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Molecular Entomology 2012, Vol.3, No.4, 18
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19
and overall conservation of ecosystem. Thus, before
initiating further biological control attempts in
brassica crops, it is very essential to know the
arthropod fauna in this ecosystem of the region and it
also crucial to understand various tropic levels in these
crops. Therefore, studies were carried out to know the
exact biodiversity and seasonal activities of arthropod
fauna residing into it.
2 Results
A total of 15 insect pests were observed in
brassicaceous crop ecosystems of the region. The
large white cabbage butterfly (
P. brassicae
) and
Lipaphis erysimi
was a most serious pest of vegetable
brassica (cole crops) and oilseed brassica, respectively.
Besides, diamondback moth (
Plutella xyllostella
) was
found to be major pest of late planted cole crops.
Insect pests of brassica crops, their status and seasonal
activity recorded during the study are presented in
Table 1. About 24 natural enemies and pollinators
observed in brassicaceous crops of the region (Table
2 and Figure 1). Among predators,
Coccinella
septumpunctata
complex was found to be the most
abundant predator of aphids throughout the season
followed by syrphid flies; while
Hyposoter ebeninus
and
Diaeretiella repae
were the dominant parasitoid
of
Pieris
species and aphids, respectively. In
C.
septumpunctata
complex, about three different types
of polymorphic and polychromic elytral patterns
were observed (Plate No. 1 to 3); while two chromic
pattern (orange and red) were found in case of
C.
transversalis
complex. Among non-insect predators,
four types of spider’s viz., Jumping spiders (
Marpissa
calcuttaensis
and
Phidippus
spp), Lynx Spiders
(Argiope pulchella and Oxyopes rubisternum), Wolf
spiders (
Lycosa pseudoannulata
) and Orb Spinners
(
Leuchge decorate
,
Larinia tabia
and
Cyrtophora
carrisae
) were commonly seen throughout the season.
Different species of syrphid flies, bumble bee,
carpenter bee and honey bees were observed as chief
pollinators of oilseed brassica (Table 2).
Table 1 Biodiversity and seasonal activity of insect pests in brassicaceous crops of Meghalaya, India
SN Common name
Scientific name
Crops
Season
Peak activity Status
1
Mustard aphid
Liphaphis erysimi
Oilseed brassica
Nov- May Jan-Feb
Major
pest
2
Cabbage aphid
Brevicoryne
brassicae
Oilseed and vegetable
brassica
Nov- May January
Major
pest
3
Green peach aphid
Myzus persicae
Oilseed and vegetable
brassica
Nov- May January
Major
pest
4
Cabbage butterfly
Pieris brassicae
Oilseed and vegetable
brassica
Oct- May Jan- March Major
pest
5
Cabbage leaf worm
Pieris repae
Oilseed and vegetable
brassica
Oct- Jan
November
Minor
pest
6
Diamondback moth
Plutella xylostella
Vegetable brassica
Feb- May March-April
Major
pest
7
Tobacco caterpillar
Spodoptera litura
Vegetable brassica
Feb-April
March
Major
pest
8
Cabbage semilooper
Thysanoplusia
arichalce
Vegetable brassica
Feb-April
March
Minor
pest
9
Cabbage looper
Trichoplusia ni
Vegetable brassica
Feb-April
March
Minor
pest
10
Cutworm
Agrotis ipsilon
Vegetable brassica
Oct-Jan
December
Major
pest
11
Leaf webber
Crocidolomia
binotalis
Vegetable brassica
Feb-April
March
Minor
pest
12
Green bug
Nazara viridula
Oilseed and vegetable
brassica
Feb- May March
Minor
pest
13
Flea beetle
Phylletreta
cruciferae
Oilseed and vegetable
brassica
Feb- May March
Minor
pest
14
Leaf beetle
Monolepta signata
Oilseed and vegetable
brassica
Nov- May February
Minor
pest
15
Mustard sawfly
Athalia
lugens
proxima
Oilseed brassica
Nov- Dec December
Minor
pest