Reproductive Potential
Major contributing factor to insect success
High fecundity
Insects lay a lot of eggs
High Fertility occurs when
many of these eggs hatch
Insects are mostly
oviparous: laying eggs
- cockroaches can lay live eggs
Lacewing eggs
help them avoid predators when they lay on leaves
Ametabolous
- no metamorphosis
- Develop with little change to body form
- Primitive Group (Ex. silver fish)
- Adults look largely
Hemimetabolous (no pupal stage)
Incomplete metamorphosis
- Stages: Egg, Nymph, Adult
In Hemimetabolous, what can wings signify
if an adult or a baby
Nymphs who are hemimetabolous resemble
adults that have thin exoskeleton but lack wings
Multiple stages of development in nymphs result in
Nymphal instars
Holometabolous
* most diverse groups undergo this
complete metaphorphosis
Stages: egg, larva, pupa, and adult
Holometabolous: Larvae do what
* maggots = immature flies
exploit different food resources than adults
Adults larvae lay eggs
Directly onto food source so they can begin eating after hatching
Insects consume the most food where?
In the Larvae stage
Excess nutrition storied for adulthood is crucial for
metabolic expensive behaviors known for flight
more energy-> more successful Adult phases
Holometabolous: Pupae
non feeding stage
Pupation can last
* Large beetles have a long pupation
weeks, months or years depending on temp, or species of insect
Diapause
* insects undergo to survive winter
* some dont undergo diapause
reduced metabolisms in response to environmental cues
Stages of Diapause
* shorter days
1. Initiation: Signals prepare for diapause Ex.temp
2. Maintenance: Metabolism slowed; development halted
3. Termination: intensity of diapause decreased
4. Post-diapause: slowed metabolic activity to allow determination of conditions
Insects accumalte special proteins to
lower freezing point in their body like antifreeze
pharate adult
(new adult)
empty pupal exoskeleton
is exuvia
Benefits of Holometabolous Development
* most successful part
- Have longer time to feed
- Reduce their competition btw members of same species
- Diapause allows them to survive longer in environment conditions
Molting Allows
Wound healing { can happen in the immature stages no longer in the adults}
Renewal of exoskeleton
Insect Growth only occurs during
immature stages
- once adulthood reached growth stops
Behavior is often
sex-specific, dimorphic within a species
Reproduction can be viewed from
* takes time
resource perspective; cost and benefits
Sexual selection
* Development of elaborate secondary sexual characteristics
individuals compete for mate access
Mate choice requires one sex to?
and others to have a
Exhibit a trait
heritable perference
Why do some individuals possess traits that seem to reduce survival?
helps them mate alot quicker
Post copulatory sexual selection
occurs through sperm competition and cryptic female choice
Sperm competition
two or more males compete to fertilize an egg
Last male to fertilize females is capable of
fertilizing majority of eggs
Mating plugs prevent
other sperm from accessing eggs, and males will have to expand more resources to remove it
Mating practice
male pierces the abdomen of the female to avoid mating plug called Traumatic insemination
Traumatic insemination
sperm is carried through hemolymph
and is transferred due to open circulatory system
Adaption of mating plug leads to
- less time of courtship
- sperm gets closer to ovaries
Female Adapation:
Spermalege
sperm receptacles at site of penetration
Ectospermalege
* help restrict injury
visible external target
Mesospermalege
* help restrict injury
sac attached to inner abdomen under ectospermalege