Annals of Sri Lanka Department of Agriculture 2017. 19: 104 - 111

TERMITICIDAL ACTIVITY OF BIFENTHRIN AND FIPRONIL AGAINST MOUND BUILDING REDEMANNI WASMANN

N.K. HAPUKOTUWA1 AND S. PERERA2

1 Plant Protection Service, Gannoruwa, Sri Lanka 2 Plant Protection Service Subunit, Bombuwala, Sri Lanka

ABSTRACT

Bifenthrin 10% SC (Maxxthor) and Fipronil 25% EC (Premise) obtained from two new sources were tested during 2014 to determine their termiticidal activity against the mound building termite Odontotermes redemanni Wasmann. Termitariaat open landscape in School of Agriculture, Kundasale, Kandy was randomly as the source of termite. Two new chemicals (Maxxthor and Premise), two reference chemicals (Biflex® and Agenda®) and water (control) were used as treatments with three replicates. Tendried sticks (60 cm long and three cm diameter) of Kapok (Ceibapentandra) were treated and inserted into each termitarium allowing the to feed on. Sticks were removed at two time intervals: four and eight weeks and weighed separately to measure the wood consumption. Analysis of variance showed highly significant differences (p=0.0001) in wood consumption among the treatments: chemicals and water treated termitaria. Maximum wood consumption (88.4g/8 weeks) was recorded in water treated termitaria. However no significant difference in wood consumption was observed between chemically treated termitaria. Both chemicals irrespective of their active ingredients, formulation or country of origin, performed equally against O. Redemanni revealing that they are appropriate termiticides to control mound building termite problem in Sri Lanka.

Key words: Chemical control, Termites, Termitaria, Termiticide, wood consumption.

INTRODUCTION

Termites are abundant and diverse throughout the world (Donald and Dweight, 1970; Maayiem et al., 2012). Over 2,600 termite species have been identified worldwide (Resh and Carde, 2003). Of these, less than three percent is considered as economically significant pests. Sixty four extant species belongs to 27 families and four genera are found in Sri Lanka (Hemachandra TERMITICIDAL ACTIVITY OF BIFENTHRIN AND FIPRONIL 105

et al., 2012). Among the six Odontotermes species present in Sri Lanka, five are regionally distributed. The sixth, the mound building termite, Odontotermes redemannin Wasmann, a serious threat to wooden structures and a pest of tea, and sugarcane, has an Island wide distribution (Hemachandra et al., 2012). They also destroy the scenic beauty of garden landscapes by building termitaria. Further this species is one of the commonest mound-building termites in Sri Lanka (Ranaweera, 1962).

Termites cause millions of dollars’ worth of damage annually all over the world and no pest is more complicated to eradicate than termites. In general different cultural and chemical methods are used to control them. Some of the cultural methods are destruction of termitaria, removal of queen, flooding of termitaria and use of hot ash (Tasisa and Gobena, 2013). Most of these cultural methods are not highly effective compared to chemicals. Currently, synthetic insecticides (termiticides), plant extracts with insecticidal properties, bio-insecticides etc. are used as liquids, baits or any other forms to control termites.

Termiticides have special mechanisms that collapse whole colonies. Termites groom each other and share food by both orally and anally. They contact soil with their tarsi and body surfaces and also manipulate and carry soil particles in their termitaria as they dig tunnels. Thus, chemicals move from direct penetration of the cuticle or invasion via body openings. Chemical control of termites is expensive and requires skilled labour (Logan et al., 1990). Excess application of termiticides causes environmental pollution and may cause the death of non-target organisms (Dennis, 1987).

Termites cause serious damage to agriculture and construction industry in Sri Lanka. Hence, there is a critical need to find solutions to eradicate termites. Furthermore, only a very few termiticides are available in Sri Lanka. Fipronil and Bifenthirn are two of the most effective termiticides available. Fipronil is a broad-use insecticide that belongs to the phenylpyrazole chemical group. It disrupts the central nervous system by blocking GABA-gated chloride channels and glutamate-gated chloride (GluCl) channels. Fipronil is a slow-acting poison. When used as bait, it allows the 106 Hapukotuwa and Perera

poisoned insect to return to the colony or harborage. Bifenthrin is a pyrethroid insecticide. It mainly influences the nervous system of . The objective of this study was to evaluate two new termiticides (Bifenthrin 10 % SC and Fipronil 25 % EC) in order to select the more effective chemicals.

MATERIALS AND METHODS

Test termiticides, Bifenthrin10%SC and Fipronil 25% EC were evaluated in selected termitaria at School of Agriculture in Kundasale, Kandy; from October 13, to December 10, 2014. Five major plots were maintained, each with three replicates (Table 1) using randomized block design. Termite damage was assessed through visual observation and dry weight (feeding loss) of wood sticks. Kapok (Ceiba pentandra) wood was selected due to high termite preference. Each plot contained 10 wood sticks (60 cm long, oven dried (101 0C), weighed and labelled from 1-10). Half of the stick was inserted into termitaria through air vents (Figure 1). The test and reference termiticides were applied using a knapsack sprayer into each termitarium using recommended volumes. All termitaria were covered with polythene, after treatments, to protect from rain and to avoid other disturbances. A control termitarium, without any termiticides, was also maintained adjacent to treated termitaria.

