tuesday 

Note: If collection period falls on a holiday, please 

collect traps a day before 


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Cleaning the Trap 


• Vigorously brush-off into 

the solution eggs stuck 

into the lawanit creases 

• Kill the larva/eggs by 

pouring hot water into 

the black tumbler 

• Dispose contents 

properly by pouring 

contents on dry ground 


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Identifying a POSITIVE/NEGATIVE Trap 


Presence (+)/ absence (-) 

of eggs in the paddle 

Presence (+)/ absence (-) of larvae 

in the container/tumbler with water 


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An OL Trap is positive or negative if; 

Paddle Tumbler RESULT 

Positive (+) Positive (+) = POSITIVE (+) 

Positive (+) Negative (-) = POSITIVE (+) 


Negative (-) Positive (+) = POSITIVE (+) 

Negative (-) Negative (-) = NEGATIVE (-) 


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OL Trap Monitoring Sheet 


Click 

here 


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Filling Out of Monitoring Sheet 


Click 

Here 


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Prevention / Control 



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School Assemblies 



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School Dengue Brigade 



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Search and Destroy Activities 



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Brigada Iskwela 

(School Clean-ups) 



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Installation of Long-lasting 

Insecticide-treated Nets (LLINs) 



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Space-spraying Activities 



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“Dengue prevention and control 

rests primarily on the people who live 

in the houses where the problems 

occur and by the people who help 

create the mosquito larval habitats 


by their lifestyles.” 


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Setting the OL Trap - DepEd Naga City

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