Weed , history , Principles , key concepts , Aim , Fundamental of Biological Control , Types , Augmentive , Conservation , Classical , Mycoherbicides , Advantages , Limitations , Project in Biological Control , Prickly pear , Lantana camara , Water Fern-Salvinia molesta , Alligator weed-Alternanthera philoxeroides , Use of pathogen

1. Dr Yashwant Singh Parmar University of Horticulture and Forestry Nauni Solan(H.P.)
Biological Control of Weeds
Ajay Sharma
(Dept. of Entomology)

2. Introduction

3. Losses caused by weeds are-
Weed

4. Major milestones in history
Cochineal
mealybug
Dactylopius cqrlonicw

5. Commonwealth Prickly Pear Board
Cactoblastis cactorum
rust fungus,
skeleton weed,

6. Principles of Biological Weed Control
Crofton weed leaf affected by Crofton rust fungus

7. Biological control covers two key concepts:-

8. Aim of Biological control of weeds

9. Considerations of species for introducing pest to control
weeds

11. Fundamental of Biological Control of Weed

13. Types of biological control:
• Augmentive biological control-
• Adding natural enemies, either where they are not present, or are present in
small number.
• Inoculative biocontrol: Begin with a small number and allows the natural
enemy population to increase over time. In this case pest population does not
decrease quickly.
• Inundative biocontrol: Introduction of a large number of natural enemies,
with the intention of reducing the pest population quickly.

14. • Conservation control:

15. • Classical biocontrol:

16. Release of
Control Agents
Process of Weed control by Biological Agents

17. How does it work
stunt plant growth
release toxins
disrupt the water transport
reduces leaf growth.
feed directly
feed on leaves

18. severe infestations
bio herbicide

19. Mycoherbicides
Mycoherbicide Trade name Country Weed controlled
C. gloeosphoroides Collego USA Joint ventches
C. gloeosphoroides LUBOA2 China Cuscuta sp
Cercospora rodmanii ABG 5003 USA Eichhornia crassipes
C. gloeosphoroides Biomal USA Malva f. sp. malvae pusilla
Phytophthoro palmivora Devine USA Malva f. sp. malvae pusilla
Alternaria cassiae CASET USA Cassia obtusifolia

20. Advantages

21. Limitations

22. Project in Biological Control
of Weeds

23. Steps in a successful biological control of weeds
project
1.Initation
2. Approval to work
3.Foreign exploration
4.Survey the exotic range of the weed
5.Ecology of weed &natural enemies

24. 6.Host specificity studies
7.Approval of agents
8.Importation
9.Rearing & release
10.Evaluation
11.Distribution

25. Examples of successful classical biological control
(A) TerrestrialWeeds-
1. Prickly pear (Opuntia spp.)-

26. BEFORE
AFTER

27. 2. Lantana camara
seed fly
lace bug gall
fly two butterflies
Lace bug,Teleonemia scrupulosa
feeding on lantana
Lace bug

28. 3.Congress grass, Parthenium hysterophorus

29. 4. Crofton weed (Pamamkani), Ageratina adenophora (Eupatorium
adenophorum) DAMAGE
ADULT

30. • 5.Siam weed Chromolaena odorata
Pareuchaetes pseudoinsulata
adults and eggs on Siam weed

31. • (B) Aquatic Weeds-
1.Water hyacinth, Eichhornia crassipes
Hydrophilic weevils
Galumnid mite
BEFORE AFTER

32. 2.Water Fern, Salvinia molesta
BEFORE AFTER

33. 3.Alligator weed, Alternanthera philoxeroides
• Alligator weed flea- beetle
alligator weed moth

34. Use of pathogen in Weed suppression

35. References
• De Bach P. 1964.