Parasitic Pests

Parasitic pests are of great concern because of their spread of pathogens which lead to pathologies such as malaria, West Nile, heartworm, and Rocky Mountain Spotted Fever. Some of these pathologies are fatal in some cases. Descriptions of these pests and the control measures are described here.

Mosquitoes

There are 63 species of mosquitoes in Georgia and, of these, 10-12 species are known pests that measure about ⅖ inch long. Mosquitos are related to flies and are found in the insect order Diptera, which means "two wings," referring to the single pair of wings that these organisms use for flight.

Male mosquitoes feed on nectar, however, female mosquitoes of most species feed on blood which is needed for reproductive fitness. Blood is acquired through biting hosts, including humans and other animals. This is the need for pest control as mosquitos pass on diseases through their blood-feeding habits.

The female elephant mosquito (Toxorhynchites rutilus) doesn't feed on blood as do other female mosquitos, but prefers nectar. The Southern house mosquito (Culex quinquefasciatus) is the primary vector of West Nile Virus in Georgia. The prominent proboscis for feeding is seen in the region of the head in all of these images. The common malaria mosquito (Anopheles quadrimaculatus) is the primary vector or carrier of the pathogen that causes malaria.

Bed Bugs

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Bed bugs (Cimex lectularius) undergo incomplete metamorphosis and prefer bats and humans as hosts. These insects are ¼ inch long and flat, oval reddish-brown in appearance, and produce a weal at the site of the bite, which is an inflamed area with a red center. An infestation of this type of is pest indicated by the smell of fresh red raspberries.

Pest Control

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Besides blood, mosquitos require a water source for development. Therefore, control of this pest involves eliminating standing water sources, including in trash piles, storm drains, and catch basins.

Mosquito repellents are also available, which can be applied to the skin or clothing. Insecticides are applied to wide areas of land where mosquitoes live.

Lastly, insecticides target mosquito larva and adult populations.

Dusts and liquid formulations applied to cracks and crevices where bed bugs live are the usual control protocols for these parasites. Mattresses can be treated with sprays and should be dried before covering with sheets. Surfaces that will come into contact with humans cannot be treated against bed bugs.



Toxorhynchites rutilus

Mosquito species in Georgia fall into one of three subfamilies: Toxorhynchitinae, Anophelinae, or Culicinae.

Elephant mosquito (Toxorhynchites rutilus)—found in artificial containers; females don’t feed on blood, but these insects feed on carbo-rich foods, such as nectar; larval stage are predacious and inhibit other pest species, including other mosquitos. Eggs are laid singly on water surface.

  • Key word:  Autogeny is the production of eggs without blood.


Fleas

The cat flea, shown here, is similar but more widespread than the dog flea

Fleas, which measure nearly ⅑ inch long, are of concern because they transmit dog tapeworm and bite humans.  Cat fleas (Ctenocephalides felis) and dog fleas (Ctenocephalides canis) undergo complete metamorphosis and prefer pets as hosts for blood. Larva feed on dried blood and fecal matter from the adult fleas. Fleas are wingless.

Pest Control (cont'd)

Cultural controls of flea infestations involve frequent vacuuming and washing. Pesticides applied as surface and crack-and-crevice treatments, such as with insect growth regulators (IGR) are used to complement these cultural controls.

 A veterinarian or owner is responsible for the treatment of infected pet animals. Ultrasonic Pest Management Devices (UPMD) have been shown to be ineffective for flea control.

To eliminate tick infestations, known habitats should be sprayed monthly using spot treatments Pet animals that are infected with ticks should be seen by a veterinarian as the treatment of pets is beyond the purview of pest control services.

Lastly, mites can be controlled with mechanical, including vacuuming, washing, and chemicals called acaricides, such as permethrin.

The common malaria mosquito (Anopheles quadrimaculatus) is the primary vector or carrier of Plasmodium spp., which causes malaria. The prominent proboscis is seen in the head region.

Anopheline larvae are characterized by the absence of a respiratory siphon, and the presence of palmate hairs positioned dorsally on each side of segments IV-VI of the abdomen.  These larvae lie parallel to surface of water surface. Eggs are laid singly on water surface.

The Anopheles quadrimaculatus (common malaria mosquito)—vector of malaria by propagative-developmental transmission of Plasmodium spp, which infects hundreds of millions of people annually with nearly 1 million deaths; feeds on humans and other warm-blooded animals; females live 4-5 months through hibernation; fly about ½ mile.  Malaria is treated prophylactically (prevention strategy) and therapeutically (post-infection treatment).

Mites

The itch mite magnified 100x, light microscope, showing two pairs of legs, one set in the head position and one set in the hind position, attached to a spherical body.

Many mites are minuscule or microscopic and difficult to see with the unaided eye. One such species is the itch mite (Sarcoptes scabiei), which causes scabies. Scabies, which is transmitted through contact with infected individuals, causes intense itching and inflammation but this condition is not fatal.

Culex spp.

Culicinae larvae always have a respiratory siphon and these types of mosquitoes do not have palmate hairs; larvae lie 45° angle to water.  Eggs are laid in rafts for this group.

Southern house mosquito (Culex quinquefasciatus )—primary vector of WNV with Culex resturans in Georgia. West Nile was first noted within the US in 1998; causes West Nile fever in humans and horses, which are flu-like symptoms that affect the central nervous system (CNS).

Black-tailed mosquito (Culiseta melanura —transmits Eastern equine encephalitis (EEE; Triple E) between birds; doesn’t typically bite humans.

The presence of virus particles in blood is called viremia.

Ticks

Ticks are mites are not considered insects, but are arachnids, and are more related to arachnids, such as spiders and scorpions than to insects.

The tick measures ¼ inch when unfed, and just over ⅓ inch after a blood meal. The deer tick (Ixodes scapularis) spreads Lyme disease, which is more common in Georgia than Rocky Mountain spotted fever (RMSF), which is spread by the brown dog tick (Rhipicephalus sanguineus). The tick undergoes four life stages: egg, six-legged larva, eight-legged nymph, and adult and prefers dogs over humans for blood meals.

From L-R: The deer tick can be distinguished from the brown dog tick by the two-tone reddish-brown and dark brown colors on its dorsal surface. The body of the brown dog tick is more even colored.

According to the Centers for Disease Control, the brown dog tick is home to the whole contiguous United States.

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