Variation of Food Preference of Black Ants (Dolichoderus thoracicus)

Smith and Four Antagonistic Ants in Cocoa Plantations in Indonesia

Ahmad Saleh

, Abu Hassan Ahmad

and Che Salmah Md. Rawi

College of Agricultural Sciences Agrobisnis Plantation (STIPAP), Jl. Willem Iskandar Medan

School of Biological Sciences, Universiti Sains Malaysia (USM), Penang, 11800 Malaysia

www.stipap.ac.id

Keywords: Dolichoderus thoracicus, antagonistic ants, food preference, cocoa pod borer

Abstract: This study was carried to determine the variation of food preferences of black ant, Dolichoderus thoracicus

Smith, and four antagonistic ants; Oecophylla smaragdina (Fabricius), Anoplolepis gracilipes (Jerdon),

Techonomyrmex sp. (Smith) and Crematogaster sp. (Smith), (Formicidae: Hymenoptera) in cocoa plantations.

Black ant is used in controlling cocoa pod borer (CPB). However, in carrying this biological control of CPB,

antagonist ants caused difficulty in establishing black ants. Naturally, black ants are attracted to honeydew

produced by mealybug (Cataenococcus hispidus). Six variations of food preference were tested i.e; honey,

dried salted fish powder, sugar powder, dried egg powder, syrup, and water. Dolichoderus thoracicus, O.

smaragdina and Crematogaster sp. preferred salted fish and egg powder while A. gracilipes preferred honey

and syrup and Techonomyrmex sp. preferred sugar powder and honey. The food preferred by antagonists can

be used as the components of incoporated into the toxic bait in controlling these ants. Baiting is an efficient

method of controlling the antagonistic ants, however, the black ant, D. thoracicus, also consumed similar food

as the antagonist ants. From the study, salted fish and egg powder could be made as an alternative food of D.

thoracicus if the cocoa plantations lack mealybugs.

1 INTRODUCTION

Black ants (Dolichoderus thoracicus Smith)

(Hymenoptera: Formicidae) have been known as biological

agents in controlling Cacao Pod Borer, Conopomorpha

cramerella Snellen (Lepidoptera: Gracillariidae) in a cocoa

plantation in Indonesia (Kalshoven, 1981; Ho, 1994; Saleh,

2011,). Cocoa Pod Borer is difficult to be controlled due to

the larvae ± 60% of its life cycle is in a cocoa pod and the

impact is the cocoa production reduce more than 80%

(Wardojo, 1980). High black ant populations are required

in controlling attacks of cocoa pod borer (Saleh, 2007).

Ants are one of the dominant communities of cocoa fauna

(Azhar, 1985). They have been reported to influence the

cocoa fauna structure and can be used a control agent for

some of the cocoa pests (Entwistle, 1972; Azhar, 1985).

There are more than 16 species of ant found in a cocoa

plantation in Bah Lias Estate, (Saleh, 2011). However, four

species are considered serious antagonists to D. thoracicus.

There are weaver ants or green tree ants, Oecophylla

smaragdina (Fabricius); long-legged ant, Anoplolepis

gracilipes (Jerdon); white-footed ant, Techonomyrmex sp

(Smith) and acrobat ant, Crematogaster sp (Smith). They

belong to Order Hymenoptera in the Family of Formicidae

(Khoo & Chung, 1989; Saleh et al. 2007). Based on their

dominance, these ant species prefer to inhabit in cocoa

plantations (Saleh et al. 2007; Anon. 2009). These

antagonist ants compete for the foods and aggressive to

drive out black ant from their territories (Entwistle, 1972).

Nevertheless, the weaver ant, O. smaragdina, is a useful

predator for controlling H. theobromae and others pests on

cocoa trees; however, it is not acceptable in IPM

management of cocoa pests because it inflicts painful bites

to workers in cocoa plantations and (Way & Khoo, 1991).

