Evaluation of biorational insecticides and DNA barcoding as tools to improve insect pest management in lablab bean (Lablab purpureus) in Bangladesh

Margaret R. Douglas, Jan Chang, Kohinoor Begum, Sevgan Subramanian, John F. Tooker, Syed Nurul Alam, Srinivasan Ramasamy

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Abstract

Lablab bean (Lablab purpureus) is a popular vegetable crop in Bangladesh, but farmers growing this crop experience significant losses to insect pests despite heavy reliance on conventional insecticides. We conducted field studies to improve pest management in lablab bean by testing biorational insecticides as alternatives to conventional insecticides for the control of pod borers (Maruca vitrata) and aphids (Aphis craccivora), and characterizing flower-inhabiting thrips as an emerging pest in this crop. In field experiments, spinosad was the most promising biorational we tested, suppressing pod-boring caterpillars more effectively than thiamethoxam or quinalphos. In contrast, azadirachtin (neem) did not significantly suppress any of the insect pests we measured, although target aphid populations were generally low at our research site. Using DNA barcoding at the coxI locus combined with morphological identification, we found eight thrips taxa inhabiting lablab bean flowers, dominated by Megalurothrips usitatus and M. distalis/peculiaris. A preliminary regression analysis indicated that these flower-inhabiting thrips reduced lablab bean yield. Our results suggest that spinosad may be useful within lablab bean IPM programs, and that these programs will likely need to incorporate tactics against thrips to effectively protect yield. Finally, we found that DNA barcoding was a valuable tool for pest identification in an understudied crop and region, but that to reach its full potential will require an investment in more comprehensive reference libraries.

Original languageEnglish (US)
Pages (from-to)1326-1336
Number of pages11
JournalJournal of Asia-Pacific Entomology
Volume21
Issue number4
DOIs
StatePublished - Dec 2018

Fingerprint

Lablab purpureus
insect control
DNA barcoding
Bangladesh
insecticides
Thysanoptera
spinosad
flowers
insect pests
Megalurothrips
pods
Aphidoidea
pest identification
Maruca testulalis
quinalphos
Aphis craccivora
thiamethoxam
plant pests
azadirachtin
Azadirachta indica

All Science Journal Classification (ASJC) codes

  • Insect Science

Cite this

Douglas, Margaret R. ; Chang, Jan ; Begum, Kohinoor ; Subramanian, Sevgan ; Tooker, John F. ; Alam, Syed Nurul ; Ramasamy, Srinivasan. / Evaluation of biorational insecticides and DNA barcoding as tools to improve insect pest management in lablab bean (Lablab purpureus) in Bangladesh. In: Journal of Asia-Pacific Entomology. 2018 ; Vol. 21, No. 4. pp. 1326-1336.
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Evaluation of biorational insecticides and DNA barcoding as tools to improve insect pest management in lablab bean (Lablab purpureus) in Bangladesh. / Douglas, Margaret R.; Chang, Jan; Begum, Kohinoor; Subramanian, Sevgan; Tooker, John F.; Alam, Syed Nurul; Ramasamy, Srinivasan.

In: Journal of Asia-Pacific Entomology, Vol. 21, No. 4, 12.2018, p. 1326-1336.

Research output: Contribution to journalArticle

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AU - Douglas, Margaret R.

AU - Chang, Jan

AU - Begum, Kohinoor

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AU - Ramasamy, Srinivasan

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