The document discusses natural enemies and the sublethal effects of insecticides on them. It begins by defining key terms like sublethal dose, insecticide, natural enemy, pest, integrated pest management, chemical control and biological control. It then provides tables listing important natural enemies and parasitoids of crop pests. The document discusses the physiological and behavioral effects insecticides can have at sublethal doses, including effects on development, fertility, mobility and orientation. It explains the mechanisms of insecticide penetration in insect bodies and their modes of action.

1. DEPARTMENT OF ENTOMOLOGY, CO-A, RAIPUR
Indira GandhiKrishi Vishwavidyalaya
By,
SAURABH
PADAMSHALI
Ph.D. Scholar

2. • Dose or concentration of a potentially lethal substance
inducing no apparent mortality in the experimental
population, i.e., not large enough or sufficient to cause
death.
Sub-lethal
dose
• An insecticide is a substance of chemical,
plant or microbial origin used to
kill insects.
Insecticide
• Natural enemies (predators, parasites &
parasitoids) are organisms that kill, decrease the
reproductive potential of, or otherwise reduce
the numbers of pest species.
Natural
enemy
• An organism which is troublesome /destructive
and whose activities causes loss or annoyance
and is inimical to welfare of human being or his
property to the extend that warrants its control.
Pest

3. *The integration of chemical and biological control is often critical to
the success of an integrated pest management (IPM) program for
insect-pests of agricultural crops (Volkmar et al. 2008).
*Aim of studies on the sublethal effects of insecticides on natural enemies
is,
Integrated
Pest
Management
Chemical
control
Biological
control
 To assess the suitability of
insecticides for IPM.
 To reduce non-target effects of
insecticides on natural enemies,
 To test & select insecticides with
a minimal non-target lethal
toxicity.

4. NATURAL ENEMIES
 Are essential pest control agents,
 Interact with their hosts in a cyclical homeostasis
 Prevents many plant-feeding insects from becoming economic pests
ADVANTAGES :-
• High searching capacity,
• Host specificity,
• Potential rate of increase,
• Widely distributed,
• Adapted to broad range of climatic conditions,
• Suitable for lab culture.

5. s.
No.
NATURAL ENEMY FAMILY CROP PESTS
1 Rodolia cardinalis Coccinellidae
Coleoptera
Cottony cushion scale (Icerya purchasi)
2 Cryptolaemus montrouzieri Coccinellida
Coleoptera
Mealy bugs and scale insects
3 Paederus fuscipes
(Rove beetle)
Staphylinidae
Coleoptera
Mites, dipteran larvae,lepidopteran
eggs,larvae & pupae,leaf and plant
hoppers
4 Ophionia indica Carabidae
Coleoptera
Eggs & larvae of lepidoptera,leaf and
plant hoppers, other small insects
5 Phoropsophus sp. Carabidae
Coleoptera
Grubs of rhinoceros beetle
6 Chrysoperla carnea
(Green lace wing) Neuroptera
Aphids, white flies, lepidopteran eggs&
larvae
7 Hemerobius sp.
(Brown lace wing)
Hemerobiidae
Neuroptera
Aphids,mealy bugs, white flies, adelgids
8 Rhynocoris fuscipes
(Assassian bug)
Reduviidae
Hemiptera
H. armigera larvae
Aphids, leaf-hoppers, larvae & adult
beetles
IMPORTANT PREDATORS OF SOME CROP
PESTS

6. s.
No.
NATURAL ENEMY FAMILY CROP PESTS
9 Platymeris laevicollis Reduviidae
Hemiptera
Rhinoceros beetle
Aphids, leaf-hoppers, larvae & adult beetles
10 Anthocoris sp. Anthocoridae
Hemiptera
Adelgids ,aphids, soft bodied insects, insect
eggs & mites
11 Orius sp. Anthocoridae
Hemiptera
H. Armigera
12 Cyrtorhinus lividipennis Miridae
Hemiptera
Eggs & early instar nymphs of leaf & plant
hoppers, leaf roller
13 Deraecoris sp. Miridae
Hemiptera
Aphids
14 Geocoris sp. Lygaeidae
Hemiptera
Aphids, mealy bugs, leafhoppers, eggs & small
caterpillars & grubs, spider mites
15 Hover flies
(Episyrphus balteatus, Metasyrphus
sp.)
Syrphiidae
Dipteral
Aphids & adelgids
16 Leucopis sp. Chamaemyiidae Aphids, mealy bugs,soft scales

