SustainablyGrowing mahoganythe weaver ant, a biological control agent of mahogany pests augmentation...
1
sustainab ly Growing mahogany the weaver ant, a biological control agent of mahogany pests augmentati on conservat ion throug h and of Grace T. Lim 1&2 , Scott M. Salom 1 , Laurence G. Kirton 2 , Loke T. Kok 1 , 1 Entomology Dept, Virginia Tech, 2 Entomology Unit, Forest Research Institute Malaysia Introduct ion Mahogany is among the most valuable tropical hardwoods in the world and has been harvested to commercial extinction. Numerous reforestation efforts worldwide with mahogany species, e.g.,Swietenia macrophylla and Khaya ivorensis (Meliaceae) have been foiled by the mahogany shoot borers (Hypsipyla spp., Lepidoptera: Pyralidae) found throughout the tropics. Eight decades of research spanning 23 countries has yet to come up with a reliable, cost-effective and environmentally sound solution to this problem. Below L-R: The adult female lays eggs on a leaf axil or new shoot that a newly emerged larva will burrow into. The larva later migrates to the terminal shoot; which dies as the pith is consumed; and the tree develops multiple leaders as a result Hypsipyla robusta, the Shoot Attacker Oecophylla smaragdina, the Shoot Protector! The weaver ant, Oecophylla smaragdina (Hymenoptera: Formicidae), inhibits infestation of mahogany by the shoot borer, Hypsipyla robusta, which attacks mahoganies in Asia, Australia and the Pacific Islands. It is an aggressive predator of arthropods, including H. robusta (R). It vigilantly patrols its host plant, which includes K. ivorensis (L), building nests from young leaves. International collaborative research by Virginia Tech’s Entomology Department and the Forest Research Institute of Malaysia (FRIM) is currently focusing on conservation and augmentation as biological control approaches to enhance the performance of the weaver ant against the shoot borer. nes t • The ant also tends ‘trophobionts’, e.g.,mealybugs (Hemiptera), in exchange for ‘honeydew’ excreta, an important food of the ant. • The leaf nests of this ant can be ‘harvested’ from other trees and introduced to mahogany plantations to protect them. • Protection is needed for the first three years until an unbranched height of 8 m is achieved. Methods • Four Malaysian habitats, including mangroves (R), were surveyed for host plants of the ant. • All vegetation within 3 m of trail borders along a 1 km line transect was examined for weaver ant nests . Surveys for Host Plants of the Ant Results •Four host plant species were particularly ant- abundant: Morinda citrifolia (Rubiaceae), Talipariti tiliaceum (Malvaceae), Bruguiera spp. (Rhizophoraceae), Acacia auriculiformis (Fabaceae). Major Studies and Results Bluthgen, N. & Fiedler, K. 2004. Preferences for sugars and amino acids and their conditionality in a diverse nectar-feeding ant community. Journal of Animal Ecology 73:155-166. Griffiths, M.W. 2001. The biology and ecology of Hypsipyla shoot borers. Pp. 74-80 in Floyd, R.B. & Hauxwell, C. (Eds.). Proceedings of an International Workshop on Hypsipyla Shoot Borers in Meliaceae. ACIAR Proceedings Series No 97. Kandy, Sri Lanka, 20-23 August 1996. ACIAR, Canberra. Lim, G.T. & Kirton, L.G. 2003. A preliminary study on the prospects for biological control of the mahogany shoot borer, Hypsipyla robusta (Lep.: Pyral.), by ants (Hymen.: Form.). Pp. 240-244 in Proc. of Intern. Conf. on Forestry and Forest Products Research. Kuala Lumpur, 1-3 October 2001. FRIM, Malaysia. Way, M.J. & Khoo, K.C. 1991. Colony dispersion and nesting habits of the ants, Dolichoderus thoracicus and Oecophylla smaragdina (Hymenoptera: Formicidae), in relation to their success as biological control agents on cocoa. Bulletin of Entomological Research 81(3):341-350. Literature Cited We thank Ms. Saimas Ariffin, Mr. Saiful Azhari, Mr. Shaiful Amri, Ms. Nurziah Ishak, Mr. Fadir Ishak (below), Ms. Hidaya, and Mr. Azmi Mahyuddin (Entomology Section, FRIM) for assistance in conducting the experiments, and Dr Ang Lai Hoe (Ecophysiology Section, FRIM) for use of Hobos. The plant species were identified by Mr Mohd. Asri and Mr Kamarudin Saleh (Botany Section, FRIM). Identification of trophobionts was provided by M. Kosztarab (Virginia Tech) S.H. McKamey and D.R. Williams (USDA-ARS). Acknowledgements Morinda citrifolia (9.3 ± 4.7) Talipariti tiliaceum (1.3 ± 0.7) Bruguiera spp. (1.1 ± 0.5) Avicennia officinalis (0) -3 -2 -1 0 1 2 3 4 R elative ant abundance rank (K ruskal-W allisz- value) Plantspecies (Relative nestvolum e ± SEM , cm 3 m -3 , n = 4) Conclusion s Ants ! -5 0 5 10 15 20 Food W eightoffood taken (g) -5 0 5 10 15 20 W eightoffood taken (g) Choice Test No Choice Test (a ) (b ) Figs. 1.