title: Effects of dietary sodium on performance, flight and compensation strategies in the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae).
abstract: BACKGROUND
  Sodium is critical for many physiological functions in insects. Herbivorous insects should expend considerable energy to compensate for sodium deficiency due to low sodium concentration in most inland plants upon which they feed. However, sodium compensation behaviors such as mud-puddling have been observed in some species but not in others. We expect that there may be other sodium compensation strategies in insects. Here, we select a rarely mud-puddling insect species, the cotton boll worm, Helicoverpa armigera, and determine the effects of dietary sodium on performance and flight, and examine their means of sodium compensation.
  
  
  RESULTS
  When freshly hatched H. armigera neonates were cultured on one of three diets differing in sodium contents (diet A, B and C with a high, middle and low sodium concentrations, respectively), the larvae on diet C grew larger, had a higher mortality rate and a shorter development period than those on diet A and B. The larvae previously fed from 1st to 3rd instar on diet C consumed more subsequent diet when they were transferred to diet A or C at 4th instar, comparing to those previously fed on diet A. Moreover, any 4th-instar larvae on diet C consumed a greater amount of food than those on diet A, no matter which diet the larvae had previously ingested from 1st to 3rd instar. Moths from diet A and B flew more rapidly than those from diet C, with similar sugar and lipid utilization rates among the three test groups. When a 5th-instar cannibal from diet A, B or C and a 5th-instar victim from diet A were housed together, many more cannibals from diet C ate their victims. When a victim from diet A, B or C was provided, a cannibal from diet C was more likely to eat the victim from diet A. When newly emerged moths had been exposed to 3% sodium chloride solution for all scotophase period, the average weight increase (proxy for sodium solution intake) for moths from diet A was lower than those from diet B or C.
  
  
  CONCLUSIONS
  Sodium-deficient diet resulted in rapid growth and development of H. armigera larvae, decreased larvae survival, and reduced flight speed of H. armigera adults. To compensate for sodium deficiency, H. armigera ingested a large quantity of larval food, increased larval cannibalism incidence and harvested sodium during the adult stage.
authors.affiliation: Department of Entomology, Nanjing Agricultural University; Key Laboratory of Monitoring and Management of Plant Diseases and Pests, Ministry of Agriculture, Nanjing, 210095, China. liguoqing001234@yahoo.com.cn.
authors.forename: Kai
authors.initials: K
authors.lastname: Xiao
authors.forename: Ke
authors.initials: K
authors.lastname: Shen
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Zhong
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Li
references.citation: J Insect Physiol. 2009 Jan;55(1):78-84
references.pmid: 19028501
references.citation: Nature. 1968 Mar 9;217(5132):922-8
references.pmid: 5642846
references.citation: J Exp Biol. 1992 Nov 1;172(Pt 1):323-334
references.pmid: 9874745
references.citation: Science. 1932 Mar 25;75(1943):339-40
references.pmid: 17797677
references.citation: Biol Lett. 2006 Sep 22;2(3):321-4
references.pmid: 17148393
references.citation: J Biol Chem. 1957 May;226(1):497-509
references.pmid: 13428781
references.citation: J Insect Physiol. 2006 Mar;52(3):320-6
references.pmid: 16388821
references.citation: Oecologia. 1999 Apr;119(1):140-148
references.pmid: 28308154
references.citation: Proc Natl Acad Sci U S A. 2006 Mar 14;103(11):4152-6
references.pmid: 16537500
references.citation: Anim Behav. 2000 May;59(5):899-915
references.pmid: 10860518
references.citation: Proc Natl Acad Sci U S A. 1973 Oct;70(10):2745-8
references.pmid: 16592111
references.citation: Nutr Rev. 1976 Aug;34(8):225-35
references.pmid: 967371
references.citation: Science. 1995 Dec 15;270(5243):1816-8
references.pmid: 8525374
references.citation: Science. 1974 Jul 26;185(4148):372-4
references.pmid: 4834370
references.citation: J Insect Physiol. 2006 Jul;52(7):771-7
references.pmid: 16769081
references.citation: Zoolog Sci. 2004 Feb;21(2):181-8
references.pmid: 14993830
references.citation: Gen Comp Endocrinol. 1979 Nov;39(3):350-7
references.pmid: 499761
references.citation: J Chem Ecol. 2001 Jun;27(6):1119-31
references.pmid: 11504018
references.citation: Proc Natl Acad Sci U S A. 2008 Nov 18;105(46):17848-51
references.pmid: 19004798
references.citation: J Insect Physiol. 2008 Apr;54(4):656-62
references.pmid: 18316092