Lecture 9 Flashcards
What order are ground beetles in?
coleoptera
what is unique to the beetle order coleoptera?
have elytra: hardened forewings for protection
unique to this order
what type of mouthparts do beetles have?
biting chewing
what type of development do beetles have?
holometabolous
what family are ground beetles in?
carabidae
where is the elytra attached & what does it cover?
attached to the pro-thorax
cover the abdomen, meso-thorax & meta-thorax
what is unique about the ground beetle?
5 tarsal segments on all legs
thread-like antennae with 11 segments
describe the elytra of Chlaenius cordicollis
have fine hairs - unique
describe the colouring of Chlaenius cordicollis
very shiny when young, become darker with age - shine wears off when pushing through rocks
what is the location of ground beetles?
MB & east Minnesota to the Atlantic coast
describe the habitat of Chlaenius cordicollis
lakeshores & river banks with limestone slabs
describe the activity of Chlaenius cordicollis during the days & nights
days - hide in grps under slabs
night - active on the surface
how do males & females differ in Chlaenius cordicollis?
female legs - narrow
male legs - broader, brush-like segments enabling them to hold on & grip to a female when mating
describe the eggs of Chlaenius cordicollis
Unprotected when deposited
Eggs are cemented singly to a stone (occasionally 1-2 together)
describe the larvae of the ground beetle
head is the only hard part
soft tissue = growing, almost done instar
sclerites
Urogomphi
how many instars to ground beetles have?
3
sclerites
hard plates with soft cuticle b/w them on the thorax & cuticle
larvae
Urogomphi
extended segment at the posterior of the abdomen, function uk but believed that’s used for communication
the larval instar can be determined by the ______
measurement of a sclerotized organ
dyar’s rule
the ratio of dimensions of sclerotized organs (head, spiracles etc.) of adjacent instars of immature insects is relatively constant
describe the pupa of a ground beetle
can see mandibles & legs
cuticle begins to harden & the beetle gets darker
what is the name of the PRO that hardens & darkens in the cuticle?
sclerotin
describe the teneral adult stage in the first 12 hr period
Elytra – white
Head capsule not darkened
describe the teneral adult stage in the first 30 hr period
Head capsule darker
Mandibles are hard enough to break up food & function properly
Wings are present but not hardened, therefore cannot use for flight
describe the teneral adult stage in the first 3 days
Insect appears like an adult
Still can’t fly (wings are still soft)
2 weeks from this time when they can fly
what can a ground beetle fly?
weeks from the 3 day teneral adult stage
how long does it take for the larval instar stages to be completed?
30 days
teneral adult
adults that can’t fly
when do the beetles mate?
June-July
what stage has never been observed in nature?
pupa
how long is the egg stage?
7 days
how long is the pupa stage?
9 days
describe the eating behaviour
scavenger insects (usually don’t attack live prey)
lakes act as conveyor belts feeding the beach-dwelling insects
what do the ground beetles feed on that the lake washes up on shore?
Insects falling in the lake when trying to fly
Feed on fish flies that wash up when emerging from the bottom of the lake
Mid-summer diet is dominated by _____
fish flies
when the ground beetles feed on the fish flies, what are they eating in particular?
dead adults
exuviae from emergence
blowfly larvae feeding on the above (what’s flying)
in ____ adults disappear from the beach
early or mid-Sept
Adults move to the top of the beach by mid-Sept - why?
Temp in Sept lowers, therefore their metabolic rate does as well
They can’t run as fast & outrun the waves like they do in the spring & summer
If they aren’t well up the beach at this point then they’re at risk of drowning
what is a mechanism of freeze avoidance in ground beetles ?
cease feeding in Sept & gut is empty
average freezing point?
-2C
average supercooling point?
-4C
lowest supercooling point?
-7.6C
how do you know when a female ground beetle is in a reproductive state?
have distended abdomens
cuticle is separated from the abdomen
what cue initiates reproductive physiology?
day length
what day length did they start to see females in their reproductive state?
17hr
