Chapter 11 Flashcards
Cockroaches
Ants
Cockroaches (Blattaria)
Ants (Hymenoptera)
What is the oldest insect?
Cockroaches are among the oldest and most primitive
of insects.
* Earlier studies had concluded that they evolved about
350 million years ago (Mya) during the Silurian Period,
diverging together with the mantids from an ancestral
stock that also gave rise to termites (Boudreaux, 1979).
what are the most important medically cockroaches?
The most important medically are Blattella germanica
(the German cockroach), Blatta orientalis (the oriental
cockroach), Periplaneta Americana (the American
cockroach), P. australasiae (the Australian cockroach)
and Supella longipalpa (the brown-banded cockroach)
* They have an almost worldwide distribution
* Cockroaches aid in the mechanical transmission of
various pathogenic viruses, bacteria and protozoans
Cockroaches (Blattaria) - Morphologies
The more common household pest species are chestnut
brown or black, 10–50 mm long, flattened dorsoventrally,
and have a smooth, shiny and tough integument.
* The head is small and sometimes almost hidden by the
large, rounded pronotum. Apair of long and prominent
filiform antennae arise from the front of the head between
the eyes
* Cockroach mouth parts are developed for chewing, gnawing
and scraping; they cannot suck blood.
* Both sexes have two pairs of wings
- The cockroach fore-wings, called tegmina, are thick
and leathery. They are not used in flight but are
protective covers for the membranous hind-wings,
which when not in use are folded shut, fan-like,
over the body - Although the hindwings are used for flying,
cockroaches rarely fly. The well-developed legs are
covered with prominent small spines and bristles;
the five-segmented tarsi end in a pair of claws
Cockroaches (Blattaria) – Life Cycle
- Cockroaches have a hemimetabolous life cycle.
Nymphs hatch from eggs after about 1–3 months
There are commonly between five and seven nymphal
stages but there may be as many as 13 - Duration of the nymphal stage varies according to
temperature, abundance of food and species. It commonly
lasts 2–3 months in Blattella germanica, 12–15 in Blatta
orientalis, and 10–14 in Periplaneta americana, but
occasionally up to 23 months - Cockroaches spread very rapidly from infested houses to
adjoining ones. They often gain entry by climbing up water
pipes and waste pipes. They are also spread as oothecae,
nymphs and adults in furniture and other belongings
where do cockroaches live?
Cockroaches like warmth, and in temperate countries they often
hide behind radiators and hot-water pipes during the day
* In warm countries they are found in almost any dark place, such
as cesspits, septic tanks, sewers, refuse tips, dustbins, cupboards,
underneath chairs, tables, sinks, baths and beds, behind
refrigerators and cooking stoves
* They are common in kitchens, especially when food is left out
overnight, and in restaurants, hotels, bakeries, breweries,
laundries and aboard ships. They are also frequently common in
hospitals. Cockroaches are nocturnal and are rarely seen during
the day unless they are disturbed from their hiding places
what are cockroach eggs called?
Eggs are laid encased in a brown bean-shaped case called
an ootheca which can contain 5–50 eggs but typically 12–
40.
* Cockroaches, especially Blattella germanica, are often seen
running around with an ootheca partly protruding from the
tip of the abdomen
* Oothecae are deposited in cracks and crevices in dark and
secluded places
* Cockroaches live for many months to two or more years,
and during this time females will lay 4–90 oothecae
Cockroaches (Blattaria) – Feeding Behavior
- They are omnivorous and voracious feeders, eating any
type of food. They also eat paper, clothes (particularly
starched ones), books, wall paper, dried blood, sputum,
excreta, dead insects, in fact almost any animal or
vegetable matter - They may gnaw the fingernails and toenails of babies
and sleeping or comatose people, and even infest the
hair of vagrants - They can live for 5–10 weeks without water and for
many months without food
Cockroaches (Blattaria) – Medical Importance
Allergies
* About half of asthmatics are allergic to cockroaches,
their cast-off skins or excreta, while about 10% of nonasthmatic people will exhibit cockroach allergies.
* Symptoms include sneezing, skin reactions, sore eyes,
recurrent ear infections and in extreme cases shortness
of breath
* The allergic rate is second only to that caused by
house-dust mites
(slide 25- for more & alisw 29)
Cockroaches (Blattaria) – Preventive Measures
Ensuring that neither food nor dirty kitchen
utensils are left out overnight will help reduce the
number of cockroaches, but if they are present in
nearby houses, good hygiene in itself will not
prevent them from entering houses
Cockroaches (Blattaria) – Control Measures
Cockroaches have been found resistant to organochlorines, organophosphates,
carbamates and pyrethroids, and resistance to all these groups is known in
Blattella germanica
* Sprays or dusts of the carbamate insecticide bendiocarb and organophosphates
such as malathion and diazinon can be used to control cockroaches.
* Pyrethroids, including permethrin and deltamethrin, applied as sprays can
produce spectacular results in both flushing out and killing cockroaches. Sprays
or aerosols of insect growth regulators (IGRs) such as hydroprene, fenoxycarb
or pyriproxfen, sometimes mixed with pyrethroids, can give a reasonably degree
of control. The relatively new insecticide chlorfenapyr, which as yet has not
been widely used, has also given good control of cockroaches
* Boric acid powder (borax) still remains a very safe and useful chemical, acting
both as a contact insecticide and as a stomach poison (slide 32)
Ants (Hymenoptera) - INTRODUCTION
Ants and wasps, in particular, are among the foremost
predators in regulating insect populations in forest
communities and agroecosystems.
the hymenopterans
of most concern to human health are those that use
their sting apparatus as either an offensive or a
defensive weapon.
* These include many ants, some bees, and certain types
of wasps.
* Even so, most of these stinging species are solitary and
nonaggressive and use their sting and venom primarily
to subdue prey.
Fire Ants
Also known as tropical fire ants (Solenopsis spp.), there are a
variety of stinging ants with over 280 species worldwide.
What is the venom of fire ant called?
Fire ants are known for their lively and aggressive behaviour. They
often attack small animals and kill them subsequently. Fire
ants bite and then sting to inject an alkaloid venom called
solenopsin (a compound from the class piperidines).
* Human will get a sensation similar to fire burning (hence the
name “fire ant”). The sting can be fatal to sensitive individuals
Bullet Ants
Paraponera clavate, commonly known as bullet ant,
named for its extremely painful sting like gun wound!
* The large bullet ant Paraponera clavata of Central and
South America injects venom that produces intense,
debilitating pain lasting several hours. This sting is
considered to be the most painful of all Hymenoptera
(Schmidt, 2016).
slide 37 for more
