Chapter 13

Chapter 13 BIOLOGY AND CONTROL OF INSECT PESTS

DR. D. T. CAPPUCCI, JR.

13.1 Objective:

To review arthropods of medical and veterinary importance.

13.2 General Information about Arthropods

Various arthropods can infest people and animals, with subsequent discomfort and illness: dermatitis, disease, and death. However, the greatest dangers to human and animal populations lie not in the arthropod infestations themselves, but in the diseases for which the arthropods may serve as vectors, such as encephalitides, hemorrhagic fevers, rickettsioses, nematode parasitisms, plague, tularemia, and dysentery. The following remarks will address the biology, animal and public health importance, and control of various arthropods. See figure 1 for pictorial review of arthropods of animal and public health importance.

13.3 Biology, Importance and Control

13.3.1 Arachnids

They are not insects

1. Spiders

Black Widow Spider (Latrodectus mactans)

neurotoxin - CNS signs

hour-glass marking on abdomen

control by environmental measures and destruction of pests

Brown Recluse Spider (Loxosceles reclusa)

necrotoxin - loxoscelism - dermal necrosis, renal failure, and

shock

fiddle-shaped marking on cephalothorax

control by environmental measures and destruction of pests

2. Scorpions

Pest in southwestern USA

poisonous sting

problem to humans and pets

control by environmental measures and destruction of pests

3. Mites

Transmit scrub typhus and cause dermatitis

Sarcoptes spp. and Cheyletiella spp. in USA - dermatitis human infestations from pets

mites in Orient transmit scrub typhus-a public health problem

control with acaricides, sanitation and improved husbandry practices

4. Hard-back Ticks

Transmit Rocky Mountain spotted fever, Q-fever, tularemia, Colorado tick fever, Lyme disease, and cause dermatitis and envenomization

control - Hosts need to be protected from toxicosis, diseases, dermatitis, paralysis, and death. Also to prevent spread of ticks and their diseases. Control achieved using cultural, biological, and chemical methods. Some vaccines are available using (tick) antigens. Control strategies entail use of acaricides for tick eradication, animal quarantine, and other combinations thereof. Repellents are helpful.

5. Soft-back Ticks

Transmit relapsing fever, African swine fever, epizootic bovine abortion, fowl spirochetosis, and cause tick paralysis and dermatitis

control - see hard-back ticks

13.3.2 Cockroaches

Presence associated with filth and unsanitary practices
Transmit Salmonella spp. and cause dysentery
Newer field studies have shown that earlier documentation for origins of roaches were erroneous
control with chemicals, such as residual and space sprays, fogs, etc. Boric acid powder is also used for control. Bait traps have been used with variable success.
1. German cockroach (Blattella germanica)

2. Oriental cockroach (Blatta orientalis)

3. Brown-banded cockroach (Supella supellectilium)

4. Australian cockroach (Periplaneta australasiae)

5. American cockroach (Periplaneta americana)

6. Others - See Figure 2

13.3.3 True bugs

1. Bed bugs

Dermatitis and loss of sleep found in unsanitary quarters control by clean-up of the housing environment

2. Assassin bugs

Chagas’ disease and Trypanosoma cruzi

spread to humans by fecal material of triatoma bugs in bite wounds and contaminated blood supplies control by clean- up of the environment, especially living quarters. Repellents are helpful.

13.3.4 Fleas

1. Human, dog, and cat fleas - usually species specific although human infestation occurs from contact with pets and vice versa
2. Flea allergy and dermatitis - no easy solution, desensitization not always successful
3. Plague and Yersinia pestis - urban and rural forms
a worldwide public health problem, which involves international quarantine when identified and a threat to foreign countries
4. Endemic typhus - a public health problem associated with rodent-flea infestation
5. Dipylidium caninum and the dog flea (Ctenocephalides canis) - an animal health problem but not a public health problem
6. Control - one must understand the flea’s life-cycle in order to achieve control of the insect pest can survive up to 7 months without a bloodmeal can complete their entire life-cycle in just 3 weeks are great jumpers and resistant to many insecticides

chemical control includes the use of synergized pyrethrins, synthetic pyrethroids, carbamates, organophosphates, insect regulators such as methoprene, and natural herbal remedies fleas collars and ultrasound devices have been used on pets clean-up of the environment, especially living quarters of humans and pets is necessary part of control

13.3.5 Lice

1. Biting lice

(Order: Mallophaga) and sucking lice (Order: Anoplura) biting lice infest both birds and mammals sucking lice infest only mammals

2. Epidemic typhus

Associated with wars and major disasters

3. Dermatitis and disease

Pediculosis lice ova called nits, mature lice called cooties or crabs .lice found on head, body, and pubic areas

4. Control

Use of external parasiticides including, medicated soaps and shampoos, as well as dips and sprays. In previous years toxic chemicals such as DDT and other chlorinated hydrocarbons were used directly on humans and animals.