Areas to be established with D. thoracicus must be free

or a few population of antagonistic ants. Suppression of

antagonist ants is needed in the establishment of black ant,

especially in new areas (Entwistle, 1972; Saleh et al. 2006;

2007). Three out of four antagonist ants (O. smaragdina, A.

gracilipes and Technomyrmex sp) are severe prevent the

establishment of black ant. Practice in the estate, ant

antagonists are controlled by the application of Fipronil

insecticide (Saleh. 2011; Saleh et al. 2006; 2007). The

future control of antagonistic ants could be baiting method

which safe to human and cocoa environment. Ants that nest

in protected harborages are often unaffected by sprays but

will emerge from cryptic, protective habitats to feed on

toxic baits. Baits are easy to apply and require no mixing by

the applicator. Baits do not unduly affect non-target insect

species that are not attracted to the bait matrix, and they can

Saleh, A., Ahmad, A. and Md. Rawi, C.

Variation of Food Preference of Black Ants (Dolichoderus thoracicus) Smith and Four Antagonistic Ants in Cocoa Plantations in Indonesia.

DOI: 10.5220/0010036000050009

In Proceedings of the 3rd International Conference of Computer, Environment, Agriculture, Social Science, Health Science, Engineering and Technology (ICEST 2018), pages 5-9

ISBN: 978-989-758-496-1

be placed in containers which only allow access to target

species (Warner. et. al. 2004).

The objectives of the study were to determine the food

preference of the antagonistic ants and will not impact to D.

thoracicus population.

2 MATERIAL AND METHODS

The studies were conducted in June 2006 to December 2007

in the cocoa plantation located in Bah Lias Estate

PT.PP.London Sumatra Indonesia Tbk (Lonsum). Bah Lias

Estate is located at 99° 15’ 36” - 99° 21’ 36” East and 3° 8’

24” - 3°13” 12” North, in the province of North Sumatera,

Indonesia. The altitude of Bah Lias Estate is 32 m above sea

level and the distance from Medan is 139 km. The average

rainfall at Bah Lias Estate in 2006 and 2017 were 1940 and

1502 mm, with 113 and 94 rain days/ year (BLRS. 2006.

2007). The 26-year-old cocoa field which consists of 700

trees and 50 coconut palms as permanent shade per ha was

chosen for this study area. The D. thoracicus ant was not

establish for all area and some plots of areas were occupied

by antagonistic ants. For this study, a plot for each kind of

ants was 400 trees (20x20) which occupied by O.

smaragdina, A. gracilipes, Techonomyrmex sp and

Crematogaster sp, then selected 5 trees sample/plot for

placing the food preference.

This study was to determine the kinds of foods

preference for 4 antagonistic ants (including Crematogaster

sp).

The six kinds of foods attractant were tested i.e; honey,

dried salted fish powder, sugar powder, dried eggs powder,

syrup, and water. The powder of salted fish and sugar and

chicken egg were dried under the sun for few days before

use and Solution of 10% honey bee and Syrup Kurnia

(contains; sugar, citric acid, Karmoisi Cl 14720 and

Raspberry aroma, (Syrup. 2014).

Twenty g powder of salted fish, sugar and eggs and 20

ml for the solution of honey and syrup were prepared and

placed in a Petri dish of 3.7 cm diameter and 1.0 cm high

and then each Petri dish was placed in a larger Petri dish,

9.3 cm diameter and 0.7 cm height.

The experiment design was use Randomized Block

Design with five replicates (5 trees were selected in each

plot) and six treatments (food preference) for each kind of

ants.

The bait (food preference) were placed on the ground

10 - 20 cm from the base of each of their trunks as shown

in Figure.1.

Figure 1. Food baits are placed on ground 10- 20 cm from

the cocoa trunk.

The population of ants was counted monthly during the

observation. The observation started at 07.00 hr and ended

at 13.00 hr. There were six hourly observations in each

month. At the end of each hour, the Petri dishes were

collected and placed separately in a plastic bag and the ants

were killed, and all foods were replaced hourly. Then the

number of antagonist ants found in the Petri dish was

counted in the laboratory. The mean number of ants on each

food was analyzed by using one-way ANOVA with SPSS

22 program.

