Feb 24 lecture handout

Feb 24 lecture handout - Alternating Strategy: Soybean...

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1 Alternating Strategy: Soybean Aphid • Heteroecious: alternates between more than one host plant in an annual cycle • Holocyclic: has sexual reproduction in part of the annual life cycle • Important pest of soybean in midwestern US • Soybean summer host (Secondary host) • Buckthorn winter host (Primary host) Distribution of Soybean Aphid More Current Distribution
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2 The Life Cycle •Sp r ing – Winter host is Buckthorn (Ramnus spp.) – Nymphs hatch from eggs and develop into fundatrices (singular: fundatrix) – Adults produce second generation of singless, parthenogenetic females – Third and later generations on Ramnus are winged parthenogenetic females – Winged females move to summer host -
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3 Developing Spring Colony The Life Cycle • Summer – Many overlapping parthenogenetic generations produced – Winged females ( alates ) are produced in response to crowding or declining nutritional value of the host plant – New host plants are colonized regularly
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4 The Life Cycle • Autumn – Shortening photoperiod causes production of gynoparae (special winged females) that fly from soybean in search of Ramnus –On Ramnus , gynoparae produce numphs that develop into oviparae (sexual females) – Males are produced on soybean at the same time as gynoparae – Males leave soybean in search of Ramnus and mate with oviparae – Oviparae oviposit overwintering eggs on Ramnus Soybean Ovipara laying egg
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5 The Life Cycle •W
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This note was uploaded on 03/21/2012 for the course ENTOMOLOGY 104 taught by Professor Lewis during the Spring '12 term at UC Davis.

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Feb 24 lecture handout - Alternating Strategy: Soybean...

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