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Life History and Population Energetics of the Dobson Fly, Corydalus Cornutus

1978; Wiley; Volume: 59; Issue: 6 Linguagem: Inglês

10.2307/1938225

1939-9170

Arthur V. Brown, Lloyd C. Fitzpatrick,

Insect Pheromone Research and Control

Rates and energies of consumption (C), egestion (F), assimilation (A), respiration (R), growth (P g ), production of exuviae (P e v ), and production of egg masses (P r ) with associated efficiencies, and effects of seasonal temperature, weight and life—history stage upon them were examined for a typical individual and cohort of Corydalus cornutus (L.) from a stream in north—central Texas. Dobson flies are univoltine with 11 larval instars. Emergence, oviposition, and hatching occurred from late May into August. The typical dobson fly hatched in mid—June, grew rapidly until November, and again in March, reaching adult size prior to pupation in early June. A0dult females fed to provide energy to yolk eggs, produce cases and for maintenance during their week of reproductive activities. Metabolic compensation enabled larval dobson flies to maintain fairly constant rates of R during winter (6.07 J g — 1 h — 1 , 5—15°C) and summer (16.15 J g — 1 h — 1 , 20—30°C); with a seasonal acclimatization threshold occurring between 15—20°C. Metabolic constancy is adaptive and probably contritubed to high ratios of P/R (1.94) and P/A (66%) for individual larvae. Rates of C, F, A, and R, but not assimilation efficiency (AE = A/C X 100), were influenced by temperature and size. The energy budget for a typical dobson fly during the 47 wk as a larva was: C = 17,435, A = 14,401, F = 3,033, P g = 8,682, P e v = 828 and R = 4,892 J. Embryos respired 0.45 J/wk, prepupae 1,494 J/wk, male pupae 2,130 J/wk, female pupae 1,900 J/wk, male adults 2,615 J/wk and female adults 3,075 J/wk. Prepupal and pupal exuviae were 602 J and 502 H respectively. The average adult female's minimal reproductive effort was 2,791 J for eggs and 774 J for egg cases, 54 and 100% of her A and P respectively, 17% of her life—history A. Annual energetics of the larval population were; C = 165,343, A = 136,574, F = 28769, P g = 54,610, P e v = 15,096, P r = 1,502—1,711 and R = 66,869 J m — 2.