3 RESULTS

The result of determinating the variation of food preference

the black ant and antagonistic ants from June 2006 to

December 2007 as shown in Table 1.

Table.1. Food preference of D.thoracicus and its antagonists

Food preference Mean ± SE of ants per bait

A. gracilipes Crematogaster O. smaragdina Technomyrmex sp D. thoracicus

Honey 24.9 ± 1.7 b 3.3 ± 0.3 de 2.1 ± 0.0 d 26.9 ± 1.2 b 13.1 ± 0.6 d

Salted fish (*) 4.8 ± 0.4 d 53.9 ± 4.7 a 15.0 ± 0.3 a 21.5 ± 1.4 c 137.2 ± 2.2 a

Sugar (*) 16.6 ± 1.8 c 10.5 ± 0.5 cd 1.8 ± 0.1 de 41.6 ± 1.1 a 29.7 ± 1.4 c

Eggs (*) 4.0 ± 0.3 d 28.3 ± 1.9 b 12.3 ± 0.5 b 15.3 ± 1.0 d

81.6 ± 4.3 b

Syrup 43.9 ± 1.9 a 12.6 ± 0.9 c 3.8 ± 0.3 c 41.2 ± 1.0 a 27.0 ± 2.1 c

Water 0.8 ± 0.0 d 0.5 ± 0.1 e 0.4 ± 0.0 e 1.4 ± 0.2 e 1.9 ± 0.1 e

Means in the same column followed by a different letter are significantly different (LSD test, P = 0.05).

ICEST 2018 - 3rd International Conference of Computer, Environment, Agriculture, Social Science, Health Science, Engineering and

Technology

Figure 2: Variation of Food Preference of D. thoracicus and antagonistic ants

Table 1 and Figure 2 indicate that A. gracilipes preferred to

consume syrup, honey and sugar powder than salted fish

powder, egg powder, and water. Statistically, these

preferences were significantly different (F=138.9; P <

0.001). Among the three most preferred food, A. gracilipes

preferred syrup the most. Crematogaster sp strongly

preferred salted fish and eggs powder continuously as

depicted and significantly different to others food (F=

108.7; P < 0.001). O. smaragdina showed a strong

preference for powder of salted fish and followed by egg

powder and other food types such as syrup, honey and sugar

powder (F= 466.2; P < 0.001). Technomyrmex sp preferred

to eat with a similar amount of sugar, and syrup then

followed by honey, salted fish and egg powder. These food

preferences were significantly different (F= 290.7; P <

0.001). The alternative of food preferred by D. thoracicus

was salted fish powder followed by egg powder and honey.

They were statistically significantly different to sugar

powder and syrup and control (water) (F= 573.2; P <

0.001).

4 DISCUSSIONS

In natural the long-legged ants, A. gracilipes feed on

honeydew from coccid, jassids, and mealybugs (Entwistle,

1972; Kalshoven, 1981), and the result of this study

indicated that A. gracilipes preferred to consume syrup,

honey. There are sometimes aggressive towards other ant

species such as the useful black ant (D. thoracicus) in cocoa

capturing individuals of the latter species and spraying them

with formic acid. The presence of the long-legged ant in

cocoa, unlike black ant, does not favor the white mealybugs

(Entwistle, 1972; Kalshoven, 1981).

Day (1986) and (Kalshoven, 1981) said that for

Crematosgaster habitually feeds on the sugary substances

produced by sucking insects and plants, on animal refuse

and are occasionally carnivorous, while this study

Crematosgaster consume more salted fish and egg powder.

In actual O. smaragdina feed on the honeydew from

coccids, Membracidae and Lycaenidae, moreover, they

feed on dead animal material and attack living insects

(Kalshoven, 1981). It is mostly similar to the result of this

study that its preference the salted fish and egg powder.

