RESPONSES OF SOMATIC TISSUES OF DEVELOPMENTAL STAGES
OF VARIEGATED GRASSHOPPER, ZONOCERUS VARIEGATUS (L.)
(ORTHOPTERA: PYRGOMORPHIDAE) TO STARVATION
K.O. ADEMOLU*1, O.A. JODA2 and A.A. OSIPITAN1
1-Department of Pure and Applied Zoology, 
Federal University of Agriculture, Abeokuta, Nigeria
2- Department of Crop Production, 
Olabisi Onabanjo University, Ago-Iwoye, Nigeria
*corresponding author: kennyademolu@yahoo.com
Abstract - Nymphs and adult stage of Zonocerus variegatus respond to environmental
stress differently. The response of somatic tissues to 96 hours starvation across the
post embryonic developmental stages of Zonocerus was investigated in this study.
The organic substances (lipids, glucose and protein) concentrations were measured
by standard methods before and after starvation exercise in the somatic tissues (femoral
muscles, fat body and haemolymph) and the difference calculated. The adult stage
experienced highest weight loss of 0.22g from the initial weight, while the 1st instar
stage had the least weight loss of 0.10g from the initial weight. Glucose was the most
depleted haemolymph metabolite (0.50-3.40mg/dl) and the 1st instar stage lost the
least amount of metabolites. In the fat body, the highest glucose concentration was
lost by the adult stage  (5.70mg/dl) while the least was loss by the 1st instar stage.
Lipids were the most depleted metabolite in the femoral muscles and the adult stage
similarly lost the highest concentration. Comparison of means showed this pattern of
metabolites loss in the three somatic tissues: glucose>lipids>protein. Despite the
highest loss in concentration of metabolites, the adult stage still fared better than
other stages of development during starvation because of higher stored reserves.
Early instar stages of Z. variegatus are thus less complicated and easier to control
than the tough adult stage. 
KEY WORDS: somatic tissues, starvation, instar, adult stage, Zonocerus variegatus,
metabolites
191
ACTA ENTOMOLOGICA SLOVENICA
LJUBLJANA, DECEMBER 2017    Vol. 25, øt. 2: 191–198
Izvleček – ODZIV TELESNIH TKIV RAZVOJNIH STOPENJ KOBILICE ZONO-
CERUS VARIEGATUS (L.) (ORTHOPTERA: PYRGOMORPHIDAE) NA
STRADANJE
Ličinke in odrasla stopnja kobilice Zonocerus variegatus se različno odzivajo na
okoljski stres. V tej raziskavi smo preučevali odziv telesnih tkiv postembrionalnih
razvojnih stopenj kobilic na 96 ur stradanja. Koncentracije organskih snovi (lipidov,
glukoze in proteinov) smo merili s standardnimi metodami pred in po stradanju v
telesnih tkivih (stegenskih mišicah, maščobnem telesu in hemolimfi) in izračunali ra-
zliko. Odrasla stopnja je doživela največjo izgubo teže, 0,22g, od začetne teže, prva
stopnja ličinke pa z 0,10g najmanjšo izgubo teže od začetne. Glukoza je bila najbolj
izčrpan hemolimfni metabolit (0,50 – 3,40 mg/dl) in ličinka prve stopnje je izgubila
najmanj metabolitov. V maščobnem telesu se je koncentracija glukoze najbolj zman-
jšala pri odrasli stopnji (5,70 mg/dl), najmanj pa pri ličinki prve stopnje. Lipidi so
bili najbolj izčrpan metabolit v stegenskih mišicah in odrasla stopnja je podobno
izgubila največ koncentracije. Skupna primerjava izgube metabolitov v treh telesnih
tkivih je pokazala vzorec:  glukoza>lipidi>proteini. Kljub največji izgubi koncentracije
metabolitov je odrasla stopnja bolje kot druge razvojne stopnje preživela stradanje
zaradi več shranjenih zalog. Zgodnje razvojne stopnje Z. variegatus zato nadziramo
lažje in z manj zapleti kot zdržljivo odraslo stopnjo.
KLJUČNE BESEDE: telesna tkiva, stradanje, razvojne stopnje, odrasla stopnja, Zonocerus
variegatus, metaboliti
Introduction
In Nigeria, Zonocerus variegatus occurs in cultivated land with the nymphs and
adult stage sharing same habitat which extends from rainforest zone  to Guinea Sa-
vannah in the north (Youdeowei, 1974). The life cycle consists of six nymphal stages
and adult stage, which is the reproductive stage. Ademolu et al (2013) reported that
all nymphal stages together lasted for 111.1 days while female and male adults lived
for 127.9 and 101.2 days respectively. Hence, the total life cycle of Z. variegatus was
between 210.8 and 237.5 days (Ademolu et al., 2013).
Though living in the same habitat, the various developmental stages behave dif-
ferently: 1st -3rd instars are gregarious in nature and prefer exclusively Chromolaena
odorata while later instars and adult stage feed predominantly on Manihot esculenta
and live dispersed (Toye, 1982). Similarly, an initial rise in the concentrations of
tissue metabolites was observed during the 1st -5th nymphal stage of Z. variegatus
which dropped at the 6th instar and rose again at the adult stage (Ademolu et al.,
2007).
