Veterinary Entomology and Protozoology Lecture 3-1 PDF

VPara161 VETERINARY ENTOMOLOGY AND PROTOZOOLOGY james vincent c. dizon, dvm V PARA 161 3. ORDER HEMIPTERA Veterinary Entomology and Protozoology ORDER HEMIPTERA (TRUE BUGS) hemipteran insects The Order Hemiptera has 80,000 species of...

VPara161 VETERINARY ENTOMOLOGY AND PROTOZOOLOGY james vincent c. dizon, dvm V PARA 161 3. ORDER HEMIPTERA Veterinary Entomology and Protozoology ORDER HEMIPTERA (TRUE BUGS) hemipteran insects The Order Hemiptera has 80,000 species of insects under it. This includes aphids, cicadas, stinkbugs, bedbugs and assassin bugs. The words hemi means 'half' + and pteron means 'wing'. Their forewings have a leathery basal part and a membranous apical portion. ORDER HEMIPTERA (TRUE BUGS) hemipteran insects In this class, we will mainly focus on two Families under the Order Hemiptera: Family Cimicidae - bed bugs Family Reduviidae - assassin bugs, cone-nosed bugs, kissing bugs ORDER HEMIPTERA (TRUE BUGS) hemipteran insects Some characteristics of Hemipteran insects: Their bodies are dorso-ventrally flattened. They may feed on plants, but some can kill insects and absorb their fluids. Development is incomplete metamorphosis. Nymphs! V PARA 161 3.1 ORDER HEMIPTERA bed bugs ORDER HEMIPTERA (TRUE BUGS) family cimicidae Also called bed bugs. They are small, reddish-brown, wingless insects that are an obligate occasional ectoparasite. This bug infests people, other mammals, especially bats, and birds around the world. ORDER HEMIPTERA (TRUE BUGS) family cimicidae Bedbugs are nocturnal, and are excellent at hiding in dark, soft places and crevices. This makes the mattress an ideal spot for them to settle, hence their name. The risk of running into bedbugs is higher if you spend time in places where guests come and go often — such as hotels, hospitals or shelters. ORDER HEMIPTERA (TRUE BUGS) family cimicidae Adult bed bugs measure 5–7 mm when unfed, with females being slightly larger than males. They are generally red–brown in color, although they appear darker following a blood meal. ORDER HEMIPTERA (TRUE BUGS) family cimicidae Some species in references: Cimex lectularius Cimex hemipterus C. lectularius has broader prothorax compared with C. hemipterus. C. hemipterus is longer than C. lectularius. ORDER HEMIPTERA (TRUE BUGS) family cimicidae Life Cycle of Bed Bugs Bed bug eggs are laid in cracks and crevices and hatch after 4–12 days. The nymphs will then consume a blood meal and then molt after feeding. They will molt 5 times, with intervals of 3-10 days, each requiring a blood meal. maximum: 50 days ORDER HEMIPTERA (TRUE BUGS) family cimicidae Life Cycle of Bed Bugs These bugs have an unusual way of mating. The process involves the male stabbing the female with its specialized reproductive organ anywhere in the abdomen. This process is called traumatic insemination. Constant mating may hurt the females. ORDER HEMIPTERA (TRUE BUGS) family cimicidae Life Cycle of Bed Bugs The spermalege (organ of Berlese) has been found in female bed bugs that appears to have evolved to mitigate the effects of traumatic insemination. The spermalege is visible externally, giving the male a target through which to impale the female. Found on the fourth abdominal sternum. ORDER HEMIPTERA (TRUE BUGS) family cimicidae Life Cycle of Bed Bugs Once the male gametes are inside the female's body cavity, they travel to the reproductive parts, meet the eggs, and fertilize them. The male seminal fluid contains antimicrobial properties, ensuring that no pathogens get introduced during the mating. ORDER HEMIPTERA Bed Bugs Life Cycle ORDER HEMIPTERA (TRUE BUGS) family cimicidae Pathogenic Effects of Bed Bugs Although bed bugs have been suspected in the transmission of many disease organisms, in most cases conclusive evidence is lacking, or experimental data have demonstrated that bed bugs are incompetent vectors. ORDER HEMIPTERA (TRUE BUGS) family cimicidae Pathogenic Effects of Bed Bugs The primary concern is the disturbance caused by nuisance biting. The bite causes irritation and swelling. Heavy infestations in poultry houses may result in chronic blood loss and mortality in young birds. ORDER HEMIPTERA (TRUE BUGS) family cimicidae Control of Bed Bugs Control is best accomplished by thoroughly cleaning the houses, reducing hiding places for the bedbugs, using heat treatments, and/or fumigating the houses. Animals may be treated with pour‐on formulations of pyrethroid insecticide to repel or kill host‐seeking bugs. V PARA 161 3.2 ORDER HEMIPTERA assassin bugs ORDER HEMIPTERA (TRUE BUGS) family reduviidae Also called assassin bugs, kissing bugs, or cone-nosed bugs. Most assassin bugs are predators of crop pests, but a few are blood-sucking. eat anything thye could acapture They are usually generalists, they may prey on aphids, leafhoppers and insect beetle eggs and larvae. ORDER HEMIPTERA (TRUE BUGS) family reduviidae As their name suggests, they are capable of "assassinating" other insects. They have a curved, dagger-like mouthpart which is used to kill prey. An assassin bug will spear its victim, inject digestive juices, and then suck on the prey to feed. ORDER HEMIPTERA (TRUE BUGS) family reduviidae Also, as their name suggests, they are capable of stealth. They can bite painlessly enough that when they feed on a sleeping host, it does not wake them up. nocturnal Like bed bugs, they hide during the day and attack when the host is sleeping at night. ORDER HEMIPTERA (TRUE BUGS) family reduviidae Examples of assassin bugs include insects under the Genera Triatoma, Panstrongylus and Rhodnius. Some species of triatomine bug live in and near human dwellings and poultry houses where they hide in cracks and crevices in the structure. During the night, they emerge to search for warm‐blooded hosts. ORDER HEMIPTERA (TRUE BUGS) family reduviidae Life Cycle of Assassin Bugs Assassin bug females deposit brown, cylindrical eggs in cracks on the ground, on leaves and stems. Immature nymphs hatch from these eggs within 1-4 weeks and are wingless. They molt 5 times, with the last instar developing into a winged adult in about 2 months. ORDER HEMIPTERA (TRUE BUGS) family reduviidae Pathogenic Effects of Assassin Bugs When these bugs feel threatened, they can deliver a painful jab, and will also inject venom or digestive juices. The wounds created are usually seen as erythematous papules or wheals. Pruritis may be intense. ORDER HEMIPTERA (TRUE BUGS) family reduviidae Pathogenic Effects of Assassin Bugs Heavy infestations in poultry houses may result in chronic blood loss and mortality in young birds. Infected dogs provide a reservoir of infection for the vector and thus human infection (for Chagas diseases, see next slide). ORDER HEMIPTERA (TRUE BUGS) family reduviidae Pathogenic Effects of Assassin Bugs Triatomines are important vectors of the protozoan Trypanosoma cruzi. This causes Chagas’ disease in humans and a disease of similar pathology in dogs. As it feeds, the bug defecates and the parasite is transmitted in the feces which is rubbed into the feeding wound or into the eyes or the mouth. ORDER HEMIPTERA (TRUE BUGS) family reduviidae Control of Assassin Bugs Vector control methods include applying insecticides to eliminate kissing bugs. Attraction of assassin bugs to houses can be decreased by turning off outdoor lighting. V PARA 161 END. Clean your beds!!