Assessment of Proximate and Mineral Status of Rhinoceros Beetle Larva, Oryctes rhinoceros Linnaeus (1758) (Coleoptera: Scarabaeidae) from Itokin, Lagos State, Nigeria
Larvae of Rhinoceros beetle (Oryctes rhinoceros) Linnaeus, 1758 (Coleoptera; Scarabaeidae) is well relished as snacks or main meal in Southwest Nigeria but little is known about its proximate and nutritional composition. The beetle larvae were therefore collected from Itokin, Lagos State, Nigeria and analysed using standard procedure of the Association of Analytical Chemists. The proximate analysis revealed that the sampled beetle larvae contain 16.97+0.04% moisture, 12.92+0.02% ash, 1.16+0.06% crude fibre, 48+0.05% crude protein, 20.35+0.08% carbohydrate and 0.06+0.61% fat. The ash content is a pointer that the insect has high mineral content hence the mineral element analysis was carried out using the Atomic Absorption Spectrophotometer (AAS). Following acid digestion the larva sample was analyzed for Calcium (Ca), Sodium (Na), Iron (Fe) and potassium (K), respectively. The results showed that the O. rhinoceros sample analysed contain 0.03+0.004 (mg/100 g) Ca, 0. 0.17+0.03 (mg/100 g) K, 21.82+0.60 (mg/100 g) Na, 4.10+0.07 (mg/100 g) Fe. The values were within the recommended daily allowance for these minerals. These results indicate that the beetle larva has huge potential as a base for new food/feed products of extensive nutritive value.
to cite this article:
R.A. Olowu, B.A. Moronkola, O.O. Tovide, A.A. Denloye, K.N. Awokoya, C.E. Sunday and O.O. Olujimi, 2012. Assessment of Proximate and Mineral Status of Rhinoceros Beetle Larva, Oryctes rhinoceros Linnaeus (1758) (Coleoptera: Scarabaeidae) from Itokin, Lagos State, Nigeria. Research Journal of Environmental Sciences, 6: 118-124.
Received: February 03, 2012;
Accepted: March 21, 2012;
Published: June 26, 2012
The Rhinoceros beetle Oryctes rhinoceros Linnaeus, 1758 (Coleoptera:
Scarabaeidae), so called as a result is a pest of coconut in most part of the
world, particularly in Southern Asia but in Africa, especially in Nigeria, it
lives in and feeds mostly on oil and Raphia palms (Ayejuyo
et al., 2001; Okaraonye and Ikewuchi, 2009).
Old stems of coconut, Raphia and oil palms, also serve as breeding sites
for the beetle (Ayejuyo et al., 2001; Okaraonye
and Ikewuchi, 2009). Except for damage to coconut palms, the larvae are
harmless (Thomas et al., 2005; Voet
et al., 2006; Kurian et al., 1983).
Their larval stage is long (about two years). Eggs are laid and larvae develop
in decaying logs or stumps, piles of decomposing vegetation or sawdust, or other
organic matter (Ekpo and Onigbinde, 2005; Bedford,
1980). The eggs are deposited into the soil by the female during the warmer
seasons (Nishida and Evenhuis, 2000). After a month the
egg hatches and it enters the larval stage. The larval stage can last several
years depending on the species. Other species of Rhinoceros Beetles have three
instars, which mean they molt three times (Voet et al.,
2006). The larva stays underground for six months to one year. While they
are there they grow and molt twice before entering the pupa stage. Human entomophagy
in Africa has been documented earlier (Ayejuyo et al.,
2001). In Lagos State, they are found in places like, Itoikin along Ikorodu-Ijebu-ode
expressway, Epe, Owode-Ajegunle and also in Ikorodu and Badagry. Previously,
Rhinoceros beetle larvae were fried and eaten as a bush delicacy but now they
are made available in commercial quantity in local markets where people in urban
areas can purchase them. These larvae popularly consumed in the south western
region of Nigeria among the Yoruba tribes and are usually called Ipe while in
Ijaws tribes it is known as osori and also called tam in Ogoniland. The popular
name for this pest in the Ibo land which is the Southern part of Nigeria is
Utukuru (Ekpo and Onigbinde, 2005; Okaraonye
and Ikewuchi, 2009). It is either consumed raw, boiled, smoked or fried.
It may be eaten as part of a meal or as a complete meal (Ayejuyo
et al., 2001). The consumption of this species is also well prominent
in Edo and Delta state. Meanwhile, global environmental health concerns calls
for research to determine the level of pollutant in these animals as well as
other consumables food since human depend mostly on their protein (Nwude
et al., 2011).
The objective of this study was to investigate the nutritional composition of the larva, with a view to revealing its potential for use as food supplement and formulation of new food/feed products.