Techonomyrmex feeds on plant nectars and honeydew,

which is a sweet substance produced by many sap-sucking

insects such as aphids, mealybugs, and scales, and it is

known to protect honeydew producers, which has caused

problems in agricultural production in some areas of the

world (Warne, et al. 2016). Food of D. thoracicus, black

ant is largely derived from the honeydew of its mutualism,

the mealybug, C. hispidus (Ho & Khoo, 1997). Species of

mealybugs attended by D. thoracicus include

Cataenococcus hispidus, Planococcus lilacinus,

Pseudococcus elisae, and Maconellicoccus hirsutus (Khoo

& Chung, 1989). The black ant also regularly tend the long-

tailed mealybug of cocoa (Planococcus lilacicus), the green

scale (Coccus viridis), the whitefly of jambu (Psidium

guajava), some small tree hoppers (Membracidae) and

Psyllidae (Kalshoven, 1981; Azhar, 1988). Kalshoven

(1981) added that besides attending the mealybugs, black

ants also feed on nectar which produced by flower resinous

secretion of bamboo, pollen and fungal fructification. It has

been observed that when the mealybug of cocoa is scarce,

the black ants also feed on the peel of the fruits of a small

weed, wellcresses (Paperomia pellucida) (Kalshoven,

1981). It is known that the presence of the ants favors the

development of white cocoa mealybugs (the survival of

these coccids may depend on the ants) and that of green

coccid. The mealybugs (which cover the colonies with the

papery material) are protected by ants (Ho & Khoo, 1997;

Khoo & Ho, 1992; Azhar, 1994).

Baiting is one of the effective control methods widely

used in ants, such as yellow crazy ant (long-legged ant),

white food ant and acrobat ants (Abbott et al. 2009; Harris,

Variation of Food Preference of Black Ants (Dolichoderus thoracicus) Smith and Four Antagonistic Ants in Cocoa Plantations in Indonesia

2009). However, Warner (2003) said that the main

requisites for a successful ant bait are 1) Preferred bait base

must endure long enough to achieve control, 2) Non-

repellent active ingredient, 3) Active ingredient must acts

slow enough to circulate within the colony and/or to allow

the recruitment of new foragers, 4). Active ingredient must

be transferable to nestmates and brood, and 5) Has low

mammalian toxicity.

Using baits to control antagonistic ants in the sporadic

areas where black ant, D. thoracicus has established well

must be carefully decided because the food preference for

bait materials will be consumed by black ant. This can be

disastrous to the black ant population later on. This study

indicates that some the food preferred by antagonistic ants,

A. gracilipes and Technomyrmex sp, were similar, namely

syrup and sugar powder, while Crematogaster sp. and O.

smaragdina preferred the powdered salted fish and egg,

which was also preferred by D. thoracicus. However, D.

thoracicus consumes all of the food preference are tested.

The life history of A. gracilipes this species in detail, since

it plays an important role in tending pests such as

mealybugs, scales and jassids, unlike the black ant (D.

thoracicus), this species is therefore considered to be a pest

of several crops, such as coffee, cocoa, mango, etc (Saleh,

2011).

5 CONCLUSIONS

Salted fish and egg powder are food preferenced by Black

ant (D. thoracicus), O. smaragdina and Crematogaster.

For A. gracilipes and preferred honey and syrup, while

Technomyrmex. sp preferred sugar powder and honey.

D. thoracicus consumes most all food is tested, in

consequence, Salted fish and others could be used for

alternative food when establishing of black ant especially if

the cocoa areas lack mealybug.

ACKNOWLEDGEMENT

The author is thankful to Head of College of Agricultural

Sciences Agrobisnis Plantation (STIPAP) to publish this

paper and provide needed facilities. And also thanks to Bah

Lias Research Station PT. Lonsum to help and give

facilities for this study.

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Variation of Food Preference of Black Ants (Dolichoderus thoracicus) Smith and Four Antagonistic Ants in Cocoa Plantations in Indonesia