7. S.N
O.
NATURAL ENEMY FAMILY &
ORDER
CROP PEST
1 Epiricania
melanoleuca
Lycaenidae
Lepidoptera
Ectoparasitoid of sugarcane leaf hopper ,scales, mealy
bugs, aphids
2 Trichogramma sp. Trichogrammatida
e
Hymenoptera
Egg parasitoid of different lepidopteran, coleopteran,
dipteran, hemipteran & hymenopteran pests
3 Telenomous sp. Scelionidae
Hymenoptera
Egg parasitoid of lepidopteran, coleopteran, dipteran,
hemipteran & hymenopteran pests
4 Anagrus sp. Mymaridae
Hymenoptera
Egg parasitoid of different lepidopteran, coleopteran, dipteran,
hemipteran pests especially leaf & plant hoppers
5 Bracon sp. Braconidae
Hymenoptera
Gregarious larval ecto-parasitoid of lepidopteran pests
6 Cotesia plutella Braconidae
Hymenoptera
Solitory larval endo-parasitoid of DBM
7 Apanteles sp. Braconidae
Hymenoptera
Solitory larval endo-parasitoid of P. gossypiella
8 Campoletis chloridae Ichneumonidae
Hymenoptera
Larval parasitoid of H. armigera
9 Gonozius
nephantidis
Bethlidae
Hymenoptera
Gregarious ecto-larval parasitoid of Opisina arenosella
10 Sturmiopsis inferens Tachinidae
Diptera
Larval parasites of sugarcane borer
IMPORTANT PARASITOIDES OF SOME CROP
PESTS

8. • Neurotoxic insecticides are the main cause of insect mortality.
• The main groups of insecticides that act on the nervous system and the
mechanisms involved are :-
INSECTICIDES
S.NO. CHEMICAL SUB-GROUP MAIN GROUP & PRIMARY SITE OF ACTION
1 Organophosphates & carbamates Acetyl choline estrase inhibitors
2 Cyclodienes, organochlorines,
phenylpyrazoles
GABA-gated chloride channel antagonists
3 Pyrethroids & DDT Sodium channel modulator
4 Neonicotinoids Nicotinic acetyl choline receptor agonists
5 Spinosyns Nicotinic acetyl choline receptor allosteric
activators
6 Avermectines Chloride channel activators
7 Azadirachtin Ecdysone agonists
8 Indoxacarb Voltage dependant sodium channel blockers

9. Mechanism Of Insecticide Penetration
In Insect Body
STEP 1
• Predators and parasitoids may get in touch with insecticides via host, direct
contact or by the ingestion of nectar and pollen in flowers
STEP 2
• penetrating the cells
STEP 3
• Crossing barriers: first, the membranes that surround any animal cell and
secondly, the whole tissue
STEP 4
• reach the modes of transport (blood stream) and spread in the organism
STEP5
• block some physiological or biochemical process ,mainly nervous system
STEP 6
• produce impacts on the survival, growth, development, reproduction and
behavior of organisms

10. Sublethal Effects Of Insecticides On Natural
Enemies*Sublethal effects are effects (either physiological or behavioral) on
individuals that survive exposure to a insecticide (the insecticide
dose/concentration can be sublethal or lethal).
SUBLETHAL EFFECTS
BEHAVIORAL
EFFECTS
Mobility
Navigation/orientation
Exposure
Sexual communication & mate finding
Feeding behavior
Oviposition behavior
Learning performance
PHYSIOLOGICAL
EFFECTS
General biochemistry & neurophysiology
Malormations
Fertility
Fecundity
Adult emergence
Developmental rate
Adult longevity
Growth & development
Mortality
Sex-ratio

11. PHYSIOLOGICAL EFFECTS :
EFFECT ON GENERAL BIOCHEMISTRY AND
NEUROPHYSIOLOGY
*The inhibition of AChE lead to disturbance in all systems because it is a
major component in all synaptic transmission , especially when inhibition
continues for a long time after exposure.
* Sublethal effects on larval development may result from disturbance in
development of neural tissues by neurotoxic substances.
*IGRs are commercial hormone mimics that disrupt molting (juvenile
hormone or ecdysone mimics) and cuticle formation (chitin inhibitors) and
more generally act on endocrine systems.
Treatment with
imidachloprid
Increase of CO
activity in the
brain
Physiological
effect at the
level of the
mushroom body
Impairment of
olfactory
memory
IGRs
Produce changes in
metamorphosis hormones
disrupt molting &
cuticle formation

