Lecture 7: Role of pollinators, weed killers and other beneficial insects
I. Role of pollinators
Pollination refers to the transfer of anther to stigma in flowering plants for sexual
reproduction.
Insects aid in cross pollination in fruits, vegetables, ornamentals, cotton, tobacco,
sunflower and many other crops.
Insect pollination helps in uniform seed set, improvement in quality and increase
in crop yield.
Entomophily refers to cross pollination aided by insects
Pollination classes Type of insects
Melitophily Bees
Cantharophily Beetles
Myophily Syrphid and Bombylid flies
Sphigophily Hawk moths
Psychophily Butterflies
Phalaeophily Small moths
1.Honeybees as pollinators
All bee species aid in pollination
Value of honey bees in pollination is 15-20 times higher than that of the honey
and wax it produces.
Per cent increase in yield due to bee pollination
Mustard - 43%
Sunflower - 32 - 48%
Cotton - 17 - 19%
Lucerne - 112%
Onion - 93%
Apple - 44%
Cardamom - 21-37%
2. Hoverflies Syrphus sp. (Syrphidae:Diptera)
Brightly coloured flies
Body is striped or banded with yellow or blue
Resemble bees and wasps
Larval stage predatory, adults are pollinators
Crops pollinated - carrot, cotton, pulses
3.Carpenter bee, Xylocopa sp. (Xylocopinae:Anthophoridae)
, Robust dark bluish bees with hairy body
Dorsum of abdomen bare, pollen basket absent
Adults are good pollinators
Construct galleries in wood and store honey and pollen
4. Digger bees, Anthophora sp. (Anthophoridae:Hymenoptera)
Stout, hairy, pollen collecting bees
Abdomen with black and blue bands
5. Fig wasp Blastophaga psenes (Agaonitae:Hymenoptera)
Fig is pollinated by fig wasp only. There is no other mode of pollination.
There are two types of fig Caprifig and Symrna fig.
(i) Caprifig
a. It is a wild type of fig - not edible
b. Has both male and female flowers
c. Pollen is produced in plenty
d. Natural host of fig wasp
(ii) Smyrnafig
a. It is the cultivated type of fig - Edible
b. It has only female flowers
c. Pollen not produced
d. Not the natural host of fig wasp
Fig wasp: Male - wingless, present in caprifig
Female - winged
wasp lays eggs in caprifig, larvae develops in galls in the base of the flowers
mates with female even when the is inside gall
Mated wasp emerges out of flower (caprifig) with lot of pollen dusted around its
body.
The fig wasp enters smyrna fig with lot of pollen and deposits it on the stigma
But it cannot oviposit in the ovary of symrna fig which is deep seated
It again moves to capri fig for egg laying. In this process smyrna fig is pollinated
Caprifig will be planted next to smyrna fig to aid in pollination
6. Oil palm pollinating weevil: Elacidobins kamerunicus (Curculionidae :
Coleoptera)
Aid in increasing oil palm bunch weight by 35% and oil content by 20%
7. Other pollinators
I. Role of pollinators
Pollination refers to the transfer of anther to stigma in flowering plants for sexual
reproduction.
Insects aid in cross pollination in fruits, vegetables, ornamentals, cotton, tobacco,
sunflower and many other crops.
Insect pollination helps in uniform seed set, improvement in quality and increase
in crop yield.
Entomophily refers to cross pollination aided by insects
Pollination classes Type of insects
Melitophily Bees
Cantharophily Beetles
Myophily Syrphid and Bombylid flies
Sphigophily Hawk moths
Psychophily Butterflies
Phalaeophily Small moths
1.Honeybees as pollinators
All bee species aid in pollination
Value of honey bees in pollination is 15-20 times higher than that of the honey
and wax it produces.
Per cent increase in yield due to bee pollination
Mustard - 43%
Sunflower - 32 - 48%
Cotton - 17 - 19%
Lucerne - 112%
Onion - 93%
Apple - 44%
Cardamom - 21-37%
2. Hoverflies Syrphus sp. (Syrphidae:Diptera)
Brightly coloured flies
Body is striped or banded with yellow or blue
Resemble bees and wasps
Larval stage predatory, adults are pollinators
Crops pollinated - carrot, cotton, pulses
3.Carpenter bee, Xylocopa sp. (Xylocopinae:Anthophoridae)
, Robust dark bluish bees with hairy body
Dorsum of abdomen bare, pollen basket absent
Adults are good pollinators
Construct galleries in wood and store honey and pollen
4. Digger bees, Anthophora sp. (Anthophoridae:Hymenoptera)
Stout, hairy, pollen collecting bees
Abdomen with black and blue bands
5. Fig wasp Blastophaga psenes (Agaonitae:Hymenoptera)
Fig is pollinated by fig wasp only. There is no other mode of pollination.
There are two types of fig Caprifig and Symrna fig.
(i) Caprifig
a. It is a wild type of fig - not edible
b. Has both male and female flowers
c. Pollen is produced in plenty
d. Natural host of fig wasp
(ii) Smyrnafig
a. It is the cultivated type of fig - Edible
b. It has only female flowers
c. Pollen not produced
d. Not the natural host of fig wasp
Fig wasp: Male - wingless, present in caprifig
Female - winged
wasp lays eggs in caprifig, larvae develops in galls in the base of the flowers
mates with female even when the is inside gall
Mated wasp emerges out of flower (caprifig) with lot of pollen dusted around its
body.
The fig wasp enters smyrna fig with lot of pollen and deposits it on the stigma
But it cannot oviposit in the ovary of symrna fig which is deep seated
It again moves to capri fig for egg laying. In this process smyrna fig is pollinated
Caprifig will be planted next to smyrna fig to aid in pollination
6. Oil palm pollinating weevil: Elacidobins kamerunicus (Curculionidae :
Coleoptera)
Aid in increasing oil palm bunch weight by 35% and oil content by 20%
7. Other pollinators
