MSc

A study on “Management of pests of cowpea and salad cucumber in
polyhouse” was undertaken in polyhouses of Thiruvananthapuram district and
College of Agriculture, Vellayani during January 2015 to May 2016. The main
objectives were to document the pests and natural enemies on cowpea and salad
cucumber in polyhouses and to evaluate the efficacy of new generation insecticides
against the major pests.
A purposive survey was conducted in 20 polyhouses in Thiruvananthapuram
district to document the pests and natural enemies. Sucking pests viz., pea aphid,
Aphis craccivora (Koch), mealy bug, Ferrisia virgata (Cockerell), pod bug, Riptortus
pedestris (Fabricius), fulgorid bug,
Eurybrachys tomentosa (Fabricius), thrips,
Ayyaria chaetophora (Karny), spotted red mite, Tetranychus truncatus (Ehara) and
leaf feeders viz., pod borer,
Lampides boeticus (Linnaeus), tobacco caterpillar,
Spodoptera litura (Fabricius), leaf beetle Pagria flavopustulata (Baly), American
serpentine leaf miner, Liriomyza trifolii (Burgess) are the pests associated with
cowpea. New pests viz., tortrycid larvae, leaf miner and girdle beetle, Oberiopsis
brevis (Gahan) were reported from cowpea under polyhouse. Sucking pests viz.,
green peach aphid, Myzus persicae (Sulzer), mealy bug, Ferrisia virgata (Cockerell),
thrips,
Astrothrips
tumiceps
(Karny),
Thrips
hawaiiensis
(Morgan),
Frankliniella schultzei (Trybom) spotted red mite, Tetranychus sp, and leaf feeders
viz., pumpkin caterpillar, Diaphania indica (Saunders), American serpentine leaf
miner, Liriomyza trifolii (Burgess) are associated with salad cucumber under
polyhouse conditions. The natural enemies observed were coccinellids, syrphids and
spiders viz., Oxyopes javanus (Thorell),
Oxyopes sunandae (Tikader) and
Argiope pulchella (Thorell) from both cowpea and salad cucumber. The data on
preliminary survey revealed that both sucking and leaf feeder pests caused significant
damage to cowpea and salad cucumber inside polyhouse.Experiments were carried out in CRD to evaluate the efficacy of new
generation insecticides viz. acetamiprid 0.10 g L -1 , imidacloprid 0.20 mL L -1 ,
thiamethoxam 0.30 g L -1 , thiacloprid 0.25 mL L -1 , dimethoate 1.50 mL L -1 against
sucking insects viz., A. craccivora, M. persicae and R. pedestris and acaricides viz.,
spiromesifen 0.80 mL L -1 , fenpyroximate 0.60 mL L -1 , dimethoate 1.50 mL L -1
against Tetranychus sp. Spinosad 0.30 mL L -1 , chlorantraniliprole 0.30 mL L -1 ,
flubendiamide 0.10 mL L -1 , indoxacarb 1.00 mL L -1 , quinalphos 3.00 mL L -1 were
tested against leaf feeders viz., L. trifolii and D. indica.
Evaluating the efficacy of new generation insecticides, thiamethoxam 0.30 g
L -1 and imidacloprid 0.20 mL L -1 were found to be effective against sucking pests
which reduced the mean population of A. craccivora to 7.33 and 12.67 aphids plant -1
respectively and M. persicae to 4.67 and 11.67 aphids plant -1 respectively after 15
days of treatment. However, thiamethoxam 0.30 g L -1 and imidacloprid 0.20 mL L -1
were found to be equally effective in managing
R. pedestris which reduced the
population to 0.20 bugs plant -1 . Spiromesifen was recorded to be the best by reducing
the population to 10.50 and 16.25 mite plant -1 in cowpea and salad cucumber
respectively. Chlorantraniliprole 0.30 mL L -1 and spinosad 0.30 mL L -1 reduced the
population of leaf miner to 0.60 and 0.40 larvae plant -1 in cowpea respectively and
0.20 and 0.60 larvae plant -1 in salad cucumber respectively and no larvae of D. indica
were recorded in chlorantraniliprole 0.30 mL L -1 and flubendiamide 0.10 mL L -1
treated salad cucumber 15 days after spraying.
The dissipation (persistence/ degradation of residues) study showed that the
promising insecticide thiamethoxam 0.30 mL L -1 persisted upto 7 and 5 days in
cowpea and salad cucumber respectively and imidacloprid 0.20 mL L -1 persisted upto
one day in both cowpea and salad cucumber and spiromesifen 0.80 mL L -1 persisted
upto 7 and 5 days in cowpea and salad cucumber respectively. Chlorantraniliprole
0.30 mL L -1 and spinosad 0.30 mL L -1 persisted upto 5 and 7 days in cowpea and 3
days each in salad cucumber respectively.From the present study it is concluded that both sucking pests and leaf feeders
are causing significant damage in cowpea and salad cucumber under polyhouse
conditions. Application of thiamethoxam 0.30 g L -1 and imidacloprid 0.20 mL L -1
effectively manage the sucking pests viz., A. craccivora, M. persicae and R. pedestris.
Spiromesifen 0.80 mL L -1 was found to be the best to manage the Tetranychus sp.
Chlorantraniliprole 0.30 mL L -1 and spinosad 0.30 mL L -1 were found to be effective
in managing leaf feeders in both cowpea and salad cucumber. A harvest interval of 5
to 7 days should be given to ensure the safety of the produce from the polyhouse to
the end users.