This document discusses biorational insecticides, which are pesticides derived from biological or natural origins that have limited adverse environmental effects. It defines biorational pesticides and provides examples of their benefits over conventional insecticides. The main types of biorational pesticides are then summarized, including those from plants, animals, microorganisms, insect growth regulators, and semiochemicals. Specific examples like neem, pyrethrum, Bacillus thuringiensis, entomopathogenic fungi and nematodes are then discussed in more detail regarding their origin, active ingredients, and mode of action.

2. BY
P.MANIKANDAN
Ist M.Sc(AGRI)ENTOMOLOGY
Chairman:Dr.R.Kannan
Annamalaiuniversity

3.  Biorational Insecticides
An active ingredient or formulation that
effectively controls pests and is derived
from biological or natural origins.
 What is a biorational pesticide?
These terms are derived from two words,
biological and rational, referring to
pesticides of natural origin that have limited
or no adverse effects on the environment or
beneficial organisms

4.  Better control than conventional insecticides
 Broader spectrum of activity
 Minimal effect on beneficial insects
 Short pre-harvest interval

5.  Cheaper
 Required for certified organic production
 Less toxic to workers or consumers
 Low phytotoxicity
 Safer for the environment
 Fast action and breakdown so low environmental
impact;

6.  Naturally occurring substances;
 Substances of plant origin (botanicals);
 Substances of animal origin;
 Microorganisms-based bio-pesticides;
Insect growth regulators;
Semiochemicals.

7.  Plants oils: Mint, pine and caraway (Carum carvi )
linseed, hempseed, cottonseed, rapeseed (colza), castor
bean (Ricinus communis), coconut, soybean, palm, corn...
 Substances of animal origin: beeswax, gelatine,
hyrolysed proteins…
 Animal fats: Whale, fish (cod, herring, menhaden,
sardine), degras (wool grease), lard, neatsfoot…
 Substances used in traps and/or dispensers:
Diammonium phosphate, metaldehyde, pheromones,
pyrethroids (Deltamethrin and Lambda-Cyhalothrin)
 Others: Paraffin and mineral oils, K-permanganate

8. Algae, 1
2%
Plants, 36
62%
Crustaceans,
1
2%
Microorga-nisms,
20
34%

9.  Source: Neem tree, Azadirachta indica ;
 Family: Meliacae;
 Natural Habitat : South Asia, in particular
India
 Extracted from seeds (Kernels);

10. Principal active ingredients: Azadirachtin A
(AZA) (C35H44O16) with its 7 isomers and
Azadirachtin B ;
 Mechanism of action: repellent,
growth regulator, anti-oviposition,
reduces adults fecundity and
eggs vitality.
 Mode of action: Contact, ingestion with a systemic activity;
 Activity spectrum: Effective against at lesat 200 insect
species, nematicide, acaricide with a certain fungicidal
activity.
 Pre-harvest interval: 3 days;

11.  Plants : Derris elliptica , mistica and malaccensis;
 Lonchocarpus utilis, urucu, nicou and chrysophyllus;
 Tephrosia macropoda, toxicaria, vogelii and virginiana;
 Family: Leguminosae;
 Extracted from roots;
Derris elliptica

12.  Plant: Tanacetum cinerariaefolium (Chrysanthemum)
and T. cineum.
 Family: Compositae;
 Natural habitat: China, east of Africa and Japan;
 Extracted from flowers;
 Main active ingredient: Pyrethrin I;
 Mode of action: Contact and ingestion;
 Mechanism of action: Acts on peripherical and central
nervous system causing an immediate insects paralysis;

13. Semiochemicals: Reppelents, attractants and
sex, alarm, and aggregation pheromones.

14.  Males locate and subsequently mate with females by following
the trail or pheromone emitted by virgin females.
 The indiscriminate application of high levels of sex
pheromone in traps and dispensers interferes with this natural
process since a constant exposure to high levels of pheromone
makes trail following impossible (habituation/adaptation
phenomenon).
 The use of discrete source of sex pheromone released over
time presents the male a false trail to follow (sexual
confusion/ mating disruption).
 Control is subsequently achieved through the prevention of
mating and consequently the laying of fertile eggs.
 Sex pheromone are species-specific.

15.  Alarm pheromones are released under natural
conditions when the population in threatened or being
attacked by a predator.
 The result of this release in an increase in the activity
of phytophagous insects with the subsequent higher
exposure to a co-applied pesticide.
 Alarm pheromones are often mixed with conventional
pesticides (especially acaricide) and show an increase
in the mortality of pests (mites).
 The alarmed pests (e.g. spider mites) feed less than
undisturbed ones.

