Insect ReproductionCh. 4 Introduction to Insect Biology and Diversity

Tracey Anderson 12-01-2010

Male Organs

Reproductive Organs

Courtesy of Dr. Ken Hobson, University of Oklahoma

Female Organs

Reproductive Organs cont.

Courtesy of Dr. Ken Hobson, University of Oklahoma

Do the reproductive organs in insects resemble any other organisms?

What about humans (Homo sapiens)?

Reproductive Organs cont.

Courtesy of http://www.health-res.com/EX/07-27-22/internalfemalepelvic.jpg

Courtesy of http://www.1cro.com/Diversity/malerepro_1.gif

“The Universe is not only queerer than we suppose, but queerer than we can suppose " J.B.S. Haldane

It is not surprising that with the huge numbers of insects, evolution has produced many different reproductive avenues

Oviparity • Generally what is thought of when considering insect

reproduction• Most common form• Eggs are deposited after fertilization. Eggs’ nutrition comes

from yolk• Used by most insect. Ex. Largest order of insect the beetles

Types of Reproduction

Information in the next sections are from the textbook and courtesy of Dr. Ken Hobson, University of Oklahoma

Courtesy of http://denimpine.com/documents/pine_beetle_web1.jpg

Ovoviparity • Fertilized egg is held in reproductive tract of

female until completely developed • Nutrition comes from yolk • Used by some beetles and flies

Courtesy of Dr. Ken Hobson, Univ. of Oklahoma

Viviparity • Analogous to animal reproduction• Egg held in female productive tract like

ovoviparity but nourished by mother• Some flies, aphids, earwigs, and some roaches

Courtesy of http://webdocs.cs.ualberta.ca/~games/aphid/gifs/aphids.gif

Courtesy of http://www.insectsofalberta.com/images/2006-apr-3_earwig.jpg

Parthenogenesis • Production of progeny from unfertilized egg• Asexual reproduction• Favorable in constant environment which natural

selection is not necessary to help increase fitness• Production of males: bees wasps• Production of females: walking sticks

Courtesy of http://www.animalpicturesarchive.com/animal/a7/New_Zealand_Walking_Stick-by_Tom_Pesendorfer.jpg

Paedogenesis • Unusual reproductive avenue used when

resources are scare• Scarce resources caused larval ovaries to produce

eggs which develop parthogenetically • Midge flies

Courtesy of http://www.grahamowengallery.com/fishing/midge-2-large.jpg

Offspring are genetically identical to parent This is advantageous in a constant

environment. Parent would be fit, so offspring would likely be fit, too

Natural selection would favor genetic diversity (sexual reproduction) in a changing environment

Parthenogenesis

Bees (Order Hymenoptera) have a reproductive pattern known as “Haplo-diploidy”

Females are produced “normally” with union of egg and sperm

Males are produced from unfertilized eggs◦ Males would have 1 parent, 2 grandparents, 3

great-grandparents, 5 great-great-grandparents (interesting pattern, huh?)

Parthenogenesis cont.

It was once believed that the evolution of sociality in Hymenoptera was due to haplo-diploidy

Females were more closely related to sisters than to offspring

It was thought that it was more advantageous to look after sisters than to reproduce

Recently proven to be false

Haplo-Diploidy and the evolution of sociality