MSc

The study entitled “Pests of curry leaf Murraya koenigii (L.) Spreng. and their
management” was carried out at the Department of Agricultural Entomology during the
period 2020-2022. The main objectives of the study were to document the pests
infesting M. koenigii, natural enemies associated with the pests, biology of major pests,
their nature of damage and symptoms, and to develop effective management practices.
The documentation conducted at twenty homesteads of Thiruvananthapuram
district for a period of one year, recorded twenty pests. The pests found infesting curry
leaf were lemon butterflies (Papilio demoleus Linnaeus and Papilio polytes Linnaeus),
citrus psyllid (Diaphorina citri Kuwayama), citrus green mite (Schizotetranychus
baltazari Rimando), curry leaf tortoise beetle (Silana farinosa (Boheman)), citrus leaf
roller (Psorosticha zizyphi (Stainton)), black looper (Hyposidra talaca (Walker)),
mealybug (Rastrococcus iceryoides (Green)), scale insects (Pinnaspis strachani
(Cooley) and Icerya aegyptiaca (Douglas), blackflies (Aleurocanthus terminaliae
Dubey & Sundararaj, Aleurolobus orientalis David & Jesudasan)), whitefly
(Aleuroclava complex Singh), hairy caterpillar (Olene mendosa Hübner), tortoise beetle
(Cassida exilis Boheman), ash weevil (Myllocerus brevirostris Marshall), bean bug
(Riptortus pedestris (Fabricius), coreid bug (Dasynus antennatus Kirby), leafhopper
(Empoasca sp.), bagworms (unidentified), cow bug (unidentified), slug caterpillar
(unidentified) and planthopper (unidentified). Out of the documented pests, H. talaca,
P. strachani, I. aegyptiaca, A. terminaliae, A. orientalis, Empoasca sp., C. exilis and
M. brevirostris were reported for the first time from Kerala as pest of curry leaves.
A total of eight spiders, one praying mantid, a reduviid bug, two predatory ants,
three coccinellids and three parasitoids were recorded. Spiders documented were
Burmese lynx spider (Oxyopes birmanicus Thorell), lynx spider (Oxyopes javanus
Thorell), white lynx spider (Oxyopes shweta Tikader), two-striped jumping spider
(Telamonia dimidiata (Simon)), wasp-mimic jumping spider (Rhene flavicomans
(Simon)), crab spider (Camaricus formosus Thorell), jumping spider (Carrhotus sp.)
and heavy-bodied jumper spider (Hyllus semicupreus (Simon)). Praying mantid
(Odontomantis pulchra Olivier), reduviid bug (Scipinia horrida (Stål)), ants
(Camponotus compressus (Fabricius) and Diacamma ceylonense Emery), and three
coccinellid beetles of the genus Phrynocaria sp. were also recorded. Parasitoids
obtained were larval parasitoid (Tachinidae) from P. polytes, nymphal parasitoid
Tamarixia radiata (Waterson) from D. citri nymphs and pupal parasitoid Brachymeria
apicicornis (Cameron) from S. farinosa. A consolidated documentation of spiders and
other defenders from curry leaf is first of its kind from Kerala.
Biology studies were carried out for S. farinosa, D. citri, and P. polytes under
laboratory conditions. P. polytes had a mean number of days of 3.30 + 0.15, 20.30 +
0.26 and 8.40 + 0.16 as egg, larval and pupal period, respectively. S. farinosa had a
mean of 5.30 + 0.15, 16.80 + 0.29, 5.00 + 0.21 and 81.10 + 0.80 days as egg, grub,
pupal and adult period, respectively. D. citri had a mean of 3.50 + 0.15, 12.50 + 0.41
and 25.75 + 0.66 days egg, nymphal and adult period, respectively.
To evaluate the qualitative damage due to pest infestation, chlorophyll,
carotenoids, ascorbic acid, and tannins in mite infested (broad, narrow leaved) and
psyllid infested (broad leaved) leaves were compared with their quantity in uninfested
broad and narrow leaved samples. Murraya exotica, a closely related species of M.
koenigii was found resistant to most of the pest species recorded from the latter. Hence,
a comparative study of its biochemical constituents was also done. Results showed a
decline in chlorophyll content by 13.64 and 63.16 per cent in mite infested broad and
narrow leaved samples, over their respective control and a reduction of 36.36 per cent
in psyllid infested samples. In psyllid infested broad leaved samples, carotenoid content
got reduced by 18.00 per cent over its uninfested control whereas a reduction of 28.96
per cent occurred in mite infested narrow leaved samples over its respective control.
Quantity of ascorbic acid also declined by 30 per cent in mite infested broad leaved
sample whereas other samples showed no significant reduction. Tannin content
increased by 6.51 and 20.20 per cent in mite and psyllid infested broad leaved samples,
respectively over uninfested samples whereas it showed a reduction of 13.60 per cent
in mite infested narrow leaved sample. M. exotica showed a decrease in chlorophyll,
carotenoids and tannin content by 31.82, 16.85 and 5.88 per cent, respectively and an
increase in ascorbic acid content by 42.68 per cent over uninfested M. koenigii.
A field experiment conducted at farmer’s field for evaluating effective
management practices against curry leaf pests revealed that among biopesticides, neem
garlic soap formulation- KAU Raksha @ 10 g L-1
and talc based formulation of L.
lecanii NBAIR Vl 8 @ 20 g L-1 were effective in reducing the population of psyllids
by 65 and 58.17 per cent and damage by 51.48 and 60.53 per cent, respectively 14 DAT.
Against mites, Horticultural Mineral Oil HMO @ 25 mL L-1
and talc based formulation
of L. lecanii NBAIR Vl 8 @ 20 g L
-1 were effective in reducing the population by 39.18
and 33.44 per cent and damage by 35.74 and 42.37 per cent, respectively. Whitefly was
effectively managed by talc based formulation of L. lecanii NBAIR Vl 8 @ 20 g L-1
which reduced the population and damage of whitefly by 75.23 and 63.23 per cent,
respectively 14 DAT. The chemical insecticide, chlorantraniliprole 8.8 % w/w +
thiamethoxam 17.5 % w/w SC @ 150 g a.i ha-1 was effective in reducing psyllid, mite
and whitefly population by 89.91, 49.76 and 76.63 per cent and damage by 79.08, 55.57
and 81.04 per cent, respectively over untreated control, 14 DAT. All chemical
treatments were toxic to spiders and caused cent per cent reduction of spiders, 14 DAT.
Harvest time residue analysis showed that, the residues of all the three insecticides viz.,
chlorantraniliprole, thiamethoxam and quinalphos were below the limit of
quantification, at 14 DAT.
The present investigation documented twenty pests, fifteen predators and three
parasitoids from curry leaf ecosystem. Based on the extent of incidence, D. citri, P.
polytes, S. baltazari, and S. farinosa are categorised as major pests. The biochemical
analysis proved the qualitative deterioration due to pest damage, which emphasise the
importance of developing good agriculture practice in curry leaf pest management as it
is an important raw material in ayurvedic medicinal preparations. For managing pests
infesting curry leaves, talc based formulation of L. lecanii NBAIR Vl 8 @ 20 g L-1
,
neem garlic soap formulation-KAU Raksha @ 10 g L-1
or Horticultural Mineral Oil
HMO @ 25 mL L-1
can be recommended as non-chemical options whereas the
insecticide chlorantraniliprole 8.8 % w/w + thiamethoxam 17.5 % w/w SC @ 150 g a.i
ha-1
can be recommended for managing severe pest infestation.