12. •Abnormalities in the alimentary canal were due to,
lysis of intercellular cementing material,
pycnotic nuclei,
vacuolated cells,
 obliteration of the peritrophic membrane and
exfoliation of cells.
•Sublethal dose of insecticides causes,
 predator size reduction,
sperm cell distortion,
vacuolated spermatocytes in the testis,
crumpled follicular epithelium and
 vacuolization of the germarium in the ovaries and
Malformation of ovaries (can also occur in parasitoids exposed to IGRs)
GROWTH ABNORMALITIES

13. EFFECT ON FERTILITY
* Accor. to Desneux et al. 2007,sublethal dose of insecticide
causes,
 decrease in fertility or infertility in
adults,
 reduction in period of fertility,
 delays copulation,
 production of infertile eggs,
 influence the dynamics of
populations.

14. EFFECT ON FECUNDITY
* Insecticides link to the ecdysteroid receptors, causing
 Disturbance in processes of vitellogenesis,
 Decreased growth in spermatocyte
 Reduction in ovulation of mature egg,
 Repellence of oviposition,
 Reduction in number of eggs and
 Reduction in viable eggs .

15. Effect On Rate Of Development
*Developmental rate can have a large impact on a natural enemy’s
• intrinsic rate of increase (rm) and
• phenological synchrony with the host or prey.
* An increase in developmental rate could disrupts synchrony with susceptibility
in the host.
*Fenoxycarb prolong the development time Chrysoperla rufilabris.
*Trichogramma pretiosum pupae display higher sensitivity
*The impact of insecticides on development time may also be a function of gender.
Supputius
cincticeps
Exposure to
permethrin
Development
time
Decreases for
females
Increased for
males.

16. EFFECT ON ADULT EMERGENCE
*Studies using parasitoids often report effects like difficulty
in adult emergence from the pupal stage.
*Mallada signatus azadirachtin A (AzaA) in the pupal stage.
*A decrease in emergence from parasitized host after exposure to
Hyposoter didymator spinosad (spinosyns)
*Similarly in, Chrysoperla carnea fenoxycarb (juvenile hormone analog)

17. EFFECT ON ADULT LONGEVITY
*Main factors for the reduction of
longevity
•infertility caused by sublethal dose of
insecticides,
•biology of the natural enemy
[pro-ovigenic or syn-ovigenic,
parasitoid or predator],
•amount of feeding and reproduction
between exposure & death.

18. EFFECT ON GROWTH AND
DEVELOPMENT*Impacts differs with the biology of the experimental subject (i.e.,
predators Vs parasitoids). It causes,
Prolonged the time of development
Chysoperla rufilabris in all stages fenoxycarb
A prolonged development stage has been reported with the use of
neurotoxic insecticides in predators
botanical insecticides in parasitoids
Higher sensitivity in pupae of T. pretiosum
Decrease in parasitism and predation performance due to effects
related to malformation during the development phase.

19. EFFECT ON MORTALITY
*High mortality
In Vespidae, Polybia paulista and P. exigua chlorpyrifos
* Reduced survival
33%mortality larvae of Coccinella undecimpunctata buprofezin,
>61% mortality in Encarsia sp. cartap, imidacloprid, malathion,
metamidophos, acephate, acetamiprid

20. EFFECT ON SEX - RATIO
*Different males and females differences in their physiology
*The asymmetrical mortality of males and females alters the
sexual ratio
*Two major causes altering the sex-ratio of the offspring when adults
are exposed to insecticides are,
•an effect on the fertilization of ova, especially in haplo-diploid
species in which the fertilization of ova is a voluntary act by
females when they are laying eggs, and
•differential survival of sexes when exposure is before the adult
stage
*Additional effects may be due to deformations of ovaries and testes.
*Age of the females may be important to determine the sexual ratio

21. II. BEHAVIORAL EFFECTS
*Sub-lethal effect of insecticides on behavior is a syndrome that
affects,
• motility,
• orientation,
• feeding,
• oviposition and
• learning.
*In many cases, insecticides act as repellents that are associated to
the behavior of food searching.
*In some cases, repellence is the result of the contact with the host
or prey treated with insecticides. Which results into parasitoid
oviposition reduction or acceptance of the prey by the predator.

