Wendell Arnett from Bayer Environmental Science shares a top-line view of mosquito biology and the current control methods available.
Nothing quite says summer’s here more than balmy evening barbecues and drinks on the patio. And nothing ruins these nights quite like the incessant buzz of incoming mosquitoes ready to attack. Fielding questions from customers about mosquitoes and what can be done about them is common at this time of year, so it’s worth brushing up on the basics.
There are more than 3500 species of mosquitoes worldwide, with more than 300 of these found in Australia. Belonging to the family of flies called Culicidae, these blood-sucking pests can be distinguished by their protruding heads, compound eyes and long antennae, which are around three times longer than the head itself. Male mosquitoes tend to have antennae which are more hairy and bushy than those of the female mosquitoes.
Mosquitoes have four life stages: egg, larva, pupa (pictured above, below the water line) and adult. Their immature stage is purely aquatic while their adult stage is terrestrial, and their entire life cycle from egg to adult takes approximately 8-10 days. During the life cycle the male and female will feed on nectar and plant fluids. On average, a female mosquito will live for between two to three weeks, while the male’s lifespan is much shorter. Mosquitoes mate within 48 hours and the female mosquito only mates once in her lifetime, being able to store sperm in sacs within her body and fertilise subsequent batches herself. Females also need a protein-rich blood meal for her egg development and will use her sensory organs to detect body smells, carbon dioxide, and emanating warmth and moisture, to distinguish the host.
Mosquitoes can be found in every type of climatic region of the world, from the arctic to the tropics. Depending on the species, they will breed in water – be it heavily polluted or clean – including small collections of water in tin cans, old car tyres, pools and streams.
Apart from their nuisance value, mosquitoes represent a significant health concern, spreading a range of diseases such as dengue fever and ross river fever. The introduction of mosquito species and disease from overseas, and their spread within Australia, have been aided by human movement and trade, and will be influenced into the future through a changing climate.
Adult mosquitoes can be controlled indoors by using an aerosol while their bite can be minimised with repellents, treated bed nets or mosquito coils.
Since mosquitoes live in and around water, removing receptacles containing water, ensuring drainage channels run freely and draining standing-water from building sites, earthworks etc, eliminates potential breeding sites and can help in controlling numbers outdoors.
Space sprays, like Bayer’s Aqua K-Othrine, are designed to kill adult mosquitoes outdoors. Even though Aqua K-Othrine contains deltamethrin – known for its long lasting residual performance – it is designed as a space spray application to control mosquitoes on the wing. As such it is best applied during times of optimal activity, which is generally early evening to capture most species, but may need to be varied depending on the species present. The unique EW formulation with built-in FFAST anti-evaporant technology (Film Forming Aqueous Spray Technology), causes the water based droplets to behave more like oil droplets, ensuring a longer hang time after spraying and therefore a prolonged control period. As per label instructions, spraying under low wind conditions is required to deliver optimal performance and avoid unwanted spray drift. Depending on the nature of the problem, a regular spray program may be required.
Although designed as a high performance mosquito product with a high level of safety – it’s on the list of WHO pre-qualified vector control products – it is suitable for controlling a wide range of pests including flies, cockroaches, spiders and stored product pests. With its low rates of application, dilution with water and non-flammable attributes, Aqua K-Othrine is a flexible option for misting, cold or thermal fogging requirements.
Wendell Arnett, Territory Business Development Manager, Bayer Environmental Science