(a-b). The average amount of four foods taken daily by O. smaragdina in the choice test (left) and no-choice test.(right) (± SEM, n = 6 and n = 3 for the choice and no-choice tests, respectively) Assessing Food Preference of the Ant contr ol treatme nt stri ng nest •Data analysis: Kruskal-Wallis & Friedman’s tests Results •The ants preferred live mealworms (Fig 1.a) but accepted fish when no choice was given (Fig 1.b). •The ants did not consume much liquid food. Discussion •Established colonies may get enough honeydew from trophobionts but relocated colonies have few trophobionts and may need ‘high- carb’ supplemental foods. Thus, ‘high-carb’ weaver ant formula and ‘high-protein’ mealworms chosen for next study. Effect of Food Supplementation on the Ant A complementary series of studies was successfully conducted to conserve and augment weaver ant populations. Methods •12 ant colonies relocated to new mahogany host plants at FRIM. •Half the colonies received weaver ant formula and mealworms (L-R) for 16 weeks. •Ant activity monitored weekly on shoots, around the foods and in nest-building. •Data analysis: GLM ANOVA. Results and Discussion • Food-supplemented (F) colonies had greater colony sizes than the C colonies receiving no food. • For F colonies much weaver ant formula was consumed initially (wk 1-9) then declined while ant activity on shoots and nest-building increased. • F colonies may have ‘weaned off’ the foods after establishing. Screening Host Plant Candidates Methods •Three favored host plant species from the previous study were tested: M. citrifolia, T. tiliaceum and Bruguiera spp, plus non-host Avicennia officinalis (Acanthaceae) as the control. •Ant preference was evaluated using a ‘relative ant abundance index’, based on ratio of volume of nests : plant crown surface area. •Data analysis: Kruskal-Wallis test. Results and Discussion •The ant was most abundant on M. citrifolia, followed by T. tiliaceum and Bruguiera spp. (Fig 2. below). •Many ants aggregated on M. citrifolia fruit, imbibing nectar (R). Trophobionts tended by the ant on M. citrifolia posed no pest risk. •M. citrifolia was selected for next study. Fig. 2. Relative ant abundance in relation to three host plant species and one non-host plant species of O. smaragdina. Future Work A study is in progress to evaluate effects of mixed-planting M. citrifolia with mahogany on establishment of food-supplemented ant colonies (below). Please contact first author for additional information. E-mail: [email protected]. Campus address: 216 Price Hall, Blacksburg VA 24061 A weaver ant colony relocated to new host plants can be conserved and augmented in a ‘two-pronged’ approach: 1. Short term: Direct food supplementation to meet energetic needs until it is self- sufficient, i.e., has cultivated enough trophobionts. 2. Long term: Indirect food provision and additional nesting sites in a more stable and diverse mixed-plantation. Therefore, the objectives of this research program were to identify: 1. Preferred foods of the ant that aid colony conservation. These foods should be cheap and practical to apply. 2. A preferred alternate host plant species of the ant that can be easily grown with mahogany as a second crop. Rationale • Relocated weaver ant colonies can be conserved by short- term food supplementation • Live mealworms (L) and weaver ant formula are preferred foods that are cheap and simple to apply • Foods should be given for at least 3 months to ensure colony establishment • M. citrifolia is a preferred host plant of the ant that is easy to grow and yields profitable medicinal by- products. Methods •A choice and no-choice study used mature weaver ant colonies at FRIM •Choice test (R): 6 ant colonies had ad libitum access to 4 foods: fish, live mealworms, liquid ‘weaver ant formula’ (with body-building protein powder) and honey solution. Food amounts taken recorded daily for 7 d. •The no-choice test was similarly conducted, but gave only one of the 4 foods to a total of 12 colonies. Providing foods directly through supplemental feeding and indirectly by planting alternative host plants with the main crop may well prove to be a reliable approach to growing environmentally-friendly mahogany in partnership with the weaver ant. This project was supported by the Fulbright Program (administered by the U.S. Department of State, the Institute of International Education, and the Malaysian-American Commission on Educational Exchange), Virginia Tech and FRIM.