22. EFFECT ON MOBILITY
Effects on the mobility of natural enemies are mostly due to,
* direct intoxication by the insecticides,
• resulting in knock-down effect,
• uncoordinated movement ,
• trembling,
• tumbling,
• abdomen tucking or rotating and
• cleaning of the abdomen while rubbing the hind legs together.
* secondary consequences of behavioral modifications such as,
• disruption in the detection of kairomones that result in an increase of
angular speed due to higher arrestment by kairomone patches and
• hydrous stress; and
• a repellent or irritant effect of insecticides .

23. Sensorial
system
Captures
stimuli
Visual
system
Olfactory
system
the chemical
perception of
the
substances
used to
attract or
repel
habitat
localization,
light
perception
perceptions
of form and
size of
objects
Navigation & orientation
Activity & capacity of guiding
in environment with
accuracy
*Involves multiple sensory cues, either chemical
or visual.
*Depends entirely on nervous transmissions,
which are targeted by neurotoxic insecticides
through different modes of action.
*Reduction in the capacity of guiding themselves
to the host plants ,
Parasitoids Lambdacyhalothrin & carbamates
*Reduced flying activity ,
Females of Microplitis croceipes fenvalerate &methomyl,
*Reduced capacity of finding and capturing preys.
Predators cypermethrin
EFFECT ON
NAVIGATION/ORIENTATION

24. EFFECT ON SEXUAL COMMUNICATION AND MATE-
FINDING*Insecticides disrupts chemical communication
between sexual partners by altering the capacity for
• stimulus creation by the emitter or
• stimulus perception by the receiver.
*Stimulus detection and integration by the CNS are
potential targets for perturbations.
T. brassicae
males
exposed to a LD0.1 of
chlorpyrifos
less arrested by female
sexual pheromones
LD 0.1 pyrethroid
deltamethrin
increase in arrestment
females
exposed to a LD0.1 of
chlorpyrifos
more arresting for
untreated males
LD 0.1 pyrethroid
deltamethrin
pheromones were less
arresting for males
Thrichogramma
brassicae
Low dose of
deltamethrin
males
did not respond to the signals of
females
females
reduced their capacity of attracting
untreated males

25. EFFECT ON FEEDING BEHAVIOR
Insecticides may interfere in three different ways in the feeding behavior,
1. repellent effect, which reduces the amount of food of these insects.
2. anti-food properties, which reduce the feeding stimulus
3. loss of the ability to find food soon after the exposition of the insecticides due to the
reduced olfactory capacity
An anti-feedant results into regurgitation response after consumption.
The process of food detection disrupted by neurotoxic insecticides, accompanied by a
reduction in food intake, haphazard movement, and signs of restlessness.
Reductions in the rate of consumption by the predators.
The decrease in parasitism capacity may result from reduced energy intake, as well as
from indirect effects on host detection.
Pro-ovigenic
Natural
Enemies
Reduced
Feeding
Reduced
Longevity
Influence
Parasitism/
Predation
Rate
Syn-ovigenic
Natural
Enemies
Reduced
Feeding
Reduced
fitness
Reduced Egg
Production

26. EFFECT ON OVIPOSITION
BEHAVIORReduced chances to find their hosts for oviposition
Change in the motor nerve coordination during the oviposition
Disruption of coordination between the insect nervous and hormonal
systems, resulting in a breakdown in series of events related to oviposition .
 An irreversible uncoordinated ovipositor
extrusion and consequently failure in egg
laying,
 Reduction in the number of ovipositor
insertions into a host, host mine drumming
frequency, and the number of eggs laid,
 Effects on oviposition were formulation
dependent
DUST WETTABLE
POWDER
SOLUBLE
CONCENTRATES
EMULSIFIED
CONCENTRATE
GRANULES

27. IMPACT OF SUBLETHAL EFFECTS
ON COMMUNITY ECOLOGY
*Sublethal effects of insecticides interacts with
numerous life-history traits involved in the reproduction of
natural enemies such as,
* Foraging,
* Fecundity,
* Sexual communication, and
* Sex ratio.
*Insecticides tend to lower the abundance of both parasitoids and
their hosts, and
*Lead to the disappearance of scarce species (species that are not
naturally abundant in a given agroecosystem)

28. CONSEQUENCES OF DISRUPTING
BIOLOGICAL CONTROL
The decrease in the number of natural enemies
caused by the use of non-selective insecticides
results in,
*Pest resurgance
*Secondary pest outbreak
*Pesticide resistence

29. PEST RESURGANCE
When resurgence occurs, the pest reappears in subsequent
harvests, come from places of refuge and individuals that survived
in the crop, in population levels higher than that of the previous
harvest.

