Chapter 10 Flashcards
- Bugs
- Beetles
- Bugs (Hemiptera)
- Beetles (Coleoptera)
what does the name Hemiptera mean?
The name Hemiptera means ‘halfwing’ which refers
to the fact that part of the first pair of wings is
toughened and hard, while the rest of the first pair
and the second pair are membranous
What are some facts about bed bug, Cimex lectularius?
- It lives in bedding and is mainly active at night, feeding
on human blood, generally without being noticed
Bed bugs mate by traumatic insemination;
Explain how the male bed bugs inseminate the females bed bugs.
Bed bugs mate by traumatic insemination; the male
pierces the female’s abdomen and injects his sperm
into a secondary genital structure (spermalege)
* The sperm travel in the female’s blood (haemolymph)
to sperm storage structures (seminal conceptacles);
they are released from there to fertilise her eggs inside
her ovaries
(see slide 20)
The family Cimicidae includes bed bugs, of which
two common species feed on human. What are they?
Cimex lectularius is widely distributed in tropical
and nontropical countries while C. hemipterus,
commonly called the tropical bed bug, is essentially
a species of the Old and New World tropics
What is the species of the family Cimicidae?
A third species, Leptocimex boueti, is found mainly
in West Africa but has also been recorded in South
America. This species bites bats and also people,
but is much less important as a pest than the Cimex
species
When did the Infestations of bed bugs start to increase?
- Infestations of bed bugs have increased since the
1990s in many countries, possibly due to increased
global travel. For instance, after the 2000 Olympic
Games nearly every hotel in Sydney was infested
with bed bugs
What are other ways bed bugs?
- Bed bugs are usually spread to new houses by
being introduced with furniture and bedding, or
more rarely with clothing and hand baggage.
Buying second hand furniture can result in the
introduction of bed bugs into houses
State morphologies of bed bugs.
- Adult bed bugs are oval, wingless insects which are
flattened dorsoventrally - The head is short and broad and has a pair of
prominent compound eyes - The prothorax is much larger than the meso- and
metathorax - Bed bugs lack wings so they do not disperse far
How many wings do bed bugs have?
Two rudimentary and non-functional more or less oval
wing pads, termed hemelytra, overlie the meso- and
metathorax
Difference between the morphology of female bed bugs and male bed bugs
In adult males the tip of the abdomen is slightly more
pointed than in females, while closer examination
shows a small well-developed curved penis
* In females there is a small incision ventrally on the left
side of the apparent fourth abdominal segment. This
opens into a special pouch (=sinus) called the
mesospermalege, organ of Berlese or organ of Ribaga,
which collects and stores sperm
* Because both male and female bugs bite it is not
medically very important to distinguish the sexes
What happens to bed bugs during the day and night?
During the day adults and nymphs are inactive and hide in dark
and dry places, such as cracks and crevices in furniture, walls,
ceilings or floor boards, underneath seams of wallpaper and
between mattresses and beds. At night adults and nymphs
emerge to feed on sleeping people, after which they return to
their resting sites to digest their blood-meals. Bed bugs are
gregarious and are frequently found in large numbers. They can
move quite rapidly when disturbed
Bed Bugs (Hemiptera) – Life Cycle
- Females lay about 2–4 eggs a day in cracks and
crevices of buildings and furniture, but egg-laying
ceases at 13° C or lower. Females live several weeks
to many months, and occasionally a year or more,
and during this time they may lay 150–540 eggs - Eggs usually hatch after about 8–11 days
- Newly hatched bed bugs (nymphs) are very pale
yellow and resemble adults, but are much smaller - The life cycle is hemimetabolous and there are five
nymphal instars each lasting 3–10 days.
The nymphal period lasts 2–7 weeks - The life cycle, from egg to adult, can be just 3–4
weeks if temperatures are high and food plentiful,
but is more usually 6–10 weeks - In the laboratory adults can live for four years, and
survive more than a year without blood-feeding
Bed Bugs (Hemiptera) – Life Cycle
Bed Bugs (Hemiptera) – Medical Importance
- Although hepatitis B virus and 27 other pathogens
have been recorded in bed bugs there is no
evidence that they can transmit any infections to
people. They are therefore not considered as
vectors
Can bed bugs cause iron deficiency?
