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The importance of weaver ant (Oecophylla smaragdina Fabricius) harvest to a local community in Northeastern Thailand

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Ants of the species Oecophylla smaragdina are a valued resource in some Southeast Asian countries since they are edible. In Thailand they are an expensive delicacy collected in high numbers from natural habitats. In this study we interviewed 25 ant collectors in Nakhon Ratchasima Province to elucidate the extent of ant collection and its socioeconomic impact. On average more than 3 persons per village collected the ants, each collecting on average 219 (± 107.5) kg of ants per year. This yield led to a daily income of 411 THB (12.1 US$) per working day during the 4-5 month ant harvesting season, corresponding to approximately 1.5 - 2.6 times the minimum wage (162 THB day-1) in the province. On average, the yearly income from ants constituted 30 % of the total household income among the ant collectors and additionally supplied their families with an animal food source. The major issues considered problematic by ant collectors were the increasing number of people collecting ants and high travel distances to ant sites. Increased harvesting pressure may put the natural ant populations at risk. We discuss ant farming as a potential solution to these problems.
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The importance of weaver ant (Oecophylla smaragdina Fabricius)
harvest to a local community in Northeastern Thailand
WISSANURAK SRIBANDIT1, DECHA WIWATWITAYA1, SANTI SUKSARD2 & JOACHIM
OFFENBERG3*
1 Department of Forest Biology, Kasetsart University, Bangkok 10900, Thailand
2 Department of Forest Management, Kasetsart University, Bangkok 10900, Thailand
3 Department of Biological Sciences, University of Aarhus, DK-8000 Aarhus C, Denmark
* Corresponding author’s email: offenberg@biology.au.dk
Abstract. Ants of the species Oecophylla smaragdina are a valued resource in some
Southeast Asian countries since they are edible. In Thailand they are an expensive
delicacy collected in high numbers from natural habitats. In this study we interviewed
25 ant collectors in Nakhon Ratchasima Province to elucidate the extent of ant collection
and its socioeconomic impact. On average more than 3 persons per village collected
the ants, each collecting on average 219 (± 107.5) kg of ants per year. This yield led to
a daily income of 411 THB (12.1 US$) per working day during the 4-5 month ant
harvesting season, corresponding to approximately 1.5 - 2.6 times the minimum wage
(162 THB day-1) in the province. On average, the yearly income from ants constituted
30 % of the total household income among the ant collectors and additionally supplied
their families with an animal food source. The major issues considered problematic by
ant collectors were the increasing number of people collecting ants and high travel
distances to ant sites. Increased harvesting pressure may put the natural ant
populations at risk. We discuss ant farming as a potential solution to these problems.
Keywords: insects as food, ethnoentomology, entomophagy, Nakhon Ratchasima,
ant farming, socioeconomy
ASIAN MYRMECOLOGY Volume 2, 129 - 138, 2008
ISSN 1985-1944 © W. SRIBANDIT, D. WIWATWITAYA, S. SUKSARD & J. OFFENBERG
INTRODUCTION
The weaver ants belonging to the genus
Oecophylla consist of two extant species – O.
smaragdina which is distributed throughout tropi-
cal Asia, Australasia and some Pacific islands and
O. longinoda distributed throughout tropical Af-
rica (Lokkers 1986). The species share similar bio-
logical and ecological characteristics. They are
both polydomous canopy ants that build leaf nests
on their host trees. Nests are constructed by draw-
ing together leaves and fixing them with silk pro-
duced from their larvae (Cole & Jones 1948;
Offenberg et al. 2006). The nests are easily visible
and scattered throughout the canopy territory of
the ants which can cover up to 1500 m2 for a single
large colony (Hölldobler 1983). The ants use a wide
range of host trees and prefer sunny habitats.
Therefore they are usually abundant in disturbed
habitats with trees or bushes. Weaver ants are
aggressive and will prey on most arthropods en-
tering their territory and additionally scavenge on
a wide range of organisms including vertebrates
(Dejean 1991; Wojtusiak et al. 1995). Due to their
predatory habit Oecophylla ants are recognised
as biological control agents in tropical tree crops
as they are able to protect a variety of crops against
many different insect pests (Van Mele 2008; Way
& Khoo 1992). In this way they are utilised indi-
rectly as an alternative to chemical insecticides. It
is less well known that the ants can be utilised
directly also, as a commercial product. There exist
at least three different markets for the use of these
ants in Southeast Asia: (i) in Chinese and Indian
traditional medicines (Chen & Alue 1994; Oudhia
2002), (ii) as a valued feed for song birds in Indo-
130 Thai weaver ant harvest
nesia (Césard 2004), and (iii) as a prized human
delicacy in Thailand and other Asian countries
(Bristowe 1932). In Chhattisgarh, India, traditional
healers believe that regular intake of O.
smaragdina will prevent rheumatism – a view shar-
ed by practitioners of traditional Chinese medi-
cine (Chen & Alue 1994; Oudhia 2002). The Indian
healers also prepare oils in which they dip col-
lected ants. After 40 days oils are used externally
to cure rheumatism, gout, ringworm or other skin
diseases, or else as an aphrodisiac (Oudhia 2002).
In Java there is great enthusiasm for keeping cap-
tive songbirds. According to bird lovers the lar-
vae and pupae of O. smaragdina provide essen-
tial protein and vitamins to their birds and so will
improve the bird’s performance. For use as a bird
food they are willing to pay up to US$1.4 per kg of
ant brood. Lower-quality ant brood is used to feed
chickens where it is believed to accelerate feather
growth and flesh production (Césard 2004). The
tradition of including Oecophylla ants in food and/
or traditional medicine has been reported from
various cultures in Thailand, India, Myanmar,
Borneo, Philippines, Papua New Guinea, Australia
and Congo (De Foliart 2008 and references
therein). Especially in Thailand O. smaragdina is
considered a delicacy and has been eaten by hu-
mans for centuries. Imagos as well as brood are
used in a variety of Thai dishes and are easily
obtained on many local markets throughout the
country during the ant harvest season. Larvae and
pupae are preferred over imagos and the queen
caste preferred over the worker castes and males.
The season in which O. smaragdina produce new
queens therefore defines the ant harvest season.
