Insect_Mating_Ent1_2008 - Mating Games: Finding a Mate,...

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Unformatted text preview: Mating Games: Finding a Mate, Mating Behavior and Reproduction Lecture Goals The fascination with insect mating How do insects reproduce? Asexual and sexual reproduction Reproductive anatomy Implications of single and multiple mating Sperm transfer and storage Courtship and mating Parental Care Green Porno Star Isabella Rossellini Takes on Insect Sex A series of short films by Isabella Rossellini “I was always fascinated by the infinite, strange and ‘scandalous’ ways that insects copulate.” 1 Two Types of Asexual Reproduction All insects are female, live young are produced. Aphids Two Types of Asexual Reproduction Haplodiploidy Honey bees: unfertilized eggs = males (drones). (drones) 2 Sexual Reproduction Most insects reproduce sexually. Mating involves sperm transfer from males to females and involves several activities: Location of one sex by the other (see insect communication) Courtship Pairing Copulation and insemination Making More Insects: Reproductive Anatomy Female Reproductive Anatomy Storage organ for sperm, honey bee queens may store sperm for as long as 25 years. 3 Male Reproductive Anatomy: Diverse morphologies. Varied V i d orientations. Useful for identification of some species. Making More Insects: Finding Mates How do insects attract and recognize their mates? Chemistry, Vision, Sound Courtship Rituals 4 How do insects attract and recognize their mates? Male leks Aggregation (lek) of male shieldbugs, Alien Empire (lek) shieldbugs, Courtship Rituals Why a courtship ritual? A courting pair of robberflies, Alien Empire Courtship Gifts This unnamed bush cricket from Brazil is eating the spermatophylax donated by the male during mating. --from --from Alien Empire After direct insemination, males of some insects deposit material that remains external t i t l to the female (spermatophylax). This is highly nutritious and is usually consumed by the female. 5 This female scorpionfly is eating a fly captured previously by the male. The male offers this as a nuptial gift. The larger the gift, the longer the female will mate. If f l ill t she eats the gift before mating is complete she is quite capable of terminating copulation before sperm transfer is complete. --from --from Alien Empire Male danceflies wrap a variety of nonnon-edible materials in silk and offer it as a gift. Males often snatch the gift away from the female when mating is complete and use it again in subsequent mating. Males also try to steal gifts from other males. --from --from Alien Empire Making More Insects: Pairing and Copulation 6 Mating Implications of single or multiple matings Fitness, relationships between offspring How do males insure that their sperm will be used to fertilize eggs? •Some males may remove sperm deposited in the female from other males •May try to prevent additional mating •May carry fertilized eggs for the female Pairing and copulation Indirect insemination: Male produces a capsule containing the sperm. Capsule, droplet of sperm on a stalk, more complex structure. Males may place the sperm capsule on the ground independent of female presence, or elaborate methods to guide the female to the sperm Females then insert the sperm into their reproductive opening. Direct insemination: Among some insects, the males may insert the spermatophore or it can form during copulation. Spermatophore Diversity 7 Sexual Reproduction Direct Insemination: with or without a spermatophore. spermatophore. Female still stores sperm in a special internal container (spermatheca). (spermatheca). Males of many species either die after mating or risk being eaten by the female female. For example, the male dancing fly offers his mate a diversionary tidbit to eat during mating. Less lucky are male biting midgesmidgesthe female sucks out the contents of the males body while he is in the process of mating. Making More Insects: Reproduction and Caring for Offspring Egg Laying Females have special structures for laying eggs (ovipositor). Eggs may be laid on the surfaces or embedded in plants or other substances. 8 Egg Laying The ovipositor is usually adapted for piercing the substance in which the eggs must be laid. It can be many times the length of the insect. Egg Laying On the left, the very long ovipositor of a wasp that lays it’s eggs in wood. Some bees and wasps use their stinger as an ovipositor and invert it when not in use. On the right, the eggs of a grasshopper, laid in a tunnel in the ground. Parental Care Most insects lay their eggs and then leave them to develop without any parental care. ih l Some insects: Protect their eggs. Protect and feed their offspring. 9 Parental Care Parental care is usually performed by females, the male shieldbug is an exception, guarding the eggs of its mate and protecting them from wasp parasitoids. Parental Care Female shieldbugs guard their offspring while they feed (left). Female fungus beetles guard their offspring and guide them to the fungi on which they feed (right). Parental Care The Cape Mountain cockroach from South Africa gives birth to live young and remain with their offspring until they can fend for themselves. 10 Solitary Bees and Wasps A solitary bee seals her mud nest which she provisioned and inserted a single egg (left). A solitary wasp uses a pellet of earth to tamp her nest closed. She provisioned the nest with paralyzed caterpillars. Sociality: the Most Sophisticated Parental Care Bees Ants Termites Questions about insect reproduction: – What is the importance of insect fecundity to their success? – How do insects with very short lives enhance their ability to find one another and mate? – How does our culture and impact on the environment interfere with insect mating? 11 ...
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This note was uploaded on 10/03/2009 for the course ENT 1 taught by Professor Ullman during the Fall '08 term at UC Davis.

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