Muse (2003) observed that starvation had significant influence on the longevity
of the adult stage.  Likewise, Idowu and Idowu (2001) reported that starvation reduced
the volume of the repellent gland obtained from Z. variegatus. In Locusta migratoria,
lipid reserves were mobilized from the fat body during starvation, resulting in increase
in total haemolymph lipids and decrease in the fat body lipids (Jutsum et al., 1975).
Acta entomologica slovenica, 25 (2), 2017
192
Similarly, in L. migratoria and fruit beetles (Paechnoda sinuata) glycogen stores are
metabolized during the initial stage of starvation and later switch to lipid and protein
metabolism happens when carbohydrates are exhausted (Hill and Goldswothy, 1970;
Auerswald and Gade,2000).
Starvation process reduced the colony forming unit (cfu)  in the midgut, as well as
the concentration of organic and inorganic substances in the haemolymph, fat body
and femoral muscles of adult Zonocerus (Ademolu et al.,2011). Since the physiology
of each stage of development differs, will their tissues respond differently to starvation
exercise? This study attempts to examine the response of each developmental stage
of Z. variegatus to the process of starvation.
Materials and methods
Insect samples
Newly hatched 1st instar nymphs of Z.variegatus were collected from a known
oviposition site on the campus of Federal University of Agriculture, Abeokuta (FU-
NAAB), Nigeria. Being gregarious in behavior at this stage, hundreds were collected
with the aid of sweep net and were transferred into wire cages (30x30x45 cm). On ar-
rival at the insectary of Pure and Applied Zoology, FUNAAB, the insects were sepa-
rated into seven cages each containing 60 individual insects and allowed to molt into
its different developmental stages. The 2nd instar to the 6th instar stage individuals
were maintained on leaves of M. esculenta (cassava) before molting into the next
stage of development.
Each developmental stage was starved for 96 hours (4 days) at 2nd day after emer-
gence following methods adopted by Ademolu et al (2011).
Data Collection 
(a) Body weight
The body weight of the insects was taken both before and after the four days star-
vation experiment using sensitive digitalized weighing balance (Mettler Toledo, AE,
240).
(b) Tissue collection and preparation
Three somatic tissues (haemolymph, fat body and femoral muscles) were harvested
from Z. variegatus before and after the 96 hours starvation period.
Haemolymph was collected following methods described by Ademolu et al (2011).
A micro needle was inserted into the mid ventral axis of the thorax and the haemolymph
coming out was collected into a calibrated syringe. The sample was centrifuged and
the supernatant was kept in refrigerator for further analysis. 
The peripheral fat body was carefully picked and 0.5g of it was homogenized in
5mls of distilled water and the homogenate was used for analysis.
Following the opening of the hind femora, the femoral muscles were removed by
forceps into the petri dishes, dried to constant weight at 50oC in an oven at 12 hours
K. O. Ademolu, O. A. Joda, A. A. Osipitan: Responses of somatic tissues of developmental stages of variegated grasshopper,
193
and from it, 0.5g was macerated in 0.05M KCl. The homogenate was centrifuged and
supernatant obtained was kept in refrigerator until further usage.
(c) Analysis of samples
The protein, glucose and lipids of the samples were determined following the
methods of Henry et al (1997), Baunmniger (1974) and Grant et al (1997) respec-
tively.
Statistical analysis 
All analyses were carried out in triplicates and the data were subjected to analysis
of variance. Separation of significant means was done by Duncan Multiple Range
Test.
Results
The influence of starvation on the body weight of developmental stages of Z. var-
iegatus is shown in Table 1.  The body weight of all developmental stages was sig-
nificantly (p<0.05) affected by starvation. The weight loss was progressively increasing
as the insect passed through the developmental stages with the adult stage having the
highest weight loss.
Table 2 shows the influence of starvation on the haemolymph metabolites of de-
velopmental stages of Z. variegatus. There was a significant difference in the amount
of glucose loss due to starvation by the different stages of development with the adult
stage recording the highest glucose loss. Although no significant difference was
recorded in the amount of protein and lipids loss to starvation by the developmental
stages, adult stage had the highest numerical loss.
Acta entomologica slovenica, 25 (2), 2017
194
Stages of
development 1
st Instar 2nd Instar 3rd Instar 4th Instar 5th Instar 6th Instar Adult
Average initial
weight 0.10
c 0.12c 0.14c 0.18c 0.30b 0.50b 0.97a
Average final
weight 0.09
c 0.11c 0.12c 0.16c 0.25bc 0.45b 0.75a
Average weight
loss 0.01
c 0.01c 0.02c 0.02c 0.05b 0.05b 0.22a
Table 1: Effects of 96 hours starvation on the body weight (g) of developmental
stages of Zonocerus variegatus (L).
Mean values in the same row having the same superscript are not significantly
different (p>0.05).
