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OPUSCULA ZOOLOGICA 
INSTITUTI ZOOSYSTEMATICI UNIVERSITATIS BUDAPESTINENSIS 
TOM. I. 1 1956 . FASC. 1-4. 


Investigations concerning. the energy turn-over of the 
Hyphantria cunea Drury caterpillars 


By 
G. GERE 
“(Zoosystematical Institute of the University of Budapest) 


The primary consumers, i.e. organisms feeding on living vege- 
table material are of great importance in productive biology. As a . 
result of their metabolism, the. radiating. energy fixed by the plants 
becomes accessible to the other members of the animal communi- 


. ties. The whole complicated system of the other organism of. accu- 
` mulative type (consumer) in the animal communities is established 


by their activity, They play a decisive role in directing the energy 


and material supplies of the animal communities to different levels. 


Neverthless our konwledge is very insufficient as to the details of 
their functioning. 
These considerations led me to examine the energy turn-over 


of a caterpillar feeding on green leaves. I have chosen for the in- 


vestigation Hyphantria cunea DRURY, recently carried from Ame- 
rica into Europe, for this species.can be easily reared, and besides, 
I have already made some researches concerning its all over meta- 


 bolism (1.3,). 


I used caterpillars of second generation, reared in the labora- 
tory with open windows and fed the animals on leaves of Acer 
Negundo L. At the times of molting and when they have reached 
their maximum weight, a sufficient number of them were picked out, 
so were also a number of pupaé less than 24 hours of age, Their 
excrement was gathered and separated for each larval instar, The 
energy content of these and that of the leaves was measured by 
burning of 0,27 to 0,94 g abs.dry material in a bombcalorimeter, 
The energy content measured in this way and expressed in cal. 
units, are represented in table 1. The data are the mean values of ' 


2 to 4 measurements. l 
i 


energy con - 

tent (abs, 

dry material 
cal/g 


age 
(by 
moltings ) 


maxima 


Table 1. 


It leaps to one’s eye that in the first six larval instars the spe- 
cilic energy content of the excrement is only, with 3,5 to 8,1 % less, 
while the specific energy content of the caterpillar is with 19 toh 
25 % more than that of the food, The situation changes in the se-h 
venth larval instar. The energy content of the excrement decreasesy 
(89,7 % of the food) while the energy content of the caterpillars, 
considerably increases; finally a pupa with 1 g abs.dry weight aty 
the pupation has an energy content surpassing by 51 % that of the 
food of equal weight. 


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: 

Interpreting these data, we can say, that - though the organism 
of the caterpillar is composed, of course, of materials richer in energy 
‘then the leaves wich it feeds on - nevertheless the energy content 
of ihe excrement is considerably high, too. In other words: these 
‘animals can utilize the energy content of the food but in a relatively 
smali degree; a great part of it gets into the excrement, i.e, to the 
excremental level. The energy store of the excrement of the cater- 
pillars is only slightly lower then that of the green leaves, This fact 
directs our attention to the great importance of the course the excre- 
ment is going to take. By the same reason we emphasize the very 
‘important role played by the organism of coprophagous-recurerative 
itype. 


A caterpillar consumes, before reaching 
its maximal weight, 376,2 mg. of food 
(abs.dry material), of which 


is gets into the |is consumed for 
accumulated | excrement maintenance of 
the organism 
10,8 x 


Hp ee | 

46,1 mg | 2805 mg | 40,6 
E A Star ee with the food 
before reaching its maximal weight, 
1647,5 cal of energy, of which 


is gets into the EES 
ae ae ae irradiates 
| 709% | 12,5 % 
aa 2.7 is 1168,2 cal. 206,7 cal. 
Table 2. 


The changes, mentioned above, taking place in the last one of 
larval instars, can be explained by the fact that in this phase 
animal ~ in order to secure the processes of the metamorphosis - 
res materials of high energic content, principally fats (2.). This 
cess is undoubtedly connected with the simultaneous decrease 
the energy content of the excrement. 


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Calculations concerning the quantitative relations of the energy 
turn-over of the caterpillars can be made by comparing the data 
given in table 1 with the data of the all over metabolism of the 
animals. 

The data given in the heading 1 of table 2 show the approxi- 
mate percentage distribution of the dry material of the nutriment 
(accumulated, excreted and oxidated materials). In collecting these 
data, I relied up on my previous investigations (1.3.). By means 
of these data, the all- over metabolism of caterpillars of identical 
ontogenesis can be quantitatively calculated. (See table 2, heading 
2.) So the outlines of the quantitative relations of the energy turn- 
over of these animals can be determinated. (See table 2, headings 
3 and 4.) Details of calculation are omitted. It must be emphasized 
that the caterpillars utilize the food in a considerably varying measure 
during their ontogenesis. This fact was taken into consideration in 
the calculations, 

The data of table 2 show that an average caterpillar receives. 
with the food more than 1500 cal energy before reaching its maxi- - 
mum weight. 16,6 % of this energy is accumulated, 70,9 % gets into 
the excrement, and 12,5 %-is radiated out of the system, during 
the processes maintaining the life-functions. All these data de- 
monstrate the importance of the excremental phase. 

The energy-contents were determined in the Institute of Phy- 
_ sical Chemistry of the Technical University, Budapest. f 

: 4 
LITERATURE d 

1. BALOGH,J. & GERE,G.: Uber die Emahrungsbiologie undi 
Luftstickstoffbindumg der Hyphantria-Raupen. Acta Biol.Hung.4.1953. 
p.431-452. - 2. GERE,G.: Untersuchung und produktionbiologische 
Bewertung der chemischen und gewichtsmässigen Veränderungen § 
der Hyphantria cunea Drury während ihrer Umwandlung. Zool. Ib, 
(Physiologie ). (In the press.) - 3. GERE,G.: A Hyphantria cunea, 
Drury hernyók tápan yagfogyasztásának mennyisége a testnagyságuk- 
hoz viszonyitva. Ann, Inst. Prot. Plant. Budapest, (In the press.) - 
4. ROEDER, K.D.: Insect Physiology. New York - London. 1953., 
pp. 1100. - 5, RUBNER,M,: Emährung. In: BOHMER, A, JUCKENACK,A, 
& TILLMANS,J.: Handbuch der Lebensmittel chemie, Berlin. 1933, 

p. 1145-1248 


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