Phases of insect diapause Diapause

1 phases of insect diapause

1.1 comparison of diapause periods
1.2 induction
1.3 preparation
1.4 initiation
1.5 maintenance
1.6 termination
1.7 post-diapause quiescence

phases of insect diapause

diapause in insects dynamic process consisting of several distinct phases. while diapause varies considerably 1 taxon of insects another, these phases can characterized particular sets of metabolic processes , responsiveness of insect environmental stimuli. diapause can occur during stage of development in arthropods, each species exhibits diapause in specific phases of development. reduced oxygen consumption typical reduced movement , feeding. in polistes exclamans queen said able undergo diapause.

comparison of diapause periods

the sensitive stage period when stimulus must occur trigger diapause in organism. examples of sensitive stage/diapause periods in various insects:

induction

the induction phase occurs @ genetically predetermined stage of life, , occurs in advance of environmental stress. sensitive stage may occur within lifetime of diapausing individual, or in preceding generations, particularly in egg diapause. during phase, insects responsive external cues called token stimuli, trigger switch direct development pathways diapause pathways. token stimuli can consist of changes in photoperiod, thermoperiod, or allelochemicals food plants. these stimuli not in favourable or unfavourable development, herald impending change in environmental conditions.

preparation

the preparation phase follows induction phase, though insects may go directly induction initiation without preparation phase. during phase, insects accumulate , store molecules such lipids, proteins, , carbohydrates. these molecules used maintain insect throughout diapause , provide fuel development following diapause termination. composition of cuticle may altered changing hydrocarbon composition , adding lipids reduce water loss, making organism resistant desiccation. diapausing puparia of flesh fly, sarcophaga crassipalpis, increase amount of cuticular hydrocarbons lining puparium, reducing ability of water cross cuticle.

initiation

photoperiod important stimulus initiating diapause. initiation phase begins when morphological development ceases. in cases, change may distinct , can involve moulting specific diapause stage, or accompanied color change. enzymatic changes may take place in preparation cold hardening. example, diapausing adults of fire bug, pyrrhocoris apterus, have enzymatic complement allows them accumulate polyhydric alcohols, molecules lower freezing points , avoid freezing. insects may undergo behavioural changes , begin aggregate, migrate, or search suitable overwintering sites.

overwintering monarch butterflies in diapause clustering on oyamel trees. 1 tree covered in butterflies. these butterflies located on preserve outside of angangueo, michoacán, mexico


maintenance

during maintenance phase, insects experience lowered metabolism , developmental arrest maintained. sensitivity stimuli act prevent termination of diapause, such photoperiod , temperature, increased. @ stage, insects unresponsive changes in environment trigger end of diapause, grow more sensitive these stimuli time progresses.

termination

in insects undergo obligate diapause, termination may occur spontaneously, without external stimuli. in facultative diapausers, token stimuli must occur terminate diapause. these stimuli may include chilling, freezing, or contact water, depending on environmental conditions being avoided. these stimuli important in preventing insect terminating diapause soon, instance in response warm weather in late fall. in edith s checkerspot butterfly, individuals must receive enough sunlight in order terminate diapause stage , become grown butterfly. termination may occur @ height of unfavourable conditions, such in middle of winter. on time, depth of diapause decreases until direct development can resume, if conditions favourable.

post-diapause quiescence

diapause ends prior end of unfavourable conditions , followed state of quiescence insect can arouse , begin direct development, should conditions change become more favourable. allows insect continue withstand harsh conditions while being ready take advantage of conditions rapidly possible.