-
Upload
ellen-fowler -
Category
Documents
-
view
215 -
download
1
Transcript of SustainablyGrowing mahoganythe weaver ant, a biological control agent of mahogany pests augmentation...
sustainablyGrowing mahogany the weaver ant,a biological control agent of mahogany pests
augmentationconservationthrough and of
Grace T. Lim1&2, Scott M. Salom1, Laurence G. Kirton2, Loke T. Kok1,
1Entomology Dept, Virginia Tech, 2Entomology Unit, Forest Research Institute Malaysia
Introduction
Mahogany is among the most valuable tropical hardwoods in the world and has been harvested to commercial extinction. Numerous reforestation efforts worldwide with mahogany species, e.g.,Swietenia macrophylla and Khaya ivorensis (Meliaceae) have been foiled by the mahogany shoot borers (Hypsipyla spp., Lepidoptera: Pyralidae) found throughout the tropics. Eight decades of research spanning 23 countries has yet to come up with a reliable, cost-effective and environmentally sound solution to this problem.
Below L-R: The adult female lays eggs on a leaf axil or new shoot that a newly emerged larva will burrow into. The larva later migrates to the terminal shoot; which dies as the pith is consumed; and the tree develops multiple leaders as a result
Hypsipyla robusta, the Shoot Attacker
Oecophylla smaragdina, the Shoot Protector!
The weaver ant, Oecophylla smaragdina (Hymenoptera: Formicidae), inhibits infestation of mahogany by the shoot borer, Hypsipyla robusta, which attacks mahoganies in Asia, Australia and the Pacific Islands.
It is an aggressive predator of arthropods, including H. robusta (R).
It vigilantly patrols its host plant, which includes K. ivorensis (L), building nests from young leaves.
International collaborative research by Virginia Tech’s Entomology Department and the Forest Research Institute of Malaysia (FRIM) is currently focusing on conservation and augmentation as biological control approaches to enhance the performance of the weaver ant against the shoot borer.
nest
• The ant also tends ‘trophobionts’, e.g.,mealybugs (Hemiptera), in exchange for ‘honeydew’ excreta, an important food of the ant.
• The leaf nests of this ant can be ‘harvested’ from other trees and introduced to mahogany plantations to protect them.
• Protection is needed for the first three years until an unbranched height of 8 m is achieved.
Methods• Four Malaysian habitats, including
mangroves (R), were surveyed for host plants of the ant.
• All vegetation within 3 m of trail borders along a 1 km line transect was examined for weaver ant nests .
Surveys for Host Plants of the Ant
Results • Four host plant species were particularly ant-abundant: Morinda
citrifolia (Rubiaceae), Talipariti tiliaceum (Malvaceae), Bruguiera spp. (Rhizophoraceae), Acacia auriculiformis (Fabaceae).
Major Studies and Results
Bluthgen, N. & Fiedler, K. 2004. Preferences for sugars and amino acids and their conditionality in a diverse nectar-feeding ant community. Journal of Animal Ecology 73:155-166.
Griffiths, M.W. 2001. The biology and ecology of Hypsipyla shoot borers. Pp. 74-80 in Floyd, R.B. & Hauxwell, C. (Eds.). Proceedings of an International Workshop on Hypsipyla Shoot Borers in Meliaceae. ACIAR Proceedings Series No 97. Kandy, Sri Lanka, 20-23 August 1996. ACIAR, Canberra.
Lim, G.T. & Kirton, L.G. 2003. A preliminary study on the prospects for biological control of the mahogany shoot borer, Hypsipyla robusta (Lep.: Pyral.), by ants (Hymen.: Form.). Pp. 240-244 in Proc. of Intern. Conf. on Forestry and Forest Products Research. Kuala Lumpur, 1-3 October 2001. FRIM, Malaysia.
Way, M.J. & Khoo, K.C. 1991. Colony dispersion and nesting habits of the ants, Dolichoderus thoracicus and Oecophylla smaragdina (Hymenoptera: Formicidae), in relation to their success as biological control agents on cocoa. Bulletin of Entomological Research 81(3):341-350.
Literature Cited
We thank Ms. Saimas Ariffin, Mr. Saiful Azhari, Mr. Shaiful Amri, Ms. Nurziah Ishak, Mr. Fadir Ishak (below), Ms. Hidaya, and Mr. Azmi Mahyuddin (Entomology Section, FRIM) for assistance in conducting the experiments, and Dr Ang Lai Hoe (Ecophysiology Section, FRIM) for use of Hobos.
The plant species were identified by Mr Mohd. Asri and Mr Kamarudin Saleh (Botany Section, FRIM). Identification of trophobionts was provided by M. Kosztarab (Virginia Tech) S.H. McKamey and D.R. Williams (USDA-ARS).
