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Announcements• Lab quiz next Monday• Insect collections to be returned in lab• Tips for a good collection

– Insects pinned and labeled asshown in guidelines

– Enough insects collected– Good presentation of specimens

Nice collections

Last lecture• Kinds of sexual selection

– Intrasexual• Male male competition

– Contest competition– Scramble competition

• Sperm competition– Intersexual- female choice

• Reproductive conflict between sexes• Outcomes of sexual selection• Case of willow leaf beetle

Questions about leaf beetlestudy?

Ovipositor Structure Ovipositor Modifications

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Ichneumon Insect reproduction• Types of offspring produced

– Oviparity-eggs travel down oviduct, arefertilized, and laid

– Oviviparity- eggs incubate insidereproductive tract of female beforelaying

– Viviparity- ‘live’ birth, where larvaedevelop inside female

• Parthenogenesis• Hermaphroditism in insects• Effects of vertically transmitted bacteria on

reproduction

Viparity: Egg laying• Oviparity

– Laying initiates egg development

Viviparity– initiation of egg developmenttakes place in female

Parthenogenesis• Females produce viable unfertilized

eggs• Found in nearly all insect orders

Leaf beetle genus Oreina• Found in Europe• All three reproductive

strategies found inone genus

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Parthenogenesis• Types

– Obligatory– Facultative

• Seasonal in aphids– Asexualreproductionduring summer

– Sexualreproduction inSpring and fall

Variation in reproduction

larvaeO. variabilis

eggsO. elongata

larvaeO. cacaliae

Parthenogenesis in Hymenoptera

• Sex determination– Haploid = male– Diploid = female

• Mechanism– Female letssperm fertilizeeggs, female

– With nofertilization,male

Bumblebee life cycle Ant life cycle