The ants are used as ingredients in soups, salads
and fried dishes and sometimes eaten raw together
with spices as a snack. The tradition of eating ants
is most prominent among the Isaan people of
Northeast Thailand and the people in Northern
Thailand but has spread to other parts of the coun-
try with the migration of people from these cul-
tures. A growing interest in the eating of ants has
led to higher demand throughout Thailand with
increasing prices as a result. Thus, the collection
of ants is becoming more profitable and the har-
vest pressure on local O. smaragdina populations
may increase accordingly, potentially leading to
an unsustainable overexploitation of these ants in
natural habitats.
The purpose of the present paper is to assess
the socio-economic significance of ant harvesting
and thereby evaluate the potential future pressure
on this resource. We seek to identify factors that
limit the trade, and conduct a preliminary
assessment of the need for alternatives to the
harvest of naturally occurring populations in order
to prevent future over-harvesting of ants. In this
context we discuss the development of ant farming
as a way to prevent the unsustainable utilisation
of ants as a food resource. Thailand is one of the
countries where the utilisation of ants as a natural
food resource is most prominent and organised,
with the harvest of O. smaragdina in Northeastern
Thailand particularly developed. The harvest of
this ant in a province in Northeastern Thailand
was therefore selected for the study.
METHODOLOGY
In 2005 a survey was conducted to document and
elucidate the extent of O. smaragdina harvesting
in Northeastern Thailand and its contribution to
local livelihoods. Seven villages located in two
districts (Wang Nam Khiow and Pak Tong Chai),
around Kasetsart University´s Forestry Student
Training Station in Nakhon Ratchasima Province,
were chosen at random. In the year 2000 Nakhon
Ratchasima Province had a population of 2,565,685
people with a median age of 29 years and a sex
ratio of 97 (males per hundred females). Sixty-six
percent of the population worked within the
agricultural sector and 31 % of the population was
self-employed, 33 % was employees and 36 % were
unpaid family workers (UNESCAP 2000). The two
districts covered an area of 2,504 km2 with a total
of 296 villages and a population of 156,576 people,
of whom 64 % were between 15 and 59 years old
(UNESCAP 2000). While population data for the
individual study villages was unavailable, average
village size was therefore 534 persons (ignoring
the fraction of the population living in cities). The
national forest area in the vicinity of the villages
was mainly composed of dry deciduous
dipterocarp forest, which is characterised by a
limited soil layer on a rocky surface. The result is a
landscape with low tree density, an open canopy
and sparse and dry undergrowth affected by
regular fires. Due to the open canopy and limited
tree height it is easy to detect and harvest O.
131
W. Sribandit, D. Wiwatwitaya, S.Suksard & J. Offenberg
smaragdina nests in this habitat. In the seven
villages all people collecting O. smaragdina were
interviewed using structured questionnaires. The
questions were centred on methods used to collect
ants, yields, location of activities (spatially and
temporally), challenges associated with the
profession and the economy associated with ant
harvesting. The questionnaire survey was
conducted by Wissanurak Sribandit between 1
March and 30 April 2006 and all questions referred
to ant harvesting activities carried out by ant
collectors during 2004 and 2005.
Secondly, more than ten ant harvesters were
observed in the field in April 2006, February 2007
and April 2007 in order to describe the methods
used to harvest the ants. Variation measures (±)
given in the results refer to standard deviation.
The currency exchange rate used between THB
and US$ was 1:0.02936.
RESULTS
In the seven villages a total of 25 people between
41 and 62 years were harvesting ants (mean = 3.57
± 4.12 persons village-1). Given an estimated 349 in
each village within the age group 15 to 59 years
(an overestimate as some of these worked in cities),
at least 1 % of the working population was
harvesting ants. Four collectors were men, 21 were
women and the average size of their households
was 4.6 (±1.89) persons. All 25 persons were
interviewed for the study. Ants were harvested
mainly in national forests, where 76 % of the
harvesters collected ants, and secondly in villages
and farm areas, where 40 % collected ants. Only 8
% harvested ants in plantation areas (percentages
exceed 100 since some people harvest in more than
one type of habitat). Assuming the seven villages’
ant ‘catchment area’ was an equal share of the two
districts, the 25 collectors used an area of
approximately 59 km2.
Ant harvesting techniques
All collectors used the same method to harvest
ants: ants were harvested from the early morning
when the ants were least active and until midday.
A long (6-10 m) bamboo stick with a net mounted
close to the pointed tip was used to pierce the
Oecophylla leaf nests. When the bamboo stick
was shaken, imago worker ants (hereafter called
workers), imago virgin queens (hereafter called
virgin queens) and brood dropped into the net
(Figs. 1-3). From the net the ants were poured into
a bucket with water enabling the collectors to
separate the different ant castes and developmental
stages. Workers were separated from virgin queens
and imagos were separated from the brood which
comprised both larvae and pupae (Figs. 4-5). After
separation the ants were either kept in a refrigerator
or stored in water at ambient temperature. In this
way it was claimed that ant brood could stay fresh
for up to 12 days. As a protection against ant bites,
collectors used rubber boots powdered with fine
starch powder. The combination of rubber and fine
powder prevented the ants from crossing the
boots. The same powder was also used on hands
and on the bamboo stick to impede ant attacks.
The ant harvest started in January when 16 % of
the collectors were active, peaked in February-
April when 80-92 % were active, and ceased in
May during which only 8 % were collecting ants.
Outside this season none of the collectors
harvested ants.
Harvest yields
When collectors were asked to estimate their daily
yields they reported that the harvest per working
day averaged 2.88 (± 1.78) kg brood, 1.58 (± 1.45)
kg virgin queens and 0.08 (± 0.39) kg workers (only
one person reported harvesting workers, at 2.0 kg
workers day-1), resulting in a daily total of 4.54 (±
2.24) kg ants collector-1. When asked to estimate
their harvest yields by month and summing these
numbers, it emerged that brood yield peaked in
February-March whereas virgin-queen yield
peaked in April (Fig. 6). In total the collectors
harvested an estimated 5486 kg ants year-1; thus
each person collected on average 219.4 (± 107.5)
kg ants year-1 (or season-1). Each collected ants
on an average of 48 days ((5486 kg / 4.54 kg/day)
/ 25 ant collectors)) during the season. Assuming
254 working days in a year the average time spent
by collectors on ant collection thus equalled 19 %
of the working year. However, the collectors did
not spend the whole day but on average only 4.48
(± 1.73) hours working-day-1 on the collection of
132 Thai weaver ant harvest
Fig. 1. A Thai ant collector harvesting an Oecophylla
nest on a mango tree. Fig. 2. Harvesting net filled with freshly collected ants.
