Fleas are cosmopolitan ectoparasites with a large variety of hosts. For companion animals and humans, the cat flea Ctenocephalides felis and the dog flea Ctenocephalides canis represent the most important species worldwide. Apart from causing flea allergy dermatitis (FAD), the ability of fleas to function as vectors for disease pathogens, such as Rickettsia & Bartonella spp. bacteria, Dipylidium caninum (dog tape worm) and some viral pathogens is gaining attention. Consequently flea control with highly efficient ectoparasiticides supports prevention of the direct effects of flea infestation on the pet and reduces the risk of transmission of flea-borne diseases to both pets and humans.
Anatomy of fleas…
Fleas are small (1/16 to 1/8-inch long), agile, usually dark coloured, wingless insects with tube-like mouth-parts adapted to feeding on the blood of their hosts. Their legs are long, the hind pair well adapted for jumping: a flea can jump vertically up to 7 inches (18 cm) and horizontally up to 13 inches (33 cm). This is around 200 times their own body length, making them one of the best jumpers of all known animals (relative to body size), second only to the froghopper.
Flea control depends on their life cycle…
In order to understand how and why treatment options work, one must first understand the flea’s life cycle, since the various modern treatment and prevention products work on different parts of this life cycle. The flea developmental cycle can be completed in as little as 14 days or last up to 140 days, depending mainly on temperature and humidity.
Life cycle of fleas…
There are several stages to its life cycle: egg, larva or caterpillar, pupa or cocoon, and adult. The length of time it takes to complete this cycle varies depending upon the environmental conditions such as temperature, humidity and the availability of a nourishing host. Yes… the various flea stages are quite resistant to freezing temperatures. The flea’s host is a warm-blooded animal such as a dog or cat (or even humans!). The adult female flea typically lives for several weeks on the pet. During this time period, she will suck the animal’s blood two to three times and lay twenty to thirty eggs each day. She may lay several hundred eggs over her life span. These eggs fall off of the pet into the yard, bedding, carpet, and wherever else the animal spends time.
These eggs then proceed to develop where they have landed. Since they are about 1/12th the size of the adult, they can even develop in small cracks in the floor and between crevices in carpeting. The egg then hatches into larvae. These tiny worm-like larvae live among the carpet fibers, in cracks of the floor, and outside in the environment. They feed on organic matter, skin scales, and even the blood-rich adult flea faeces. Larvae can ingest tapeworm eggs which develop into adult in the adult fleas, which then becomes the carrier for tapeworm transfer to dogs if ingested.
The larvae grow, molt twice and then form a cocoon and pupate, waiting for the right time to hatch into an adult. These pupae are very resilient and are protected by their cocoon. Pupae can survive quite a long time, waiting until environmental conditions and host availability are just right. Then they emerge from their cocoons when they detect heat, vibrations and exhaled carbon dioxide, all of which indicate that a host is nearby. The newly emerged adult flea can jump onto a nearby host immediately. Under optimal conditions, the flea can complete its entire life cycle in just fourteen days.
(Dr Mandar Deshpande, Business Manager & Dr Vishal Surve, Product Manager, Companion Animal Products, Bayer Pharmaceuticals Pvt Ltd).