TRITROPHIC INTERACTIONS IN INSECT PESTS OF RICE

1. TRITROPHIC INTERACTIONS IN INSECT PESTS OF
RICE
Presented by
N.Ramya sri
RAD/17-12

2. INSECT PESTS OF RICE

6. Tritrophic interactions

10.  Plants confront the herbivores
 Direct defenses
 Indirect defenses
 Direct defenses – affect the herbivore’s
biology and survival
 By mechanical protection- hairs, trichomes,
thorns, spines etc.
 By production of toxic chemicals —
secondary metabolites etc.
 Indirect defenses — blend of volatiles to
attract NE’s
 By providing food Extra Floral Nectar (EFN)
 By housing (Domatia) the natural enemies
10

11. Plant morphological traits affect tritrophic interaction:
In rice, trichome density, leaf length, leaf surface and leaf sheath
compactness are associated with food searching capability of rice
pests as well as natural enemies on rice genotype.
11

12. Islam and Karim (1997) who also observed that plants with
broader leaf width facilitate easy folding and provide more area
for feeding of leaffolder. Further, they also stated that the larvae
of leaf folder faced difficulty in making folds in narrower leaves
which probably afforded less protection from harsh weather and
natural enemy complex.
Shepard and Anda (1986) suggested that the higher incidence of
parasitism and predation of stem borer eggs in transplanted rice
was due to a more open canopy .

13. Secondary metabolites and plant defense:
 The secondary metabolites can be either
–Phytoanticipins (constitutive stored as inactive)
–Phytoalexins (induced by herbivore attack)
 Phytoanticipants includes glucosinolates
 Phytoalexins include phenolics, isoflvonoids, terpenoides etc.
13

15. • Volatile profiles of rice cultivars indicated the presence of 9,12,15
octadecatrienoic acid and 9-octadecenal, which may have played a
positive role in the attraction of T. chilonis to specific cultivars
while hexadecane, heptadecane, pentadecane and hexadecanoic acid
were reported to be responsible for the attraction of T. japonicum.
• High quantities of octadecanoic acid emitted from rice plants
damaged by yellow stemborer may play a pivotal role in attracting
Trichogramma spp. as well as in stimulating oviposition .
• Rice plants damaged by feeding of Spodoptera frugiperda (fall
armyworm, FAW) were shown to emit Indole that is highly
attractive to parasitic wasps ( Yuan et al, 2008).

16. • Natural enemies like Anagrus nilaparvatae and Anaphes iole were
reported to be attracted to rice infested with Nilaparvata lugens and
Lygus hesperus .Attraction was evident between 6 and 24 hr after
infestation by 10-20 adult females per plant
• Hu and Chen reported that spraying of kairaomones extracted from
the frass of Cnaphalocrocis medinalis (Guenee) (Lepidoptera:
Crambidae) on rice plants in the field increased by 15-25% the
parasitization of C. medinalis by Apanteles cypris Nixon
(Hymenoptera: Braconidae)
• silicon amendment may contribute to the suppression of C.
suppressalis directly through reduced feeding damage and
performance and indirectly through increased exposure time of
young larvae to natural enemies

17.  (E) – beta –caryophyllene in rice has been reported to be
attractive to BPH and their natural enemies.
Compatibility plant defenses with natural enemies:
The host plant resistance may enhance the predatory activity
which is favourable for biological control.
Predatory activity of mirid bug Cyrtorhinus lividipennis on
BPH was more on a resistant rice variety IR 36 than susceptible
variety IR 8

18. Chemical Cues In Tritrophic Interactions On
Biocontrol Of Insect Pest
• Volatiles extracted from egg-infested plants were used as
chemical cues by egg parasitoid to find its host.
• The volatiles compounds which mostly play an important role
in tritrophic interaction among host plant-herbivore-parasitoid
are long-chain hydrocarbon.
• Orientation behavior of parasitoids toward extract on BPH-
eggs infested plants in Y-tube olfactometry was higher
Nurindah., et al (2017)

20. Orientation behavior of parasitoids toward BPH-eggs infested
plants and extract on BPH-eggs infested plants in Y-tube
olfactometry
Source of
volatiles
Number of parasitoids showed
orientation behavior
R+ R- NR
Infested plant 21 c 9 b 0 a
Extract of infested
plant
22 c 1 a 7 b
R+: Parasitoids orientation showed positive response, R-:
Parasitoids orientation showed negative response, NR: Parasitoids
showed no response.

21. REFERENCES
• Abenes M L P, Khan Z R. 1990. Biology of rice leaffolders (LF) on
susceptible IR 36 and resistant TKM6. Int Rice Res Newsl, 15(3): 14.
• Chalapathi Rao N B V, Singh V S, Subhash C. 2002. Evaluation of rice
germplasm for resistance to rice leaffolder, Cnaphalocrocis medinalis. Ind
J Entomol, 64(2): 124–129.
• Courteney S P, Kibota T T. 1990. Mother doesn’t know best: Selection of
host by ovipositing insects. In: Berney E A. Insect-Plant Interactions.
Volume II. Florida: CRC, Boca Ration: 162–188.
• Dakshayani K, Bentur J S, Kalode M B. 1993. Nature of resistance in rice
varieties against leaffolder Cnaphalocrocis medinalis (Guenee). Insect Sci
Appl, 14(1): 107–114.
• Dale D. 1995. Insect pests of the rice plant: Their biology and ecology. In:
Heinrichs E A, Aguda R M. Biology and Management of Rice Insects.
India: Wiley Eastern & New Age: 363–485.

22. THANK YOU