Fig. 3. An ant collector separating workers from brood
by dusting the ants with starch powder on a tray. Worker
ants seem to be repelled by the powder, and try to flee
without the brood.
Fig. 4. Ant collectors processing the harvest: separating
workers from virgin queens and imagos from brood
(larvae and pupae).
Fig. 5. The final fresh product of queen larvae and
pupae ready for the market.
133
W. Sribandit, D. Wiwatwitaya, S.Suksard & J. Offenberg
ants (ignoring the time spent selling the ants in
the market, which was not recorded in this study)
resulting in 10-11 % of the working year.
Trading and selling prices
Nine collectors sold all their harvest at markets,
four used the entire harvest for the family, one
sold all in the village and one sold all to middlemen.
The remaining ten collectors sold their harvest to
more than one purchaser. On average ant collectors
estimated that 50.6 (± 18.2) % (219 kg year-1 x 0.506
= 111 kg year-1) of the harvest was sold at town
markets, 22.4 (± 41.1) % (= 49 kg year-1) was eaten
by the family, 13.2 (± 33.4) % (= 29 kg year-1) was
sold in the village, 10.2 (± 39.0) % (= 22 kg year-1)
was sold to middlemen and 3.6 (± 0.0) % (= 8 kg
year-1) was sold to restaurants. The market price
of brood and virgin queens ranged from 100-200
THB (US$2.94-5.87) kg-1 with higher minimum
prices at both ends of the season; in January and
May minimum prices were between 120 and 180
THB (US$3.52-5.28) kg-1 depending on the year.
The interview data lack information on the price of
workers, but we observed workers being sold for
50 THB (US$1.47) kg-1 at the market in Pak Tong
Chai. In general the highest prices were obtained
at the town markets (~200 THB) whereas
middlemen, restaurants and people from the
villages paid less. In one case a collector obtained
Costs and income
Among the ant collectors the lowest reported total
cost associated with ant harvesting was 30 THB
(US$0.88) working-day-1 whereas the highest was
550 THB (US$16.15) working-day-1, with time (52
%, calculated based on the minimum daily wage
and the fraction of the day spent collecting) and
travel costs (47 %) making up 99 % of the total and
equipment making up only 1 % (Table 1). Travel
costs to ant sites were more costly (29 %) than
travel to markets (18 %); collectors travelled
between 0.1 and 80 km to ant sites with an average
of 16.5 (± 21.69) km working-day-1. Among the ant
collectors the total gross yearly income of the
household ranged between a minimum of 18,000
THB (US$528) and a maximum of 115,000 THB
(US$3376) (mean = 67,154 ± 27,652 THB, = US$1971
± 812), whereas the yearly gross income from ant
harvesting ranged from 4,000 (US$117.4) to 50,000
THB (US$1468) (mean = 19,884 ± 13,317 THB, =
US$584 ± 391) (Table 2). For individual collectors
the yearly income from ant harvesting thus
constituted between 10 % and 69 % of the total
yearly income with a mean of 30 % (Table 2). Based
on the yearly income and average number of
working days the daily gross and net incomes from
Fig. 6. The weight of harvested ants by month. The figure shows the sum of the monthly estimates given by all
the 25 ant collectors, averaged from 2004 and 2005.
180 THB kg-1 when selling to a middleman and 200
THB when selling at the market.
134 Thai weaver ant harvest
On average more than three people per village (at
least 1% of the working population) collected ants,
each collecting almost 220 kg of ant brood during
the 4-5-month ant harvesting season. The ant-
DISCUSSION
Economic importance
Constraints
Eighty-four percent of the collectors reported
finding it increasingly difficult to harvest ants
compared to earlier years. Among these 76 %
considered an increasing number of ant collectors
problematic, whereas 24 % found increasing travel
distance a problem and 8 % had problems with
obtaining permits. On the other hand, all collectors
found it easy to sell their harvest. Forty-eight
percent of the interviewed collectors were
interested in establishing commercial ant farms to
make collection easier and more profitable (52 %
showed no interest) but only 12 % had ideas about
how to develop ant farming.
Costs in THB Mean SD
Equipment 1.93 1.77
Travel to ant sites 51 63.84
Travel to markets 31.72 16.56
Time cost
1
90.72 44.57
Total 175.37
1Time costs were based on the minimum salary for Nakhon
Ratchasima province which was 162 THB day-1(8h).
Table 1. The costs (in Thai Baht, THB) associated
with ant harvesting. Costs are calculated per working
day.
SD = standard deviation.
the ant harvest equalled 411 THB (US$12.07) and
236 THB (US$6.93) working-day-1, respectively. In
Nakhon Ratchasima Province the legal minimum
wage (and the wage often paid to manual workers)
equals 162 THB (US$4.76) day-1 (8 hr). Thus the
net income from ant harvests was approximately
1.5 times the minimum wage for the province, or
2.6 times if it is considered that only 4.48 hours
working day-1 were spent on ant collection.
harvesting income constituted on average 30 %
(Table 2) of the collectors’ yearly household
income, yet collecting ants took up only between
10 and 19 % of a working year; thus the earnings
from the ant harvest exceeded those of other
activities for an average collector. Daily net income
from ant harvesting was 1.5-2.6 times higher than
the minimum daily salary for the area. If these
figures are typical for villages of the province, wild
Oecophylla collection is currently worth some 21
million THB (US$620,000) per year in Nakhon
Ratchasima. Furthermore, not only collectors were
supported by the ant trade. Despite the high price
of ant brood (200 THB kg-1 at markets compared
with chicken, pork and beef with price ranges of
60-70, 90-100 and 100-120 THB kg-1, respectively)
ants were easy to sell and trading via middlemen
and restaurants generated incomes to these other
links in the trading network. Additionally, the
harvest constituted a substantial part of the family
food intake with an average consumption of 49 kg
of ants per season in each collector family. We
therefore conclude that the harvest of Oecophylla
ants in the Nakhon Ratchasima area supports a
substantial part of the local community, yielding
above-average cash income and important
nutrients. The importance of the ant trade to local
labour is further pronounced by the timing of the
season which is at the end of the dry season when
the need for farming labour is minimal and thus
alternative incomes are low.