MATERIALS AND METHODS
Sample description: The samples of Oryctes rhinoceros larva were
collected from Itokin, a town in the South Western axis of Nigeria, which is
on the boundaries of Lagos and Ogun States, about 20 km from Ijebu-Ode in Ogun
State and also about 15 km to Ikorodu in Lagos State, it lies on latitude 60°N
and longitude 30°E and has an elevation of 141 ft. Lagos. Five samples were
collected over a period of five weeks. The samples were collected and kept in
well ventilated plastic containers and were conveyed to the laboratory, where
they were utilized within 24 h. The samples were dried except the ones for moisture
content and were crushed using pestle and mortar previously washed with acid.
The homogenized samples were later dried for 3 h in the oven at 105°C. Proximate
analysis of the samples was carried out in triplicates, according to standard
methods (AOAC, 1999) in order to determine the moisture,
crude protein, ash, crude fat and total carbohydrate.
The concentration of the Calcium, Iron, Potassium and Sodium element in each
sample was determined by a BUK scientific, VGP 210 model flame atomic absorption
spectrophotometer after acid digestion as described by AOAC (AOAC,
1999). The sample was incinerated to a white ash at 550°C in a muffle
furnace for (2 h) cooled and the ashes were later transferred into a 100 mL
beaker. About 50 mL of concentrated trioxonitrate (v) acid (HNO3)
was added to the sample ash in the beaker. The beaker was covered with a water
glass and allowed to digest for 2 h to prevent foaming then cooled (Pearson,
1976). About 10 mL of hydrochloric acid was added to the sample ash and
boiled for 4 h on a hot plate at 80°C. The samples were refluxed with 40
mL of distilled water and filtered using Whatman no 4 filter paper and a glass
funnel. The sample filtrate was brought up to 100 mL with distilled water in
a 100 mL volumetric flask.
RESULTS AND DISCUSSION
The proximate composition of the O. rhinoceros larva by percentage is shown in Table 1. From the proximate composition of the larva analysed, crude protein has the highest percentage (Fig. 1) followed by the carbohydrate, then the moisture while fat content was the least. The low value obtained for the moisture content revealed a short shelf life for the larva and the statistical investigation showed that there exist no significant different between the level of the minerals analyzed in the larva. A strong correlation was observed between the mineral elements investigated in the analyzed samples as shown in Table 3.
The crude protein content observed here for Oryctes rhinoceros larva
is higher than those reported for cow milk, egg, termite, Rhynchophorus phoenicis
and beef but lower than those of caterpillar and locust (Shils
and Young, 1988; Ekpo and Onigbinde, 2005). The
high percentage of protein as show in Fig. 1a is an indication
that the rhinoceros beetle larva is very rich in protein and can supplement
the daily need of the body, being 23-56 g day-1 (Aremu
et al., 2007; Chaney, 2006a, b).
The high level of crude protein in the larva is relevant in the food value available
for enzyme formation, antibodies and possibly some hormones (Singh,
2004; Ige et al., 1984). Ash has been reported
to be a measure of the mineral content in a sample (Alinnor
and Akalezi, 2010). The ash content is also relatively high, when compared
with reported values for meats, meat products, poultry and egg (Scott,
1980). It contained a moderate quantity of crude fibres which is lower than
what was reported by Ogungbenle et al. (2009)
for flour. Crude fibre has been reported to enhance nutritional performance
as well as act as catalyst in digestion and absorption in the intestines (Ogungbenle
et al., 2009). Insects are known to be rich sources of various macro
and trace elements. These elements are probably accumulated for future use in
adult exoskeletal and connective tissue formation.
|| Proximate composition of Oryctes rhinoceros larva
||Graphical representation of (a) proximate and (b) mineral
composition of Oryctes rhinoceros larva, Moi: Moisture content, CF:
Crude fat, CP: Crude protein, CFi: Crude fibres and TC: Total carbohydrates
|| Mineral profile of Oryctes rhinoceros larva
|| Correlations of variation between the mineral element in
the Oryctes rhinoceros larva sample
Ash content of 12.92% was obtained which is a measure of the mineral elements
present in samples acting as a pointer that the larva should contain more mineral
elements (Alinnor and Akalezi, 2010; Scott,
1980). The obtained moisture content is higher than that reported for caterpillar
but lower than those for termite, cow milk, egg and Rhynchophorus phoenicis
(Chaney, 2006b). This high moisture content is an
indication that O. rhinoceros has a short shelf life. Moisture
content of food is usually used as a measure of the stability and susceptibility
to microbial contamination as well as an index to water activity of the food
(Ayo et al., 2010). Therefore, dehydration would
generally improve the shelf life/preservation of the larva and, in addition
increase the relative concentrations of the other food components (Singh,
2004). The carbohydrate content is moderately high but higher than those
reported for Rhynchophorus phoenicis, caterpillar, termite, cow milk
and egg. However, fibre and fat content obtained were found to be lower than
that reported for some insects such as termites (Ekpo and
The sample of the Oryctes rhinoceros were analysed for some mineral
element utilizing atomic emission spectroscopy and a higher value of 21.82 mg
g-1 was recorded for sodium as shown in Fig. 1b
and Table 2 compared to other mineral elements present in
the sample. The order of concentration values of this mineral element is Na>Fe>Ca>K.