The loss of metabolites in the fat body of developmental stages of Z.variegatus
after 96 hours starvation is shown in Table 3. There was progressive increase in the
amount of metabolites loss as the insect passed through 1st instar stage to the adult
stage (except lipids). The results also show that more of glucose and lipids were lost
to starvation than protein.
The loss of femoral muscle metabolites due to 96 hours starvation of developmental
stages of Z.variegatus revealed differences in the amount of metabolites lost by each
stage of development (Table 4). The adult stage recorded the highest glucose and
lipids loss while the earlier instars had lowest loss. 
K. O. Ademolu, O. A. Joda, A. A. Osipitan: Responses of somatic tissues of developmental stages of variegated grasshopper,
195
Table 2: Haemolymph metabolites loss during 96 hours starvation of develop-
mental stages of Zonocerus variegatus (mg/dl).
Developmental Stages Glucose Protein Lipids 
1st Instar 1.1b 0.3 1.2
2nd Instar 1.7b 0.2 1.4
3rd Instar 1.8b 0.4 1.3
4th instar 1.2b 0.4 1.1
5th Instar 3.4a 0.3 1.5
6th Instar 0.5c 0.4 0.7
Adult 3.2a 0.6 1.9
Mean values in the same column having the same superscript are not significantly
different (p>0.05).
Table 3: Fat body metabolites loss during 96 hours starvation of developmental
stages of Zonocerus variegatus (mg/dl).
Developmental Stages Glucose Protein Lipids 
1st Instar 0.9c 0.5b 1.5b
2nd Instar 1.5c 0.4b 2.3b
3rd Instar 1.0c 0.8b 2.5b
4th instar 3.2b 2.7ab 2.1b
5th Instar 3.5b 2.1ab 8.1a
6th Instar 0.2c 2.0ab 1.7b
Adult 5.7a 3.3a 2.1b
Mean values in the same column having the same superscript are not significantly
different (p>0.05).
Discussion
The body weight loss of Z. variegatus due to 96 hours starvation increased gradually
from 1st instar to the adult stage. This reflects trend of energy depletion, that is,
energy depletion was more in the later instars than the early instars. The food reserves
as a result of food consumption by insects increased with nymphal growth owing to
increased food requirement for growth and metabolic function, thus during starvation
stress, such reserves are lost or depleted in high quantity (Omkar and Jones, 2003).
Also, the active nature (dispersal) of the later instars and adult stage deplete their re-
sources more compared to the early instars that are gregarious in habit and therefore
conserve or less exhaust their resources (Toye,1982). Furthermore, the difference in
the way the nymphal stages and adult responded to food deprivation might be related
to their water balance, because adults are more susceptible to water loss than the
nymphs.
Somatic tissues of Z. variegatus lost significant quantity of their metabolites con-
centration due to starvation. Similar observation was made by Perez-Mendoza et al.
(1999) where starvation reduced the lipids content and body weight of Lesser grain
borer, Rhyzopertha dominica. Similarly, Auerswald and Gade, (2000) reported that
in P. sinuata, carbohydrates were first metabolized during the initial stage of starvation,
then shift to lipids and proteins happened when carbohydrates were exhausted. How-
ever, the fact that protein component of these tissues was also depleted possibly sug-
gests that lipids and glucose metabolism were not sufficient to meet the requirement
of the insect, resulting in the net reduction of protein concentration.
Comparison of means revealed that less of protein and more of glucose and lipids
were lost by the somatic tissues due to starvation. This is not unexpected as carbohy-
drates and lipids are the predominant metabolites utilized during initial stage of star-
vation (Hill and Goldworthy, 1970; Hainsworth, 1981). In an experiment using Oxya
Acta entomologica slovenica, 25 (2), 2017
196
Table 4: Femoral muscles metabolites loss during 96 hours starvation of develop-
mental stages of Zonocerus variegatus (mg/dl)
Developmental Stages Glucose Protein Lipids 
1st Instar 0.8 0.1 1.5c
2nd Instar 0.6 0.5 1.1c
3rd Instar 0.7 0.5 2.3c
4th instar 2.3 1.5 1.7c
5th Instar 0.9 2.2 1.5c
6th Instar 2.7 1.8 5.0c
Adult 3.0 2.1 7.5a
Mean values in the same column having the same superscript are not significantly
different (p>0.05).
japonica (Acrididae: Orthoptera), a significant decrease in the total haemolymph
lipids and carbohydrates was observed when deprived of food for 96 hours (Lim and
Lee, 1981). During starvation trials in two Drosophila species, rates of lipid and
protein metabolism were similar, but carbohydrate metabolism was several fold higher
(Marron et al., 2003).
The fat body of Z. variegatus experienced higher metabolites loss due to starvation
than other two somatic tissues examined. This might likely be due to the higher
amount of metabolites present there and thus expectedly higher loss to starvation.
Ademolu et al (2007) observed that fat body stores more protein and lipids than the
haemolymph and femoral muscles during postembryonic development of Z. variegatus.
Similarly, the fat body was reported to have stored more glycogen, fat, protein and
other substances brought into it by the haemolymph (Hannerland and Shirk, 1995).
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