Sustainability
The 25 collectors harvested more than 5 tonnes of
ants per season from a roughly-estimated
catchment area of 59 km2; this translates to 93 kg
km-2 season-1. Harvesters reported they had no
impression of a decline in the number of ant
colonies in the area. This observation suggests
that the harvest at present is sustainable. One
reason is the Thai preference for the large virgin
queen ants. They only harvest during the queen
production season and only collect from the largest
nest where the queen brood is located. Smaller
nests, where the founding queen and worker brood
is located (Peng et al. 1998), are not harvested
from the colonies. The worker ant population is
therefore only marginally reduced and the
founding queen rarely damaged. Thus, the
135
W. Sribandit, D. Wiwatwitaya, S.Suksard & J. Offenberg
Table 2. The estimated total yearly household incomes and incomes from the ant harvest for individual ant
collectors, in Thai Baht (THB). Empty entries show collectors that were unable to estimate their yearly income
from ant harvest. F = female, M = male.
colony survival are maintained. In contrast, the
newly produced queens (and males) are not
essential to colony survival since they eventually
leave the colony for mating and establishment of
new colonies; the newly mated queens can be
collected individually or in small clusters in the
vegetation during the mating season. This is also
supported by our observations (Offenberg &
Wiwatwitaya, unpublished data) that the harvest
of ants in an experimental mango plantation in the
same area did not affect worker ant densities
negatively; all harvested colonies were still present
after one year and worker ant densities were
actually higher in harvested compared to un-
harvested colonies.
On the other hand, the number of ant
collectors was increasing. Inexperienced
newcomers may, in order to increase yield, adopt
harvesting techniques (for example harvesting
small nests) that do not consider sustainability.
We do not have information on how long ant
collection has been practised in the area, but it is
believed to be for many generations, and certain
traditional practices have been beneficial to
sustainability. For example the normal size of the
holes in the collecting net enables the majority of
workers and worker brood to escape. However,
some collectors used densely woven material with
the result that all the contents of the nests would
be collected. Also, new ant collectors may be
unaware of the ant’s biology. They could harvest
more than one ant territory at a time with the result
that workers from different colonies become mixed
and start fighting inside ant territories. This may
again reduce worker densities and leave the
colonies with weakened defences, as well as
Ant collector Gender Total income (THB) Income from ant harvest (THB) Ant income / total income
1 F 18,000 - -
2 F 24,500 5,000 0.20
3 F 25,000 4,000 0.16
4 F 38,500 4,900 0.13
5 M 40,200 5,500 0.14
6 F 46,100 - -
7 F 52,000 5,100 0.10
8 F 71,000 12,000 0.17
9 F 75,500 13,500 0.18
10 M 67,000 16,500 0.25
11 F 75,000 12,500 0.17
12 F 79,000 13,500 0.17
13 F 80,000 - -
14 F 69,000 15,500 0.22
15 F 55,000 30,500 0.55
16 F 60,000 31,500 0.53
17 F 45,050 31,000 0.69
18 F 50,000 - -
19 F 85,000 32,500 0.38
20 F 115,000 30,300 0.26
21 M 95,000 32,000 0.34
22 M 105,000 50,000 0.48
23 F 98,000 - -
24 F 110,000 - -
25 F 100,000 32,000 0.32
N251919
Average 67,154 19,884 0.30
SD 27,652 13,317 0.17
136 Thai weaver ant harvest
Ant farming
Ant farming may become a possible solution, to
both future over-harvesting of natural populations
and increasing costs associated with travelling to
ant sites. By limited intervention it is possible to
establish or increase ant yield in nearby crop and
non-crop trees. If trees are not sprayed with
insecticides Oecophylla colonies may establish
naturally (they occur on most mango and pomelo
trees in the vicinity) or, alternatively, they may be
artificially introduced (Peng et al. 2004).
Subsequent separation of neighbouring colonies
to prevent fighting (Peng et al. 1999) and the
provision of food and water may then increase the
yield of harvestable queen brood and generate a
profit (Offenberg & Wiwatwitaya unpublished
data). Even in fruit plantations ant farming may be
profitable since Oecophylla spp. can protect a
variety of crop trees against pest insects (Way &
Khoo 1992; Van Mele 2008 [but see Tsuji et al.
2004] and because the harvest does not markedly
reduce the densities of worker ants (the caste that
patrol the trees for pests). It follows that biocontrol
by O. smaragdina may be retained under ant
harvesting regimes. The establishment of ant
farming may reduce costs not only by creating
high-density ant sites closer to villages but also
by making the harvest of ants less time-consuming,
since cultured trees are usually smaller and thus
more easily accessible than trees in natural forests,
Parallels between Thai and Indonesian Oeco-
phylla harvesting
To our knowledge only one other study has
described traditional Oecophylla harvesting in
detail (Césard 2004). As outlined in the introduction
Césard (2004) describes the harvest of Oecophylla
brood in Indonesia where ants are used as bird
food. According to Césard (2004) the Indonesian
harvesting technique was almost identical to the
Thai technique using long bamboo poles with a
net to harvest the ant nests. In Indonesia, though,
collectors reported that the high-quality brood
(worker brood) could only be stored for
approximately two days whereas the Thais claimed
to be able to store brood for up to 12 days. This
difference may arise because the Thais refer to the
storing of virgin-queen brood whereas Indonesian
collectors refer to the storage of worker brood.
