Responses of three successive generations of beet armyworm, Spodoptera exigua, fed exclusively on different levels of gossypol in cotton leaves
1State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China
2College of Plant Sciences and Technology, Huazhong Agricultural University, Wuhan 430070, China
3Chinese Research Academy of Environmental Sciences, No.8 Dayangfang Anwai, Chaoyang, Beijing 100012, PR China
Abstract
The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), is an important pest of numerous crops, and it causes economic damage in China. Use of secondary metabolic compounds in plants is an important method used to control this insect as a part of integrated pest management. In this study the growth, development, and food utilization of three successive generations of S. exigua fed on three cotton gossypol cultivars were examined. Significantly longer larval life-spans were observed in S. exigua fed on high gossypol cultivar M9101 compared with those fed on two low gossypol cultivars, ZMS13 and HZ401. The pupal weight of the first generation was significantly lower than that of the latter two generations fed on ZMS13 group. Significantly lower fecundity was observed in the second and third generations of S. exigua fed on M9101 compared with S. exigua fed on ZMS13 and HZ401. The efficiency of conversion was significantly higher in the first and third generations fed on HZ401 compared with those fed on ZMS13 and M9101. A significantly lower relative growth rate was observed in the three successive generations fed on M9101 compared with those fed on ZMS13 and HZ401. Cotton cultivars significantly affected the growth, development, and food utilization indices of S. exigua, except for frass and approximate digestibility. Development of S. exigua was significantly affected by relative consumption rate and efficiency of conversion of ingested food, but not by relative growth rate or approximate digestibility, suggesting that diet-utilization efficiency was different based on food quality and generation. Measuring the development and food utilization of S. exigua at the individual and population levels over more than one generation provided more meaningful predictions of long-term population dynamics.
Keywords: food utilization, secondary compounds
Abbreviation:AD, approximate digestibility; ECI, efficiency of conversion of ingested food (%); RCR, relative
consumption rate (mg/g/day); RGR, relative growth rate (mg/g /day)
Correspondence: a*wugang@ioz.ac.cn, bguojy@mail.caas.net.cn, cwanfangh@mail.caas.net.cn, dxiaonw@craes.org.cn, *Corresponding author
Received: 6 December 2008 | Accepted: 10 June 2009 | Published: 29 September 2010
Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.
ISSN: 1536-2442 | Volume 10, Number 165
Wu G, Guo JY, Wan FH, Xiao NW. 2010. Responses of three successive generations of beet armyworm, Spodoptera exigua, fed exclusively on different levels of gossypol in cotton leaves. Journal of Insect Science 10:165, available online: insectscience.org/10.165
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