30. SECONDARY PEST OUTBREAK
The eruption of pests is the change of the pest status, from
secondary pest to key pest, especially due to the reduction of the
natural enemies that keep pests below the level of economic loss

31. Pest population can develop resistence to insecticides through natural selection
• When insecticides are applied,most individuals are killed but a few are less susceptible and
these remain.
• The less susceptible individuals or their progeny are less likely to die with subsequent
applications.
• After repeated applications,the resistent or less susceptible individuals predominate and the
same insecticide is no longer effective.(Flint & Dreistadt, 1998)
INSECTICIDE
RESISTENCE

32. Techniques to Reduce the Negative Impact of
Sublethal Effects Of Insecticides on Natural Enemies
A. Crop monitoring and economic thresolds
1) Apply only when necessary, and use reduced dose for application,
2) Knowledge of the impact of pest species on the commodity in
question
3) monitoring the pest to determine when it may cause problems
4) An understanding of the effectiveness of natural enemies is
essential to avoid applying pesticides when biological control is
adequate
5) The impact of treatments on natural enemies of secondary pests
should also be considered when decisions are made to treat for
primary pests.
6) Choose a product that is efficient to pests and selective to natural
enemies.

33. PESTICIDE SELECTIVITY
*The capacity of a pesticide treatment to spare natural enemies while
destroying the target pest.
Pesticide Selectivity
Ecological Selectivity Physiological Selectivity
based on the mechanism by which a pesticide
treatment is preferentially toxic to pests Vs
their natural enemies

34. Physiological selectivity
* Is physiological differences in susceptibilities of pests and
associated natural enemies to a pesticide.
*Effective use of physiologically selective compounds to enhance
biological control is dependent on factors like,
• The type of pests (primary, secondary) targeted for control
• Relative levels of pesticide resistance in non-targeted pest species.
• manipulate the natural enemy / pest ratio to favour the
natural enemies by differential mortality of the pest.Pest Resurgence
• (and the primary pest lacks effective natural enemies)
survival of the primary pest after treatment is less
important than for a potential resurgence problem.
Secondary Pest
Outbreaks
• use compounds with high specificity to control the
primary pest.Insecticide Resistance

35. Ecological selectivity
 Results from differential exposure of pests and natural enemies to a
pesticide.
Includes,
Modification of the pesticide
Reduction of application rates
Use of Non-persistent pesticides
Modification of application methods
Modification of application methods
Temporal discrimination
• application of pesticides when
pests are present and natural
enemies separate at any time
Habitat discrimination
• application of pesticides to
the parts of the habitat
where the pest is more
frequently found than the
natural enemy.
Habitat partitionment
• division of the targeted
area so that pesticides are
only applied to parts of the
area
• 1) Spot treatments
• 2) Crop partitioning

36. FUTURE PROSPECTS AND NEEDS
 The integration of biological and chemical controls.
 Increase public awareness of deleterious non-target effects of
Sublethal dose of insecticides,
 Compatibility with chemical control for the increased adoption of alternative
methods,
 Increasing temporal and spatial separation between insecticide treatments and
parasitoids, for their integration in pest management programs,
 The integration of physiological and behavioural sublethal effects of insecticides
may help in analysis of population fitness, specifically focused on the population
growth rate of the natural enemies, to manage insect pest populations for ipm
decision-making.
Methods to assess non-target effects on natural enemies & choice of indicator
species
Development of standardized methods assessing sublethal effects on key
components of natural enemy efficiency before incorporating these effects into
regulatory procedures.
To establish a link between the toxicity of a given product in laboratory assays and
the risk associated with exposure under field conditions.

37. CONCLUSION
There is great potential for increasing the benefits derived from naturally
occurring biological controls, through the elimination or reduction in the use of
insecticides toxic to natural enemies as the use of insecticides has brought
losses and negative impact on natural enemies. When these beneficial insects
reduce cause the eruption of pests and resurgence is more common. Thus
principles of conservation these natural enemies are extremely important in
the biological natural control of pests, so that these natural enemies may
present a high performance inspite of the negative impacts caused by
insecticides on agriculture and their harmful effects on natural enemies.
Still, complete insecticide replacement by non-
chemical methods is unlikely to happen in the near
future. Therefore, compatibility with chemical control is
essential for the increased adoption of alternative
methods, such as the integration of biological and
chemical controls.