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Evidence of an 'invitation' effect in feeding sylvatic Stegomyia albopicta from Cambodia.

Charlwood JD, Tomás EV, Kelly-Hope L, Briët OJ - Parasit Vectors (2014)

Bottom Line: Orientation of haematophagous insects towards a potential host is largely mediated by kairomones that, in some groups or species may include chemicals produced during feeding by the insects themselves, the so called 'invitation' effect.This preference did not vary with collector or pyrethroid.The 'invitation' effect may be due to a semio-chemical produced early in the feeding process.

View Article: PubMed Central - HTML - PubMed

Affiliation: Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK. jdcharlwood@gmail.com.

ABSTRACT

Background: Orientation of haematophagous insects towards a potential host is largely mediated by kairomones that, in some groups or species may include chemicals produced during feeding by the insects themselves, the so called 'invitation' effect.

Methods: The 'invitation' effect in blood-feeding diurnally active Stegomyia albopicta was investigated over 33 days in secondary forest in Mondolkiri Province, Cambodia. Two human volunteers sitting inside a shelter collected mosquitoes and noted where and when they landed. A 10% emanator of a synthetic pyrethroid with high vapour action was in use on alternate days.

Results: Overall, 2726 mosquitoes were collected, 1654 of which had the landing site recorded. The heads of the volunteers were the locations with the highest density of landings per surface area whilst the knees and elbows accounted for most of the landings received on the arms and legs. Landings recorded within three minutes of each other on a collector were about 2.5 times more likely to be on the same body part than on a random body part, weighted for landing site preference. This preference did not vary with collector or pyrethroid.

Conclusions: The 'invitation' effect may be due to a semio-chemical produced early in the feeding process. Incorporation of such a chemical into traps designed to control this important vector of dengue and chikungunya viruses might potentially improve their attractiveness.

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Related in: MedlinePlus

Landing activity of St. albopicta between 08:30 and 17:30 in Ou Chrar woods, Mondolkiri Province, Cambodia May – June 2013. Vertical lines indicate 95% confidence intervals. Red: With a pyrethroid emanator Blue: Without emanator
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Figure 4: Landing activity of St. albopicta between 08:30 and 17:30 in Ou Chrar woods, Mondolkiri Province, Cambodia May – June 2013. Vertical lines indicate 95% confidence intervals. Red: With a pyrethroid emanator Blue: Without emanator

Mentions: Numbers of St. albopicta biting increased to a maximum between 15:30 and 16:30 (Figure 4). The mean temperature recorded at 16:00 (the time of peak biting) was 32.6°C (minimum 32°C, maximum 36°C) and the mean relative humidity was 75.4% (minimum 60%, maximum 87%). Rain fell on 29 of the 40 days between the 21st of April and the 30th of May. On 11 of these days, more than 20 mm of rain was recorded. Over the entire study period, a total of 353.7 mm of rain was recorded in the village. Most of the rain fell during the night or late evening. However, on four days, heavy rain fell during the period between 14:00 and 17:00. This significantly reduced biting (p value <0.0001) according to the exact rate ratio test and assuming Poisson counts; thus only 53.4% (95% C.I. = 44.8 – 63.0) of the expected numbers were collected on days when heavy rain fell during the period between 14:00 and 17:00 as compared to when there was no heavy rain. Airflow was always low: with the door open, it was generally less than 0.25 m per second, while closing the shelter doors reduced airflow by approximately 50%.


Evidence of an 'invitation' effect in feeding sylvatic Stegomyia albopicta from Cambodia.

Charlwood JD, Tomás EV, Kelly-Hope L, Briët OJ - Parasit Vectors (2014)

Landing activity of St. albopicta between 08:30 and 17:30 in Ou Chrar woods, Mondolkiri Province, Cambodia May – June 2013. Vertical lines indicate 95% confidence intervals. Red: With a pyrethroid emanator Blue: Without emanator
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4230241&req=5

Figure 4: Landing activity of St. albopicta between 08:30 and 17:30 in Ou Chrar woods, Mondolkiri Province, Cambodia May – June 2013. Vertical lines indicate 95% confidence intervals. Red: With a pyrethroid emanator Blue: Without emanator
Mentions: Numbers of St. albopicta biting increased to a maximum between 15:30 and 16:30 (Figure 4). The mean temperature recorded at 16:00 (the time of peak biting) was 32.6°C (minimum 32°C, maximum 36°C) and the mean relative humidity was 75.4% (minimum 60%, maximum 87%). Rain fell on 29 of the 40 days between the 21st of April and the 30th of May. On 11 of these days, more than 20 mm of rain was recorded. Over the entire study period, a total of 353.7 mm of rain was recorded in the village. Most of the rain fell during the night or late evening. However, on four days, heavy rain fell during the period between 14:00 and 17:00. This significantly reduced biting (p value <0.0001) according to the exact rate ratio test and assuming Poisson counts; thus only 53.4% (95% C.I. = 44.8 – 63.0) of the expected numbers were collected on days when heavy rain fell during the period between 14:00 and 17:00 as compared to when there was no heavy rain. Airflow was always low: with the door open, it was generally less than 0.25 m per second, while closing the shelter doors reduced airflow by approximately 50%.

Bottom Line: Orientation of haematophagous insects towards a potential host is largely mediated by kairomones that, in some groups or species may include chemicals produced during feeding by the insects themselves, the so called 'invitation' effect.This preference did not vary with collector or pyrethroid.The 'invitation' effect may be due to a semio-chemical produced early in the feeding process.

View Article: PubMed Central - HTML - PubMed

Affiliation: Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK. jdcharlwood@gmail.com.

ABSTRACT

Background: Orientation of haematophagous insects towards a potential host is largely mediated by kairomones that, in some groups or species may include chemicals produced during feeding by the insects themselves, the so called 'invitation' effect.

Methods: The 'invitation' effect in blood-feeding diurnally active Stegomyia albopicta was investigated over 33 days in secondary forest in Mondolkiri Province, Cambodia. Two human volunteers sitting inside a shelter collected mosquitoes and noted where and when they landed. A 10% emanator of a synthetic pyrethroid with high vapour action was in use on alternate days.

Results: Overall, 2726 mosquitoes were collected, 1654 of which had the landing site recorded. The heads of the volunteers were the locations with the highest density of landings per surface area whilst the knees and elbows accounted for most of the landings received on the arms and legs. Landings recorded within three minutes of each other on a collector were about 2.5 times more likely to be on the same body part than on a random body part, weighted for landing site preference. This preference did not vary with collector or pyrethroid.

Conclusions: The 'invitation' effect may be due to a semio-chemical produced early in the feeding process. Incorporation of such a chemical into traps designed to control this important vector of dengue and chikungunya viruses might potentially improve their attractiveness.

Show MeSH
Related in: MedlinePlus