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Case Study 2

Case study: Singapore

Vector: Mosquitoes

Customer: Singapore Defence Ministry

The Challenge

Singapore's climate is characterized by uniform temperature and pressure, high humidity and abundant rainfall is ideal for the breeding of the Aedes mosquito. Aedes consists of about 500 species, of which the Aedes aegypti and Aedes albopictus are two main species which transmit mosquito-borne encephalitis, malaria, dengue fever, dengue hemorrhagic fever, and most recently chikungunya to humans.

The warm and humid temperature between 30°C and 33°C has shortened the life cycle of the mosquitoes and therefore the number of generations produced per year by the mosquito population has increased. Rainfall is almost an everyday phenomenon, even during the non-monsoon period and it has provided abundant breeding spots for Aedes mosquitoes to multiply in both urban, suburban and rural areas.

Active ingredients used in many larvicidal products are widely used in the pest control industry. This routine usage with the short mosquito life cycle is known to create resistance in the target population, and lost effectiveness.

Rentokil Solution

Rentokil has developed a tailored vector control strategy, which includes an extensive field control program targeted at the various stage of the mosquito life cycle, as well as an state of the art monitoring program with GPS based reporting and carrier analysis.

In order to overcome the resistance issue at the larvae stage, we conducted extensive field trials to evaluate the effectiveness of specific products in the local environment. Following this trial and error process, we have selected an effective microbial larvicides which is not harmful for humans, nor the environment. Importantly, other living organism from the same ecosystem such as butterflies, dragonflies and ants are not affected.

Different monitoring tools are used to determine the locations and seasons that mosquitoes use specific aquatic habitats and, when specimens are identified and counted, the information can be used to determine species composition and population densities. The monitoring devices are mapped using global positioning system (GPS).

Mosquitoes’ larvae and adults density and composition are recorded and underlying data is analysed. Analyses and trends are reported real time. In addition adult mosquitoes are analyzed for pathogenic microorganism they may carry. It is the combination of composition and population reporting, together with the analyses for the presence and penetration of vector borne diseases in the Aedes musquitos, that allows proper risk assessment and steers corrective measures.

Outcome

The selected microbial larvicide is very effective against mosquito larvae. Mortality of mosquito larvae is usually observed within 2-24 hours. The microbial activity is very species specific where it is known to effectively control the mosquito larvae from the genera of Aedes, Culex, Anopheles and Mansonia. The total mosquito count below has shown a decrease of 93.5 % in mosquito count 5 weeks after the initial treatment.