EJPAU 2007. Chaturvedi I. ECONOMIC THRESHOLD LEVEL AND MONITORING SYSTEMS: REALITY AND PRACTICALITY IN <I>Helicoverpa armigera </I>(Lepidoptera: noctuidae)

Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.

2007
Volume 10
Issue 2

Topic:

Horticulture

ELECTRONIC
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES

Chaturvedi I. 2007. ECONOMIC THRESHOLD LEVEL AND MONITORING SYSTEMS: REALITY AND PRACTICALITY IN Helicoverpa armigera (Lepidoptera: noctuidae), EJPAU 10(2), #06.
Available Online: http://www.ejpau.media.pl/volume10/issue2/abs-06.html

ECONOMIC THRESHOLD LEVEL AND MONITORING SYSTEMS: REALITY AND PRACTICALITY IN HELICOVERPA ARMIGERA (LEPIDOPTERA: NOCTUIDAE)

Indira Chaturvedi
Department of Zoology, Post Graduate College, Bilaspur, India

ABSTRACT

Field trials and sampling of commercial crops were carried out in Chhattisgarh region of India, to assess the impact of Helicoverpa armigera Hb. on chickpea (Cicer arietinum) at several larval densities and crop stages. The seasonal damage (i.e. pods damaged during crop growth) recorded was consistently higher than damage at harvest over almost the entire cropping season. The largest relative differences between both damage inspections occurred when infesting at early crop growth stages. Population estimates from destructive sampling and a rapid plant scouting method were related to pod damage, and a nominal economic threshold of one larva per plant was derived. In commercial demonstration trials, unsprayed controls and different insecticide treatments were used to obtain a range of H. armigera infestations and crop damage where standard calendar spraying practice was compared with no spraying, calendar-based applications maintained damage below 2.8%, when crops were sprayed on the basis of IPM scouting recommendations, the highest level of damage was 2.1% despite larval populations exceeding two per plant in five crops. Another study revealed that total and marketable yield in the trap-cropped plot was higher and damaged pods lower than in the monocropped chickpea. This article describes how preliminary studies of egg and larval distributions and damage assessment trials were used to develop an initial estimate of a threshold that would maintain damage below the 5% commercially acceptable level.

Key words: Helicoverpa armigera, Cicer arietinum, Economic threshold level.

Indira Chaturvedi
Department of Zoology,
Post Graduate College, Bilaspur, India
Behind Mehta Building
Jarhabhata, Sindhi Colony,
Bilaspur-495001 (Chhattisgarh), India
email: ind_chaturvedi@yahoo.com

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.