Table 1. Experimental Setup.

Plot Number of Chemicals Rates of application (l/m2) replicates Test 1 3 Bifenthrin 10% SC (Maxxthor) 5 [diluted solution (50 ml into 10 l water)] Test 2 3 Fipronil 25% EC (Premise) 4-5 [diluted solution (125 ml into 10 l water)] Reference 1 3 Bifenthrin 100 EC (Biflex®) 5 [diluted solution (50 ml into 10 l water)] Reference 2 3 Fipronil 25% EC (Agenda®) 4-5 [diluted solution (125 ml into 10 l water)] Control 3 Only water 10 (water)

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Figure 1. Left: Termitaria after applying wooden sticks; Right: Spraying chemicals to selected termitaria

Every week, a few wood sticks were observed visually to check for damage caused by termites. After four weeks, five wood sticks were removed and oven dried for three days (due to heavy rain all sticks were heavy and contained large amounts of water). Dry weight of all removed sticks was measured. After eight weeks (from the date of initiation) rest of the wood sticks were removed, oven dried and weighed using a digital scale. Data were analyzed using SAS version 9.3 and Duncan’s Multiple Range Test (DMRT) was used for mean separation.

RESULTS AND DISCUSSION

High termite damage and feeding losses were visually observed in control termitaria (Figures 2 & 3). Termite damage increased with the time. This difference may be due to the changing weather conditions because damage caused by termites is greater in drought weather than in rainy weather (Logan et al., 1990; Nyeko and Olubayo, 2005). In the present study it was assumed that the relationship between termite density and feeding loss in all colonies were more or less equal.

We also observed significant differences of weight loss between control and treated samples which were taken at four and eight weeks after treatments. Observations made after eight weeks showed high mean values of weight loss in all treated and control plots compared to mean weight loss values made after four weeks. However, control plot showed the highest mean weight loss values compared to all treated plots (Table 2, Figure 2). 108 Hapukotuwa and Perera

Table 2. Mean weight loss values (g) after four and eight weeks.

Plot Chemicals Mean weight loss (g) Mean weight loss (g) (after four weeks) (after eight weeks) Test 1 Bifenthrin 10% SC 0.7 b 1.7 b (Maxxthor) Test 2 Fipronil 25% EC 0.6 b 0.9 b (Premise) Reference 1 Bifenthrin 100EC 1.3 b 1.9 b (Biflex®) Reference 2 Fipronil 25% EC 1.6 b 3.0 b (Agenda®) Control N/A (water) 37.8 a 88.4 a Note: Means within columns followed by the same letter are not significantly different according to the DMRT test at 5% probability

Results indicated that all tested termiticides significantly (p = 0.0001 / CV 33.82) reduced the termite damage of wood sticks compared to control. However, there were no significant differences were observed among chemical treatments (Table 2).

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Figure 2. Mean weight loss (g) of wood sticks after four and eight weeks of treatments.

Figure 3. Left: Treated wood sticks showing less damage; Right: untreated wood sticks showing more damage.

Treatments to termite mounds with chemicals have long been recognized as an appropriate mode of termite control because it creates a chemical barrier to exclude termites (Jones, 2003). Chemicals with two modes 110 Hapukotuwa and Perera

of actions are commonly used in termite control as repellents and non- repellents. In the past, repellent termiticides have been the principle approach used against termites. Fipronil25% EC (Agenda®) is a recommended termiticide in Sri Lanka and has faster killing action (Yeoh and Lee, 2006). Bifenthrin100 EC (Biflex®) is considered as a repellent termiticide with high termite mortality (Manzoor et al., 2012). However, both have their own pros and cons. A termiticide with killing action (non-repellent) allows termites to enter into treated soil (Thorne and Breisch, 2001). However, with sufficient toxicity it could kill any termite that comes in contact with the soil before it can cause the damage. Repellent termiticides, on the other hand, prevent termites from acquiring lethal doses, reducing termite mortality in spite of any toxicity (Smith and Rust, 1990).

CONCLUSION

Both chemicals tested (Bifenthrin10 % SC (Maxxthor) and Fipronil 25 % EC (Premise), irrespective of their formulations or sources are equally effective as Bifenthrin100 EC (Biflex®) and Fipronil25% EC (Agenda®) and can be used to control mound building termites in Sri Lanka. Rates of applications are 5 l of diluted solution into 1 m2 and 4-5 l of diluted solution into 1 m2. Since these chemicals possess different modes of action against termites, alternative use of both chemicals is advisable.

ACKNOWLEDGEMENTS

Authors wish to express their sincere thanks to Mr. H.N.P. Wijeyagunasekara (Retired Senior Lecturer, Faculty of Agriculture, University of Peradeniya) for improving research protocol and for his valuable comments on the manuscript. Special thanks are also due to Mr. K.P. Somachandra (Deputy Director, Regional Agricultural Research and Development Centre, Bandarawela) for his help in analyzing results and for his valuable suggestions for the improvement of the research protocol.

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