Actually, the Indonesians mention that larger
larvae can be stored for longer. In both countries
the production of sexual brood seems to take place
during the dry season, but Indonesian collectors
regard the wet season with worker brood as the
high-quality season whereas the Thais in this
study only harvest ants during the dry season,
when virgin queens are produced. Daily yields from
the dry season are similar between the countries
with an average of 2-5 kg per person per day in
Indonesia in comparison to the 4.5 kg reported
from the present study. In the wet season when
the ant larvae are smaller the daily Indonesian
average was 1.5 kg. A striking difference between
the two markets was in the market price of ant
brood. The consumer price was similar in the two
countries, at approximately US$5 kg-1 (if the THB-
US$ conversion rate is corrected to the 2004 rate =
0.025). However, Indonesian collectors obtained
only US$1.2-1.4 kg-1 when they sold their harvest
to middlemen. In contrast Thai collectors only used
middlemen for a minor part (14 %) of the harvest
introducing hostile non nest-mate workers in
proximity to the founding queens and thereby
putting them at risk. A high economic incentive to
harvest ants as documented in this study will
probably result in a steadily increase of ant
collectors and increasing competition. Thus, higher
harvest pressures and temptations to adopt
unsustainable harvesting methods may result. It
is therefore likely that the natural ant population
may be put at risk in the future as it has been seen
in Java where Oecophylla ants have become
scarce in some areas due to high harvest pressures
(Césard 2004; Suputa, Faculty of Agriculture,
Universitas Gadjah Mada, Indonesia, personal
communication December 2005). The increasing
numbers of ant collectors, long travel distances
and associated costs have made accessibility to
ant sites an important economic parameter.
where the majority of the harvest (76 %) is collected
at present. The active farming of ants may thus
reduce the pressure on natural populations. This
view is supported by the 48 % of collectors who
showed interest in ant farming. Development of
ant farming thus offers an option to maintain
economic and ecological sustainability in ant
harvesting.
137
W. Sribandit, D. Wiwatwitaya, S.Suksard & J. Offenberg
and the price difference between middlemen and
local markets was small (11 % difference in one
case). The high price difference in Indonesia is
probably based on the long distance between ant
sites and consumer markets which are mainly
situated in larger cities. Therefore middlemen with
high transportation costs are needed in the
Indonesian trade chain. Both Indonesian and Thai
collectors could easily sell all their harvest quickly
indicating high demand in both countries.
Consumers in Indonesia were reported to have to
wait for their produce to arrive. Due to high demand
Indonesian collectors also reported increasing
competition for the resource and newcomers to
the profession as well as old collectors often
disregarded the former harvesting techniques
developed to ensure sustainability. For example,
harvesting rotation intervals were being violated
with the result that Oecophylla was becoming
scarce in several exploited areas on Java.
Implication for biocontrol
Often the biting of Oecophylla ants is a major
complaint envisaged by plantation managers when
advised to use the ants for biological control and
this may hinder implementation of this
environment-friendly technology (Van Mele 2008).
It is worth noting that the Thai ant collectors
described in this study have been able to develop
techniques to avoid unacceptable levels of ant
bites, even though they are disturbing the ant
nests which are the most fiercely protected part of
the ant territory. The ant collection methods
developed by the Thais may be utilised to avoid
ant bites among plantation workers in Oecophylla-
protected crops and facilitate the implementation
of Oecophylla biocontrol (Van Mele, Cuc, Seguni,
Camara & Offenberg, unpublished data).
Future directions
In conclusion, the harvest of Oecophylla ants in
Northeast Thailand is substantial and not only for
local subsistence but an effective way of earning
cash. There is an economically-driven, increasing
interest in harvesting ants and thus increasing
pressure on natural ant populations. Ant farming
may be a solution to retain sustainability and at
the same time enhance profitability. Further studies
are needed to develop ant farming and test the
profitability of different management practises.
They include identifying the ants’ food
requirements (carbohydrates vs. protein) and the
food conversion efficiencies of different kinds of
food, locating easily-accessible, cheap and
sustainable protein sources, and investigating
impacts on existing biotic communities, including
populations of other economically beneficial
invertebrates. Also, studies examining the effect
of ant harvest pressures on local ant populations
are needed to verify the sustainability of the
present activities.
ACKNOWLEDGEMENTS
Danish International Development Assistance
(DANIDA) supported this research, project no:
104.DAN.8-744.
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ASIAN MYRMECOLOGY
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... Ants that are potentially threatened include Liometopum spp. of which the brood ('escamoles') is collected in Mexico (Ramos-Elorduy 2006); the leaf-cutter ants Atta spp. and Acromyrmex spp. of which the winged females ('hormigas culonas') are consumed throughout Central and South America (Choo 2008 ); and the weaver ant Oecophylla smaragdina of which both brood and adult ants of all castes are used as human food and animal feed (Césard 2004, Hanboonsong et al. 2013, Sribandit et al. 2008). ...
... Van Mele (2008) suggests that because of this nuisance little research has been done in using weaver ants in agroforestry practices. Weaver ants are one of the most popular edible insects in Thailand and the Lao PDR (Sribandit et al. 2008, Yhoung-Aree and Viwatpanich 2005). Sribandit et al. (2008 show the importance of the O. smaragdina trade to local livelihoods. ...
... ssiveness of the ants is however a nuisance to humans (Van Mele et al. 2009). Van Mele (2008) suggests that because of this nuisance little research has been done in using weaver ants in agroforestry practices. Weaver ants are one of the most popular edible insects in Thailand and the Lao PDR (Sribandit et al. 2008, Yhoung-Aree and Viwatpanich 2005). Sribandit et al. (2008 show the importance of the O. smaragdina trade to local livelihoods. They estimate an average ant harvest of 219 (± 107.5) kg per year per ant collecting household. This yield constitutes an average of 30% of the yearly household income among the ant collectors. The use of weaver ants as human food concerns predominantly the queen brood ...
... A second way to utilize weaver ants is to use them as food as described by Sribandit et al (2008). This tradition has been practiced in Southeast Asia for centuries and is especially well developed in Thailand where weaver ant harvest in a single province has been estimated to amount to 105 ton ant larvae year -1 worth US$ 620,000. ...
... Further the ants have a protein content of 48.5% (dry weight) which is similar to e.g. chicken eggs and they are a priced delicacy approximately twice as expensive as common protein food such as chicken and beef (Sribandit et al 2008). Ant larvae are even exported to Asian stores in Japan and Europe. ...
