Document Type : Research Paper
Authors
1
Former MSc. Student Department of Plant Protection, Faculty of Agriculture, University of Mohaghegh Ardabili, Ardabil
2
Professor, Department of Plant Protection, Faculty of Agriculture, University of Mohaghegh Ardabili, Ardabil
3
Assistant Professor, Department of Plant Protection, Faculty of Agriculture, University of Mohaghegh Ardabili, Ardabil
Abstract
Beet armyworm,Spodoptera exigua (Hübner) (Lep.: Noctuidae), is a polyphagous insect pest inflicting substantial economic damage to many crops including corn, cotton, beet, tomato, celery, lettuce and alfalfa. In this study the effect of 10 commercial hybrids of corn (SC700, DC370, SC704, SC260, SC500, Keynes540, Keynes410, KSC260, KSC400 and KSC301) on the beet armyworm was investigated through a comparison of the feeding indices of the pest as on these hybrids. The experiment was conducted in a growth chamber set at 25±2 oC, 65±5 % RH and a photoperiodism of 16:8 (L:D) hours. Different larval instars of the beet armyworm (third, fourth and fifth instars) demonstrated the highest (33.40%) vs. the lowest (2.95%) values of Efficiency of Conversion of Ingested food into biomass (ECI) on hybrids SC260 and Keynes 540, respectively. The highest (60.52%) vs. the lowest (3.01%) efficiency of conversion of digested food into biomass (ECD) were obtained on hybrids SC260 and Keynes540, respectively. The highest (9.96) vs. the lowest (1.42) Consumption Indexes (CI) were observed on hybrids Keynes540, and SC260, respectively. Index of Relative Growth Rate (RGR) was the highest on hybrid SC500 (6.74) while the lowest on hybrid KSC260 (0.54). Relative Consumption Rate (RCR) of S. exigua was the highest on hybrid Keynes540 (1.06) while the lowest on KSC260 (0.17). The results finally revealed that Keynes540 was a partially resistant hybrid as compared with the other ones, tested in feeding of different larval instars of S. exigua.
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