Introduction of Diamond back moth, Plutella xylostella , their distribution, causes by DBM on all cruciferous crops, their natural enemy complex, like parasitoids, predators in detail and also the effect of abiotic factors.
4. INTRODUCTION OF DIAMOND BACK MOTH (DBM)
• The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is one of
the most destructive cosmopolitan pests of cruciferous crops.
• It is a very destructive pest in cruciferous of Canada.
• Also in Southern Sindh (Hyderabad and Karachi region) of Pakistan.
• Moths are highly migratory and have been recorded to travel a distance of about 1500 km at
400-500 km per night (Chapman et al. 2002).
• The DBM is multivoltine with four to 20 generations per year in temperate and tropical
regions, (Harcourt 1986; Vickers et al. 2004).
• DBM was the first crop insect to be reported resistant to DDT in 1953 in Java, Indonesia, and
now in many crucifer-producing regions.
• worldwide over 135 parasitoid species have been recorded to attack various stages of DBM,
with most common ones comprising 6 spp. of egg parasitoids, 38 larval, and 13 pupal
parasitoids (Lim 1986; Talekar & Shelton 1993).
• Certain ants, flies, lacewings, hemipterans, beetles, spiders and birds also prey on its larvae
(Anonymous 1996; reddy et al. 2004).
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• Some predators such as Chrysoperla carnea Stephens (Neuroptera: Chrysopidae) were
attracted to DBM (Reddy et al. 2004).
• Some ants such as Anomma nigricans (illiger) (Hymenoptera: Formicidae) are major control
agents in Periurban areas of Benin, west Africa (goudegnon et al. 2004).
• Egg parasitoids are not always host specific and may pose a threat to non-target species in a
region. For example, Trichogramma Brassicae Bezdenko, which was inundatively released
against the European Corn Borer in Switzerland.
• Larval parasitoids have the greatest control potential and suggested that the most effective
belong to the Hymenopteran genera Microplitis (Braconidae), Cotesia (Braconidae), and
Diadegma (Ichneumonidae).
• A few pre-pupal and pupal parasitoids of the genus Diadromus (Ichneumonidae) also
contribute to DBM control (Kirk et al. 2004).
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10. Trichogramma chilonis
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• Primary eggs parasitoids of Lepidopterans.
• also in Coleoptera, Diptera, Hemiptera, Hymenoptera and
Neuroptera.
• Insert eggs singly (solitary).
• There are approximately 650 spp.
• Trichogramma wasps multiply rapidly because new adult
emerges within a week.
11. Cotesia plutellae
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• Adults are small (2-3mm), dark wasps.
• A major solitary, koinobiont, larval endoparasitoid of
DBM.
• Cotesia plutellae could parasitize larvae of all four
instars of P. xylostella, but it preferred 2nd and 3rd
instars.
12. Diadegma insulare
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• Diadegma insulare is a dominant, solitary, synovigenic,
koinobiont, larval parasitoid of Diamond back moth.
• A small Ichneumonid wasp with reddish-brown legs and
abdomen.
• It pupates inside the cocoon made by mature DBM larva
replacing the host pupal covering with its own cocoon which
may have a distinctive white band.
• D. insulare wasps are visible as dark bodies inside the
cocoon, before adult D. insulare emerges.
• She does not sting and paralyze her prey.
13. Oomyzus sokolowskii
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• It is a gregarious larval-pupal koinobiont, endoparasitoid of
the Diamond back moth.
• These parasitized all larval and pupal stages, but exhibited a
strong preference for larvae over pre-pupae or pupae.
18. ABIOTIC FACTORS
• High temperature, relative humidity and heavy rain are important factors affecting the DBM
population.
• Maximum humidity and rainfall adversely affected the population of P. xylostella, unfavorable
for the immature stages (Ahmed et al., 2010).
• Egg production and larval survival of P. xylostella are inhibited by temperature above 30°C.
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