Conference Paper
Canopy dwelling weaver ants (Oecophylla spp.) are used to control a variety of pests in a number of tropical tree crops. What is less familiar is the existence of commercial markets where these ants and their brood are sold for (i) human consumption, (ii) pet food or (iii) traditional medicine. In Thailand, for example, weaver ant brood is harvested in vast amounts as a delicacy and sold for twice the price of beef. As these markets provide a basis for commercial ant farming, the possibility of using plantations patrolled by weaver ants as catchment areas for ant harvest, was examined. Depending on management, 32-115 kg ant brood (mainly new queens) was harvested per ha per year without detrimental effect on colony survival and worker ant densities. This suggest that ant biocontrol and ant harvest can be sustainably integrated in plantations and double benefits derived. As ant production is fuelled by pest insects, problematic pests are converted into food and additional earnings. To assess the profitability of providing additional food for the ants, O. smaragdina food conversion efficiency (ECI) was estimated in the laboratory. This estimate suggests the feeding of weaver ants in ant farms to be profitable. Based on these measures the rate of return from ant feeding was calculated, leading to the conclusion that the feeding of weaver ants in ant farms is profitable.
... We found that the main reasons behind the wide acceptance of these two insects, apart from their taste and flavour, were that they were locally abundant throughout the year (ants) and that they could be gathered in large amounts during their swarming periods (termites). Ants and termites have actually been known for a long time to be popular food insects not just in Arunachal Pradesh, but in many parts of the world (e.g., Bergier, 1941; Bodenheimer, 1951; Malaisse and Parent, 1997; Paoletti et al., 2003; Malaisse, 2005; Sribandit et al., 2008). In India their consumption has been reported apart from Arunachal Pradesh and other regions of North-East-India, also from some rural areas of Tamil Nadu, Karnataka, Kerala, Orissa, Jharkhand and Chhattisgarh in India (Rajan, 1987; Veeresh, 1999; Oudhia, 2002; Wilsanand, 2005; Srivastava et al., 2009; Yesodharan et al., 2011 ). ...
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The nutritional potential of Oecophylla smaragdina and Odontotermes sp., two common species of insects used as food by tribal people of Arunachal Pradesh and elsewhere in India was assessed. O. smaragdina and Odontotermes sp. contained 55.28 and 33.67% protein, 14.99 and 50.93% fat, 19.84 and 6.30% fibre, 2.59 and 3.01% ash and 7.30 and 6.09% carbohydrates, respectively. The protein of both species involved 18 amino acids, including all of the essential ones with the exception of methionine, which satisfies the recommended level (score > 100). In O. smaragdina, the MUFA fraction (51.55%) dominated the lipids and was followed by SFA (40.26%) and PUFA (8.19%). In Odontotermes sp. SFAs (52.89%) were dominant, followed by MUFAs (44.52%) and PUFAs (2.59%). In both species iron, zinc and copper were the most abundant minerals and calcium, magnesium, sodium and potassium were present in substantial amounts. Respective values for anti-nutrients like phytic acid and tannin (mg/100 g) were 171.0 and 496.67 for O. smaragdina and 141.23 and 615.0 for Odontotermes sp., values much lower than corresponding ones from some common foods of plant origin. The two insects, once under controlled cultivation, could be a good choice as a replacement for some vertebrate animal food products.
... As Sporleder and Rapp (1998) reported, the population of P. wayi sinks to zero after a long and stable occupation of palm trees by O. longinoda. In addition to biocontrol, Oecophylla is used as a valuable source of food for humans (Sribandit et al. 2008), contributing directly to food security (Offenberg and Wiwatwitaya 2010) and also serve as a feed for song birds in Indonesia (Césard 2004 ). Populations of weaver ants in crop fields are, however, not stable, as they can commonly drop to very low levels in the field, resulting in inadequate crop protection. ...
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Weaver ants, Oecophylla spp, are effective predators that control a wide range of insect pests in multiplecrops when maintained at high population. Supplementary feeding, particularly during reduced food availability is one of the management practices that maintain and boost weaver ants’ populations. Experiments were conducted between September and October 2013, January and February, 2014 to determine the type of food preferred by weaver ants, O. longinoda. Twenty colonies of O. longinoda were providedwith four types of food to determine their feeding preferences. These include anchovy, chicken intestine, fish intestines and earthworms. We examined food preferred by ants based on weight of the food removed and activity of the ants on foods. Furthermore, we examined foraging behavior of ant workers on anchovy food (fresh-ground and dry-ground) in nine O. longinoda colonies. Thereafter, small and large particles of dried-ground anchovy were tested. The results showed that O. longinoda preferred anchovy to other foods provided. However, the results of Analytical Hierarchy Process showed that earthworm and fish intestine were the most accessible food types by farmers, as determined by availability, affordability and applicability. We observed more ants on fresh-ground as opposed to dry anchovy; similarly, large particles were more easily removed than was the case with small particles. Thus, during reduced food availability, farmers in the study area should use earthworms and fish intestines feeds to supplement O. longinoda colonies. Fresh moist anchovy or dry anchovy of large particle sizes can be used where available.
... African weaver ants (Oecophylla longinoda) are found in sub-Saharan Africa, while Asian weaver ants (Oecophylla smaragdina) are found in Australasia. A number of studies have been made on weaver ants from the time they were first described [1][2][3][4][5][6]with a focus on eusociality [2][3][4][5][6], interactions with plants [7, 8], and on their use as biological pest control agents [9][10][11][12][13]. Even though the Asian weaver ant, Oecophylla smaragdina, is widely distributed across the Indian subcontinent and south-east Asia extending up to Australia, very little research has been done on them, especially in India. ...
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Asian weaver ants (Oecophylla smaragdina) are arboreal ants that are known to form mutualistic complexes with their host trees. They are eusocial ants that build elaborate nests in the canopy in tropical areas. A colony comprises of multiple nests, usually on multiple trees, and the boundaries of the colony may be difficult to identify. However, they provide the ideal model for studying group living in invertebrates since there are a definite number of nests for a given substrate, the tree. Here, we briefly examine the structure of the nests and the processes involved in the construction and maintenance of these nests. We have described the spatial arrangement of weaver ant nests on trees in two distinct tropical clusters, a few hundred kilometres apart in India. Measurements were made for 13 trees with a total of 71 nests in the two field sites. We have considered a host of biotic and abiotic factors that may be crucial in determining the location of the nesting site by Asian weaver ants. Our results indicate that tree characteristics and architecture followed by leaf features help determine nest location in Asian weaver ants. While environmental factors may not be as influential to nest arrangement, they seem to be important determinants of nest structure. The parameters that may be considered in establishing the nests could be crucial in picking the evolutionary drivers for colonial living in social organisms.