13.3.6 Flies, Midges, and Gnats

1. Nonbiting and biting flies
2. Role of flies in the transmission of diseases
3. Black flies, biting gnats, blowflies, buffalo flies, face flies, bottle flies, primary and secondary screwworms, horn flies, horse flies, deer flies, house flies, little house flies, garbage or dump flies, stable flies, false stable flies, black soldier flies, moth flies, and others. See Figure 3.
4. Transmit the nematode parasitism of onchocerciasis, equine infectious anemia, tularemia, anthrax, anaplasmosis, yaws, typhoid fever, cholera, conjunctivitis, African sleeping sickness, bluetongue and dysenteries. Cause myiases (cutaneous and other forms).
5. Control - use of repellents such as DEET and dimethyl phthalate, electrical grids, insecticide resin strips, fly baits, residual and space sprays, mists, fogs, larvicides on fly breeding areas, physical destruction, and environmental sanitary measures.Genetic resistance to chemical agents is on the rise, alternatives for fly control are needed

13.3.7 Mosquitoes

1. Anopheline and Culicine mosquitoes (Anopheles spp., Culex spp., and Aedes spp.) as vectors of medical and veterinary importance. See Figure 4 for comparisons and contrasts of eggs, larvae, pupae, and adults.
2. Transmit diseases of international importance such as malaria, yellow fever, dengue, elephantiasis, and encephalitis in humans. Also transmit, Rift Valley fever, encephalitis, and heartworm disease in animals.
3. Discomfort and dermatitis
4. Historical and contemporary control measures
5. Control - with larvicides, repellents, fogs, mists, residual and space sprays .Genetic resistance to chemical agents is on the rise, alternatives for mosquito control are needed

13.3.8 Ants, bees, hornets and wasps

1. Nuisance pests
2. Bites and stings
3. Allergies and hypersensitivities
4. Control measures, including concerns about foreign pests Control with repellents, fogs, mists, residual and space sprays for bees, hornets, and wasps. Use of knock-down versus residual chemicals in the environment is controversial for bees, hornets, and wasps. Genetic resistance of ants to chemical insecticides is becoming more commonplace. Residual chemicals and sprays are most widely used for the control of ants, although environmental sanitation is necessary. African bees and fire ants are threats to animal and public health.
5. Issues of consideration in selecting insecticides: cost, active chemical ingredients, target insect, efficacy, safety, regulatory status of product, convenience of use, and aesthetic acceptability.

V. References

Beaver, P. C. Jung, R. C. Animal Agents and Vectors of Human Disease, 5th edition. Lea & Febiger, Philadelphia, 1985.
Beaver, P. C. Jung, R. C. and Cupp, E. W. Clinical Parasitology, 9th edition. Lea & Febiger, Philadelphia, 1984.

Ehlers, V. M. and Steel, E. W. Municipal and Rural Sanitation, 6th edition. McGraw-Hill Book Company, New York, 1965.

Fraser, C. M. (ed.) The Merck Veterinary Manual, 7th ed. Merck and Company, Inc., Rahway, NJ, 1991.

Schwabe, C. W. Veterinary Medicine and Human Health, 3rd edition. Williams & Wilkins, Baltimore, 1984.

VI. Questions

1. Both people and animals are known to be allergic to bee stings. How would you handle a case of hypersensitivity to a bee sting involving a five-year-old Labrador Retriever that came into your clinic in shock?
2. If a client asks you about Lyme disease, what would you tell him/her regarding treatment, prevention and control of the disease in animals and humans?

3. Differentiate between anopheline and culicine mosquitoes relative to morphological characteristics.

4. Be able to identify common domestic flies using a pictorial key.

5. Be able to identify common adult cockroaches using a pictorial key.

6. How would you control/prevent cockroach infestation in a house or apartment?

7. How would you control screwworms in livestock and poultry?

8. Discuss the United States Department of Agriculture screwworm eradication program that has been in place in Central America and Mexico.

9. Discuss the uses of pesticides and insecticides from a standpoint of animal and public health and safety, including storage, usage, and disposal suggestions.

10. Name at least 10 diseases or disease conditions involving insect and arthropod pests of medical and veterinary importance.