Some people show little or no reaction to their
bites, but others may suffer severe reactions and
have sleepless nights. Repeated feedings of large
numbers of bed bugs can cause iron deficiency in
infants and some elderly people
What are some physical measures that can be implemented to control bed bugs?
If bed clothes are infested they should be washed
in hot water then ironed or dried in the sun.
* Alternatively clothes can be placed in sealed plastic
bags and placed in a freezer (–18°C) for 24 hours to
kill the bed bugs
What are some chemical measures that can be implemented to control bed bugs?
Insect repellents and insecticide-impregnated bednets can give considerable personal protection
against bed bugs
- Floors and walls of infested houses, together with
as much furniture as possible, should be sprayed
with the carbamate bendiocarb,
organophosphates such as malathion, a range of
pyrethroids including cypermethrin and also insect
growth regulators (IGRs) such as methoprene
Commercially available small insecticidal smoke bombs
containing insecticides, such as permethrin, which burn for
up to 15 minutes, can be used to fumigate infested premises
Bed clothes and infants’ mattresses should be treated
with insecticides. True or false.
False
What causes Trypanosoma cruzi?
Two of the
main vectors are Triatoma dimidiate
and Rhodnius prolixus, which are not so endophilic, indoor
residual spraying is not so effective.
Triatomine Bugs (Hemiptera) - INTRODUCTION
- Blood-sucking bugs in the family Reduviidae belong to
the subfamily Triatominae
The most important are Triatoma infestans, T.
dimidiata, Rhodnius prolixus and Panstrongylus
megistus, all of which spread Chagas disease
(Trypanosoma cruzi) in Central and South America
Triatomines are commonly called
kissing-bugs, conenose bugs, vinchucas or barbeiros
Triatomine Bugs (Hemiptera) - Morphologies
Triatominae vary from 5 to 45 mm in length, but
most are 20–30 mm long
They are easily recognized by their long snout-like
head having a pair of prominent dark-coloured
eyes, in front of which is a pair of laterally situated,
long and thin four-segmented antennae
The proboscis, sometimes called the rostrum, is
relatively thin and straight
The dorsal part of the first thoracic segment of the
Triatominae consists of a very conspicuous
triangular pronotum
The meso- and metathorax are hidden dorsally by
the folded fore-wings, called hemelytra
The basal part of each hemelytron is thickened and
relatively hard, whereas the more distal part is
membranous
- Hind-wings are entirely membranous, but when
the bug is not flying they remain hidden
underneath the hemelytra - Triatominae are frequently a brown-black colour,
but some species are more colourful
Triatomine Bugs (Hemiptera) – Life Cycle
Typically females lay 1–2 eggs a day. The total number
laid varies from 50 to 1000, depending on the species,
their longevity and the number of blood-meals they
take, but it is usually 200–300
- The life cycle is hemimetabolous. Small pale nymphs, which
resemble adults but lack wings, may hatch from eggs after
only 10–15 days - Newly emerged nymphs usually remain hidden in cracks and
crevices for 2–3 days before they blood-feed - There are five nymphal instars, each requiring at least one
blood-meal before it changes into the succeeding instar - Rudimentary wing pads are visible in the fourth and fifth
nymphal stages, but only adults have fully developed
wings. Young nymphs can ingest 6–12 times their own
weight of blood, and their abdomens may become so
greatly distended that they resemble blood-red balloons
Triatomine Bugs (Hemiptera) – Feeding Behavior
- Adults of some species ingest 300–400 mg of blood at
each meal and feed every 4–9 days! Sometimes hungry
nymphs and adult bugs pierce the swollen abdomens of
freshly engorged nymphs and take a blood-meal from
them, without apparently causing harm
Nymphs and adults of both sexes feed at night on
their hosts, and feeding often lasts 10–25 minutes.
People covered with blankets are bitten on any exposed
parts of the body, but especially on the nose and
around the eyes and mouth. Biting is usually relatively
painless and does not awaken people
- Many bugs defecate during or soon after feeding, and
this behaviour is very important in the transmission of
Chagas disease - Presence of bugs in houses is often characterized by
finding shed skins (exuvia) from moulting nymphs and
streaks of whitish or dark faecal deposits on walls and
furniture - Because of the relatively long time required to digest
their large bloodmeals, the life cycle from egg to adult
can take 3–10 months. With large triatomine species
the life cycle may last 1–2 years. In the absence of
hosts, older nymphs and adults can survive 4–6 months
of starvation
slide 39 for more