AcknowledgementsMorinda citrifolia
(9.3 ± 4.7)
Talipariti tiliaceum (1.3 ± 0.7)
Bruguiera spp. (1.1 ± 0.5)
Avicennia officinalis
(0)
-3-2-101234
Relative ant abundance rank (Kruskal-Wallis z-
value)
Plant species (Relative nest volume ± SEM, cm3m-3, n = 4)
Conclusions
Ants!
-5 0 5 10 15 20
Food
Weight of food taken (g)-5 0 5 10 15 20
Weight of food taken (g)
Choice Test No Choice Test
(a)
(b)
Figs. 1.(a-b). The average amount of four foods taken daily by O. smaragdina in the choice test (left) and no-choice test.(right) (± SEM, n = 6 and n = 3 for the choice and no-choice tests, respectively)
Assessing Food Preference of the Ant
control
treatment
string
nest• Data analysis: Kruskal-Wallis & Friedman’s testsResults• The ants preferred live mealworms (Fig 1.a) but
accepted fish when no choice was given (Fig 1.b).• The ants did not consume much liquid food.Discussion • Established colonies may get enough honeydew
from trophobionts but relocated colonies have few trophobionts and may need ‘high-carb’ supplemental foods. Thus, ‘high-carb’ weaver ant formula and ‘high-protein’ mealworms chosen for next study.
Effect of Food Supplementation on the Ant
A complementary series of studies was successfully conducted to conserve and augment weaver ant populations.
Methods• 12 ant colonies relocated to new mahogany host
plants at FRIM. • Half the colonies received weaver ant formula and
mealworms (L-R) for 16 weeks. • Ant activity monitored weekly on shoots, around
the foods and in nest-building. • Data analysis: GLM ANOVA.
Results and Discussion• Food-supplemented (F) colonies had greater colony sizes than the C
colonies receiving no food. • For F colonies much weaver ant formula was consumed initially (wk 1-9)
then declined while ant activity on shoots and nest-building increased. • F colonies may have ‘weaned off’ the foods after establishing.
Screening Host Plant Candidates
Methods• Three favored host plant species from the previous study were tested: M.
citrifolia, T. tiliaceum and Bruguiera spp, plus non-host Avicennia officinalis (Acanthaceae) as the control.
• Ant preference was evaluated using a ‘relative ant abundance index’, based on ratio of volume of nests : plant crown surface area.
• Data analysis: Kruskal-Wallis test.
Results and Discussion• The ant was most abundant on M.
citrifolia, followed by T. tiliaceum and Bruguiera spp. (Fig 2. below).
• Many ants aggregated on M. citrifolia fruit, imbibing nectar (R). Trophobionts tended by the ant on M. citrifolia posed no pest risk.
• M. citrifolia was selected for next study.
Fig. 2. Relative ant abundance in relation to three host plant species and one non-host plant species of O. smaragdina.
Future Work
A study is in progress to evaluate effects of mixed-planting M. citrifolia with mahogany on establishment of food-supplemented ant colonies (below). Please contact first author for additional information. E-mail: [email protected]. Campus address: 216 Price Hall, Blacksburg VA 24061
A weaver ant colony relocated to new host plants can be conserved and augmented in a ‘two-pronged’ approach: 1. Short term: Direct food supplementation to meet energetic needs
until it is self-sufficient, i.e., has cultivated enough trophobionts. 2. Long term: Indirect food provision and additional nesting sites in a
more stable and diverse mixed-plantation.Therefore, the objectives of this research program were to identify:1. Preferred foods of the ant that aid colony conservation. These foods
should be cheap and practical to apply.2. A preferred alternate host plant species of the ant that can be easily
grown with mahogany as a second crop.
Rationale
• Relocated weaver ant colonies can be conserved by short-term food supplementation
• Live mealworms (L) and weaver ant formula are preferred foods that are cheap and simple to apply
• Foods should be given for at least 3 months to ensure colony establishment
• M. citrifolia is a preferred host plant of the ant that is easy to grow and yields profitable medicinal by-products.
Methods • A choice and no-choice study used mature weaver ant colonies at FRIM • Choice test (R): 6 ant colonies had ad libitum access to 4 foods: fish, live
mealworms, liquid ‘weaver ant formula’ (with body-building protein powder) and honey solution. Food amounts taken recorded daily for 7 d.
• The no-choice test was similarly conducted, but gave only one of the 4 foods to a total of 12 colonies.
Providing foods directly through supplemental feeding and indirectly by planting alternative host plants with the main crop may well prove to be a reliable approach to growing environmentally-friendly mahogany in partnership with the weaver ant.
This project was supported by the Fulbright Program (administered by the U.S. Department of State, the Institute of International Education, and the Malaysian-American Commission on Educational Exchange), Virginia Tech and FRIM.
