Lecture 8b: Symbiosis

Question 1

Scientific name of wasps

Answer 1

Sirex nocilio

Question 2

Which trees do these wasps associate with

Answer 2

Pine trees
pinus species

Question 3

Which fungal species associates with pine trees

Answer 3

Amylostereum areolatum

Question 4

Life cycle of siren noctilio

Answer 4

• Female injects eggs into weak/damaged tress into their sapwood
• Eggs pass through the mucus gland picking up some of the toxic mucus
• Eggs pass by the mycangium picking up some fungal spores
• Larvae feed off the fungus and the cellulolytic breakdown products of the wood
• After pupation a new batch of adults are produced
• As females emerge they collect spores and repeat the cycles of inoculation into other trees

Question 5

Symptoms on trees cased by the wasps and fungi

Answer 5

• Resin flow from oviposition sites
• Chlorosis in the crown
  *wilting of foliage and finally death/decay
• Fungal growth causes wood to dry out and disrupts water movement
• White discolouration

Question 6

Control

Answer 6

• Selection of resistant/tolerant phenotypes
• Thinning- removes diseased trees
• Prevention of wounds and stress

Question 7

Biological control of wasps

Answer 7

Deladenus nematodes

Question 8

How do deladenus control the growth and spreading of Sirex

Answer 8

They make male and female wasps infertile

Question 9

Species name of the beetle and it’s symbiont fungi

Answer 9

Euwallacea fornicates (PSHB)-beetle
Fusarium euwallacae- fungi

Question 10

What were the first reported losses cause by the beetle and fungi symbionts

Answer 10

Avocado in Israel

Question 11

PSHB and symbiont life cycle

Answer 11

• Beetle tunnel into trees where galleries are made
• They carry symbiont fungi to the xylem tissue where the fungus is cultivated as a food source
• the fungus provides aa, sugars and sterols required for completion of beetle lifecycles

Question 12

Symbiosis

Answer 12

• Fungus guaranteed transport and access to food resources
• Beetle is able to survive in a nutritionally poor resource and is protected from the environment since it is in the tree

Question 13

Reproductive hosts

Answer 13

Host species in which successful reproduction occurs

Question 14

Non-reproductive hosts

Answer 14

Host species in which the beetle is able to establish a gallery and survive but not successfully reproduce

Question 15

What is the reproductive success linked to

Answer 15

The susceptibility of the host to colonisation by the fungal symbiont