... Recently, new populations are increasingly thrust into subsistence use of wild resources due to environmental and political upheaval (Pierce and Emery 2005). According to the USAID, international water and weather-related disasters doubledSribandit et al. (2008)in the 1990s resulting in exploding populations of refugees seeking water, food, and shelter. As natural disasters, drought, famine, and conflict escalate, dependence on wild plant and animal resources and the traditional knowledge of how to identify and use them becomes one of the few means of survival for millions of displaced persons worldwide (Pierce and Emery 2005). ...
Chapter
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Globally, 1.5 billion people use or trade non-timber forest products (NTFPs) with the majority of NTFP use and trade occurring at local and regional scales, generally invisible to researchers and policy makers. NTFPs cannot be measured by monetary estimations alone, as they have significant subsistence and sociocultural importance and are commonly one part of multifaceted, adaptive livelihood strategies. In spite of low-cost substitutes, both rural and urban people continue to use select forest resources for medicine, crafts, rituals, and food. And as drought, disease, famine, and conflict escalate globally, growing numbers of displaced and marginalized people depend upon forest resources for survival. In general, forests managed for timber and NTFPs retain more biodiversity and resilience than forest plantations or forests managed for industrial timber. Forests that harbor NTFPs also protect ecosystem services such as hydrological functions and soil retention and act as a buffer against climate variability. Land use change through logging, fire, and agribusiness is contributing to the degradation of forests, resulting in declining access to NTFPs for local communities. Land stewards can mitigate detrimental impacts to NTFPs by employing multiple-use management practices that emphasize ecosystem services and community needs in addition to traditional forestry outputs (timber and non-timber). For multiple-use forestry to be applied broadly, forest policies need to be cross-sectoral and scale sensitive to lessen regulatory obstacles for small holders and for common pool/property systems. In addition, forestry training needs to include a stronger social focus and improved understanding of the ecology, use, and societal and ecosystem service values of NTFPs.
Book
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Anthropo-entomophagy is not a novel phenomenon, it has been in practice from very early stages of evoluation of human beings. Additionally, the large phylogenetic distance between insects and other mammals, including humans ensures that the risks of transmission of diseases from insects to humans is very low. In the present study, a survey was undertaken to enumerate the entomophagy practiced by the indigenous communities of Mayurbhanj district & Bonai Forest Division, Sundargarh district in Odisha. The study examines in deapth the indigenous knowledge of the local people especially tribes on entomophagy, which has been used to sustain or improve their livelihoods, and so serves as a secondary source of income. The book looks into the uses and benefits of most common weaver ants (Oecophylla smaragdina) among the ethnic tribes of Santal, Munda, Bhuian, Oraon/ Oram, Kisan and Ho in Mayurbhanj district & Bonai Forest Division of Odisha. Insects constitute an integral part of socio-cultural life of ethnic people in study areas. This book explains the collection and processing of red weaver ants in detail for consumption as delicious food as well as medicine. Red weaver ants are utilized for varied purposes, notably for food, medicine and hence support the livelihood of indiginious tribes here. Red weaver ants have long been used in traditional medicine to treat a vareity of ailments like cold, whooping cough, high fever, malarial fever, ear pain, etc. Even while scientific research on red weaver ant (O. smaragdina) in terms of pharmacological and nutritional evaluation is still lacking, it is the need of the hour
Chapter
Globally, 1.5 billion people use or trade non-timber forest products (NTFPs) with the majority of NTFP use and trade occurring at local and regional scales, generally invisible to researchers and policy makers. NTFPs cannot be measured by monetary estimations alone, as they have significant subsistence and sociocultural importance and are commonly one part of multifaceted, adaptive livelihood strategies. In spite of low-cost substitutes, both rural and urban people continue to use select forest resources for medicine, crafts, rituals, and food. And as drought, disease, famine, and conflict escalate globally, growing numbers of displaced and marginalized people depend upon forest resources for survival. In general, forests managed for timber and NTFPs retain more biodiversity and resilience than forest plantations or forests managed for industrial timber. Forests that harbor NTFPs also protect ecosystem services such as hydrological functions and soil retention and act as a buffer against climate variability. Land use change through logging, fire, and agribusiness is contributing to the degradation of forests, resulting in declining access to NTFPs for local communities. Land stewards can mitigate detrimental impacts to NTFPs by employing multiple-use management practices that emphasize ecosystem services and community needs in addition to traditional forestry outputs (timber and non-timber). For multiple-use forestry to be applied broadly, forest policies need to be cross-sectoral and scale sensitive to lessen regulatory obstacles for small holders and for common pool/property systems. In addition, forestry training needs to include a stronger social focus and improved understanding of the ecology, use, and societal and ecosystem service values of NTFPs.
Article
Full-text available
Weaver ants (Oecophylla spp.) are intensively studied in basic and applied contexts. Yet, little is known about their mating behavior. Knowledge on their reproductive strategy is a prerequisite to the basic understanding of their life history and may provide valuable information facilitating their use in integrated pest management (IPM) and protein production (entomophagy). Here, we report on the behavior displayed by O. longinoda in relation with their nuptial flights in Tanzania and test for environmental cues that may trigger the flights. Based on observations of 56 flights recorded over 2 years, we found that sexuals aggregate on nest surfaces prior to flights. We also found that flights took place during the raining season, and all flights took place in evenings just before sunset. Further to these, days with flights were associated with higher relative humidity and less sun shine compared to days without flights. Also, flights mainly took place around full moons. However, this correlation was based on a total of only five full moon phases and should, therefore, be interpreted with caution. The results also showed that flights were only significantly correlated with weather parameters during the early part of the mating season, the trend changed thereafter probably due to depletion of sexuals in the nests as the season progressed. This information improves our understanding of ant nuptial flights and offers a tool to improve forecasts of O. longinoda flights, enabling easier collection of mated queens to stock ant nurseries that supply ant colonies for IPM-programs.
