Lecture 13

Question 1

What are the reproductive behavior (steps to sex and beyond)?

Answer 1

A) Locating a mate
B) Courting the potential mate
C) Sexual Selection (gamete transfer)
D) Bizarre sexual world of insects
i)Nuptial Gifts from male to female (receipt of food)
a. attractive to chemicals (candymaker hypothesis)
b. male cannibalization
c. puddling
ii) Modifies appendages of males for grasping and contact
iii) Spine on aedeagus, Wound female during sex (reduce re-mating and
stimulate oviposition)(Elm leaf beetle)
iv) Traumatic Insemination: Male pierce female abdomen with aedeagus and ejaculates in hemolymph
(spiders, flatworms, stepsiptera)
v) Copulatory wheel (odanata)
E) Sperm Competition
i) multiple mates
ii) Occurs in female tract
iii) Sperm precedence
a. displace other sperm, last one is the first one out
b. remove sperm by scraping
c. Mating switches off secretions, guarding, grasping
F) Oviparity (Oviparous=egg laying)
G) Viviparity (Viviparous=live birth)
H) Other modes of reproduction

Question 2

Hanging scorpionfly (Order Mecoptera; Family Bittacidae)

Answer 2

Nuptial gift (Duration of mating related to size of gift)
-Bigger the size, longer it takes to unwrap

Question 3

Nuptial Gift

Answer 3

• The dagger fly (Family Empididae) has ritual where male gives ball of silk to female. Unravels ball while mating. Also a way to divert agressiveness so insemination can occur.
• Primitive species have the nuptial gift as item of prey that female can eat
• Advanced species, male wrap silk to buy time for copulation. Outsmart the female’s innate response.

Question 4

Candymaker Hypothesis

Answer 4

• Many male katydids (Orthoptera: Tettigoniidae) and crickets (Orthoptera: Gryllidae) transfer eleborate spermatophores, attached externally
• Spermatophore has the spermatophylax which is eaten after mating and the sperm ampulla is eaten after that and when sperm is transferred
• During consumption of spermatophylax, sperm is transferred from ampulla and substances ingested or transferred that turn off female receptivity
• Insemination stimulates oviposition so that the male fertilizing has a higher chance of being the father

Question 5

Male Canabalism

Answer 5

• Most famous praying mantis who eats male head
• Only 25% of males eaten by females of all insects
• Provides nutrition to make eggs and for the offspring

Question 6

Puddling

Answer 6

• Lepidoptera and Coleoptera get metabolically essential substances during copulation from male
• Chemicals transferred from ejaculate of male
• Form of parental investment
• Male butterflies and moths drink pools of liquid, this is puddling
• Allows uptake of minerals like sodium that are lacking in larval stage or even nitrogen.
• Temperate Butterflies can seek salts and others (tropical) seek protein (nitrogen) sources

Question 7

Benefits from nuptial gifts?

Answer 7

• Better egg production
• Better female longevity
• Parental investment for male
• Can increase male fertility success

Question 8

Modification in Males

Answer 8

• Good example in water striders- Has crooked legs used for clasping on the female body
• Males can have traumatic insemination (bedbugs) where male pierce abdomen with aedeagus in abdomen and ejaculates. Also males have spine in aedeagus to wound female during sex to reduce her mating again and stimulates the oviposition
• Bedbugs perforate at special sites called spermalege
• Extermal swelling (ectospermalege) filled with hemocytes and directs site of penetration
• Mesospermalege is a sac in abdomen that holds sperm until it transfers it to ovaries

Question 9

Odanata

Answer 9

• Copulatory Wheel
• Males deposit spermatophore on 2nd abdominal sternite
• Male clasps on female behind head when makes her curve abdomen towards him
• Female places genital opening over spermatophore and takes it in vulva
• Can happen many places like water

Question 10

Sperm precedence

Answer 10

We have the pernis and horn of penis going inside. First it enters vagina and there is a huge sac inside called bursa copulatrix. Oviducts look like tubes and spermatheca is like horns.

Question 11

Oviparity

Answer 11

• Oviparous=egg laying
• Ovipositor aids in the egg laying (digging, parasitoids use it, stinging)
• Majority of insects do this
• egg structure includes a nucleus, a yolk, chorion (wall), and micropyle (how sperm enters)
• Ootheca(orthoptera, cockroach as well) egg case
• Incredible numbers with ootheca (honeybee queen 2000 a day, 100,000 in a life)(termite queen 30,000 a day, 164 million in a life)

Question 12

Viviparity

Answer 12

• The live birth
• There is the combined method of the two, oviparity+viviparity= ovoviviparous: embryo is in a egg and hatches in female
• Something called pseudoplacental viviparity: yolk deficient egg, mother provides placenta-like tissue
• Haemocoelous viviparity: Embryos develop in haemolymph
• Adenotrophic viviparity: feeding from milk glands

Question 13

Other modes of reproduction

Answer 13

-Parthenogenesis- nonfertilized eggs 
 Three types: Thelytoky(female), Arrhentoky(male), Deuterotoky(male and female)
-Paedogenesis (larval and pupal)
-Hermaphrodism: ovatestis
-Endosymbionts: Wolbachia