16.  Repellent pheromones are emitted naturally by some
insect pests (e.g. beetles) when they reach a critical
density in order to repel additional insects and, thereby
to protect the food supply needed by these insects and
their offspring.
 A slight chemical alteration can change an attractant to
a repellent (e.g., Seudenol which is an attractant of
douglas fir and spruce beetles was transformed into 3-
methyl-cyclohex-2-en-1-one which is a repellent of the
same species).
 The use of repellent pheromone on healthy trees can be
combined with the use of aggregation pheromone on
dead or dying trees.

17.  Bacteria
 Fungi
 Viruses
 Nematodes
 Protozoa

18.  Viral diseases have been found in 13 insect orders and
most likely occur in all orders. Viruses that are
primarily or exclusively found in insects are currently
placed in 12 families (Miller, 1998):
 DNA Viruses: Baculoviruses (Nuclear polyhedrosis
viruses- NPV and Granuloviruses-GV), Ascoviruses,
Iridoviruses, Parvoviruses, Polydnaviruses and
Poxviruses.
 RNA Viruses: Reoviruses (Cytoplasmic polyhedrosis
viruses), Nodaviruses, Picorna-like viruses and
Tetraviruses.

19.  Out of above groups only 3 are safe:
-Nuclear Polyhedrosis Virus (NPV)
-Granulosis virus (GV)
-Cytoplasmic Polyhedrosis Virus (CPV)
 Species Specific
 Need to be ingested

20.  They can be divided into two broad
categories, non-spore-forming bacteria and
spore-forming bacteria.
 Although most of the species isolated from
diseased insects are non-spore-forming,
spore-forming bacteria in the genus Bacillus
are the most important from the standpoint
of biological control.
 Bacillus thuringiensis (Bt) spores can be
formulated as dusts or sprays and have been
used for years as “natural” insecticides.
About 100 different Cry proteins have been
identified and all have some specificity.

21. Out of all, Bacillus thurigiensis is the most used
 1921: reported in
Japan.
 1940s: Commercial
prep. Available in
France
 39% of
biopesticides
 Lep, Dip and Colep
strains
Crystals containing poison

22.  Entomopathogenic fungi are able to invade their insect hosts by
penetrating directly through the cuticle.
 The fungal spore first adheres to the cuticle.
 Under appropriate conditions the spore germinates, penetrates
the cuticle of the host and enters the hemocoel.
 Fungal reproduction occurs in the hemocoel of the insect host.
 As the hemocoel becomes filled with hyphal bodies, the insect
usually dies and the fungus continues to develop saprophytically.
 After the body of the dead insect is filled with mycelia, fruiting
structures emerge from the cadaver and produce infectious
spores.
 Dead insect has the consistency of a moist loaf of bread and,
depending on the colour of the spores or conidia, may appear
white or some darker colour.

23.  Tanada and Kaya (1993) listed 8 classes, 13
orders and 57 genera that contain
entomopathogenic species of fungi.
 There are five major groups of fungi: the
Flagellate fungi or Chytridiomycetes, the
Oomycetes (also flagellate but also not true
fungi), the Zygomycetes, the Ascomycetes,
and the Basidiomycota.
 The Zygomycota and the Ascomycota contain
common insect pathogens that are also
useful in biological control programs.

24.  Can penetrate cuticle

25.  Although nematode species in at least 20 families are
primary or facultative parasites of insects, those in the
order Rhabditida have been most exploited as biological
control agents.
 Species in the genera Steinernema and Heterorhabditis
(Steinernematidae and Heterorhabditae, respectively), are
particularly amenable to mass production and application in
a variety of pest systems.
 Entomopathogenic nematodes enter the host via natural
body openings or through the cuticle.
 Some species utilize an anterior stylet or a tooth to rasp the
cuticle and gain entrance into the hemocoel.
 Others ingress by ovipositing on the host food source and
the eggs hatch in the host midgut.
 Effects of nematode parasitism on the hosts can be sterility,
reduced fecundity, reduced mobility and life span,
behavioural and morphological changes, and death.

26.  Three important families:
- Steinenermatidae
- Heterorhabditidae
- Mermithidae
 Useful for soil and bark
insects

27.  Insect Growth Regulators (IGR) three main
types
Juvenile Hormones
Precocenes
Chitin Synthesis Inhibitors
 Low toxicity for birds, mammals, reptiles but
effects non-target arthropods and insects.
 Only immature pests are killed, IGR can also
effect arthropod eggs and embryogenesis.

28.  Insect Growth Regulators (IGR)
JH disruptor analogs - novaluron
Precocenes – methoprene, pyriproxyfen
Chitin Synthesis Inhibitors - cyromazine,
diflubenzuron

29. Though we know the potentiality of
biorational pesticides, we are still
utilizing the commercial insecticides
formulation, which leads to many pest
resurgence and resistance development.
Biorational formulations are helping to
overcome all these problem together
even it too have some limitations.
This field needs further research and lots
of resources to be spend in this sector to
make it further stable and sustainable as
well as farmers awareness towards this.

30. THANKYOU