Chapter
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The Asian weaver ant (Oecophylla smaragdina) larvae and pupae are collected in the wild from trees and commercialised as songbird food and fishing bait in Java, Indonesia. The produce called kroto brings substantial income to numerous rural households throughout the year. The resource's durability is until now ensured by the species' distribution (various ecosystems and polycalic structure of the nests), the constraints for collection (inaccessibility of small nests and ants' aggressive behaviour) and the limited number of collectors. However, constraints related to storage and transportation of the resource, retailer's margins and a policy on animal trade (i.e., birds) are limiting the benefits of commercialisation for collectors.
Article
Full-text available
We report numerous cases of capture and/or retrieval of very large prey by workers of the African weaver ant, Oecophylla longinoda (Latreille 1802), observed in Cameroon, Nigeria and Zaire. We describe also the remains of vertebrate prey found in the nests of O. longinoda in South Cameroon. Retrieval of large prey was exclusively observed in workers of large, mature colonies of O. longinoda, occupying solitary trees or bushes or groups of trees. As a rule, large prey were transported whole. As demonstrated by field and laboratory tests, O. longinoda capture large insects most efficiently while hunting in the manner of army ants. The arolia on the feet of workers of O. longinoda are of crucial importance for the success of capture and transport of large prey. Previously, retrieval of vertebrate prey was reported only in the Asian weaver ant species, O. smaragdina (Fabricius 1775). Our observations provide an account of some of the most striking cases of individual and cooperative transport of large objects ever observed in ants.
Article
Full-text available
Oecophylla ants utilize living leaves when they construct their nests. We investigated how Oecophylla smaragdina nests in southern Thailand affected leaf performance on the mangrove tree Rhizophora mucronata. Leaves used in nests and neighboring leaves showed a higher rate of premature leaf loss compared to control leaves farther from the nests. However, a tree's total cost due to the higher premature leaf loss was estimated to be approximately between 3- and 20-fold lower than the benefit derived from ant protection, detected in a previous study (Offenberg et al. 2004).
Article
The behavioral organization of territoriality in the green tree ant (Oecophylla smaragdina) was studied in the field of North Queensland, Australia. The establishment and maintenance of territories in O. smaragdina is based on a complex behavioral communication repertory which appears to be almost identical to that of its only living congeneric species, the African weaver ant O. longinoda. In our study areas, individual territories sometimes covered an area of up to 1500 m2 comprising 21 major trees. The polydomous nest organization makes it possible for an Oecophylla colony to patrol and crop much of the volume of the territory in a very cost efficient way. The guard and defense force which consists primarily of old workers with reduced fatbodies and ovaries, is housed in special barrack nests, located at the territorial boundary. A selective "enemy identification" seems to be the major behavioral mechanism for interspecific territoriality and for the mosaic distribution of ecologically dominant ant species.
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Following a questionnaire survey and field studies, the weaver ant, Oecophylla smaragdina (Fab.), was found to inhabit much of the coastal area of tropical Australia. With discriminant analyses, the observed distribution pattern was explained by the combination of two physical parameters, mean annual rainfall and average minimum temperature. These may limit Oecophylla distribution in at least two ways: (1) low temperatures directly inhibit larval development; (2) both rainfall and temperature levels limit the distribution of the forest-woodland vegetation required by this arboreal ant.
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Summarizes relevant aspects of ants' feeding habits and general ecology, followed by discussion of beneficial species and their attributes, and of how ecological conditions favoring their use can be manipulated for improved pest management. The stability, social organization, and foreging behavior of some predatory ants enable them to react quickly to increasing prey density, and also make them uniquely able to protect crops from low-density pests. Such qualities require dependence on honeydew-producing Homoptera that may sometimes be made harmful by ant attendance. Cost-benefit judgements are therefore needed when such ants are to be used. Predacious ants also affect other natural enemies, but less than might be expected, and may indeed benefit some. Ants tend to overlap the food niches of other predators and may force them into one competitive system. Whether overall biological control is benefited by such interactions is unknown. -from Authors
Article
Ants are well known for their complicated social organization, their altruistic behavior, and their impact on the terrestrial environment. Many published papers have reported their use as biological control agents. For example, the use of the weaver ant, Oecophylla smaragdina, for control of insect pests of citrus in ancient China was recorded as early as 304 A.D. in a work on regional botany, called Nan Fang Cao Mo Zhuang (Plants and trees of the southern region) by Ji Han. Since then the use of weaver ants, Polyrhachis vicina, Oecophylia smaragdina, and the pavement ant, Tetramorium bicarinatum (T. guineense), for plant protection in China has been referred to occasionally by entomologists (Doutt 1964; Konishi and Ito 1973; Simmonds et al 1976; Huang and Yang 1987; Li and Chen 1992). However, the fact that ants are commonly used as food and medicine throughout China is very poorly documented (Li and Chen 1992). This article describes the ancient and recent practice of using ants as food and of the use of ants as a medicine in treating various kinds of illnesses in China. Thus, while Berenbaum (1993) warns against eating insects that might have ingested toxins from plants, this article shows that ants may contain materials beneficial to human health as well as being a food item. Some of the situations described are not scientific, but are presented here so you might gain some insight into the use of ants in China.
Article
Fierce boundary fights between Oecophylla smaragdina colonies were previously identified as the major factor limiting ant populations and the efficiency of ants as biological control agents. In order to determine the feasibility and effect ofpreventing boundary fights between colonies, experiments with full-, semi- and no-isolation of existing antcolonies in cashew plantations were done in 1996 and 1997. In a related experiment, ant colonies were transplanted from native vegetation to a cashew orchard. Trees with ant colonies which were fully isolated from other colonies were significantly less damaged by the main insect pests and produced significantly higher yield than those with ant colonies which were partly isolated or were not isolated. That was because fighting events between fully isolated ant colonies were eliminated, and the populations of these colonies were high throughout the cashew flowering and fruiting period. Trees in which O. smaragdina colonies were transplanted suffered little damage by the main insect pests and produced high quality nuts and panicles. However, trees which were protected by pesticides produced lower quality nuts and panicles, because these trees suffered damage by the tea mosquito bug, Helopeltis pernicialis, and the mango tip borer, Penicillaria jocosatrix . It is suggested that O. smaragdina colony isolation, combined with ant transplantation, is an effective means both to achieve high ant populations in cashew plantations and to obtain a high yield.