All these minerals are essential minerals required by the body for its proper
functioning. The value obtained for sodium fall within the required daily allowance
for food. However, sodium exhibit various function that are essential to body
immune system sodium is an element that is vital to human life when in combination
with potassium and chlorine and form a very important part of blood plasma.
Sodium also allows our bodies to maintain the right blood chemistry and the
correct amount of water in our blood and as well allow our muscles to contract
normally. In the absence of sodium, our cells could not get the nutrients they
need to survive. Sodium aid proper digestion of food consumed into he body system.
Normal functioning of our nervous system also depends on this important element.
The loss of sodium via sweat can result in dehydration, weakness and mental
confusion. Many athletes drink sports drinks that contain a lot of sodium, like
Gatorade, to prevent this from happening (NRC, 1989).
Other mineral element such as Fe, Ca and K also exhibit various functions in
the body system (Nelson, 1987).
The average value obtained for iron in the analysed sample is 4.10 mg g-1
which is higher than earlier report by Ayejuyo et al.
(2001) but is within the recommended daily allowance hence can argument
the daily requirement for iron. Iron exhibit many functions in the body and
is used by the body to make tendons and ligaments. It is also important for
maintaining a healthy immune system and aid digestion of certain things in the
food that we consume. Iron obtained from our diet is an essential part of haemoglobin
enabling the transport of oxygen thereby enabling efficient functioning of blood
in our body system. When there is iron deficiency it results in tiredness, decreased
alertness and attention span as well as prevents the muscles from functioning
properly. If the lack of iron in the bodies is severe, "iron deficiency anaemia"
may result, which essentially means that the blood will carry insufficient oxygen
to the body. Iron deficiency anaemia is probably the most common nutritional
disease in the world, affecting at least five hundred million people (NRC,
It can be said that the rhinoceros beetle is rich in minerals especially in
sodium and can supplement the body needs of sodium and that of Iron. It is rich
in Iron which is a component of haemoglobin, myoglobin, cytochrome, non-heme
proteins, myeloperoxidase (Chaney, 2006b) etc. The iron
content of the larva can supplement the daily requirements for iron and manganese,
respectively. The low level of calcium and potassium obtained in this work however
indicates that it will be insufficient for growing children, older women and
individuals prone to osteoporosis. Calcium is one of the most abundant elements
in our bodies and accounts for 2 to 3 pounds of our total body weight. It is
very important in building and maintaining strong bones and teeth as well as
for many other things. It helps control things like muscle growth and the electrical
impulses in your brain and is also necessary in maintaining proper blood pressure
and is responsible for clotting of blood. Calcium also enables other molecules
to digest food and make energy for the body as a result increase in calcium
intake in our diet is believed to lower high blood pressure and prevent heart
disease and also used in treatment of arthritis (NRC, 1989).
Furthermore, the average concentration of potassium in the analysed sample
was found to be 0.18 mg g-1 which is lower than earlier report (Ayejuyo
et al., 2001). Potassium is an extremely important element in the
human body and as been reported as an important mineral that help in maintaining
electrolyte balance in human (Appiah et al., 2011).
Our bodies are made up of millions of tiny cells, such as brain cells, skin
cells, liver cells etc. These cells make up the different organs in our bodies,
such as the brain, skin, or liver. Potassium is very essential to cells and
without it, we could not survive. Cells are the small building blocks of the
human body. Cells have many ways by which they can control what (and how much)
enters and leaves. When a nerve cell does this, it actually pumps out chemicals,
which give the message to the next nerve cell and eventually to the brain. Potassium
helps control the release of those chemicals and without potassium, the nerve
cell couldnt send those messages to your brain. But it is not just nerve
cells that depend on potassium but most, if not all, of our cells depend on
it. It is also important to know that in the plant kingdom, potassium is one
of the 3 main elements that make plant life possible. The obtained value is
lower than the acceptable range recommended by WHO for food products which revealed
that Oryctes rhinoceros will be insufficient for growing older women,
children as well as person prone to osteoporosis and colon cancer (Nelson,
Conversely, statistical analysis (Table 3) using Pearson correlation coefficient analysis at 95% level of confidence showed a strong correlation between Ca and Fe, Na and Fe in the Oryctes rhinoceros larva sampled with r value of 0.769 and 0.851, respectively. This shows that there is a common source of these mineral elements in the studied O. rhinoceros larva.
It can be concluded from the result that the larva could form a base for new food/feed products of considerable nutritive value, especially in view of its high protein content hence the consumption of O. rhinoceros as food should be encouraged as a supplement for protein.
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