Termite genome lays roadmap for 'greener' control measures

May 20, 2014  


Michael Scharf termites

Michael Scharf eyes a group of eastern subterranean termites, destructive pests in Indiana and the Eastern U.S. (Purdue University photo / Tom Campbell)
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WEST LAFAYETTE, Ind. - A team of international researchers has sequenced the genome of the Nevada dampwood termite, providing an inside look into the biology of the social insect and uncovering new genetic targets for pest control.

Michael Scharf, a Purdue University professor of entomology who participated in the collaborative study, said the genome could help researchers develop control strategies that are more specific than the broad-spectrum chemicals conventionally used to treat termite infestations.

"The termite genome reveals many unique genetic targets that can be disrupted for better termite control," said Scharf, who is the O. Wayne Rollins/Orkin Chair in Molecular Physiology and Urban Entomology. "Depending on which gene or protein that is targeted, we could disrupt termites' neurological processes, molting, digestive factors or cuticle formation. We're just limited by our imagination."

The Nevada dampwood termite is the first termite species to have its genome sequenced. While dampwood termites do not cause significant damage to buildings, they are closely related to key pests such as the eastern subterranean termite, which is the main pest species in Indiana and the Eastern U.S.

Termites are major pests of human structures, costing an estimated $40 billion in damage and control treatment each year. Having the genome in hand will enable researchers to look for common features expressed across termite species to find control targets effective for all types of termites, Scharf said.

Current termite control measures consist largely of synthetic chemical-based products, some of which are toxic to vertebrates.

"While current pesticides are very effective products, the problem is that you're injecting large volumes of them into the soil around the house," Scharf said. "It would be nice to move to a greener technology, and that's what the genome sequence could enable us to do."

Baiting termites with small quantities of treated wood that they could eat and share with colony-mates would be one such technique, he said. Newer technology such as gene silencing, which targets termite RNA to reduce the expression of critical genes, could also knock out the pests.

"With termites, you don't have to impact all of them," he said. "Targeting just a fraction of the workers could cause an entire colony to collapse."

The study also highlights genes related to chemical communication, the way in which termites "talk" to one another to signal aggression or a desire to reproduce.

"There's a lot of social strife in a termite colony, and it's got to stay cohesive to survive," Scharf said. "Chemical communication is crucial to keeping the labor force in place."

The genome could also help researchers better understand the symbiosis between termites and the more than 4,000 species of bacteria that thrive in their guts, aiding in processes such as digestion and defense. Previous studies of the termite gut were hampered by the inability to distinguish between termite and microbe genes. Understanding the gut biology is important to Scharf, who is researching the enzymes that termites use to digest wood. Identifying these enzymes could lead to novel methods of producing cellulosic biofuels.

"The genome provides a well-defined roadmap that could help us find the right cocktail of enzymes to break wood down into its simple sugars," he said. "It takes a lot of the guesswork out."

The study was published in Nature Communications Tuesday (May 20).

Funding for the research was provided by a grant from the U.S. Department of Agriculture's National Institute of Food and Agriculture, the Deutschen Forschungsgemeinscharf and the Loewe Research Focus "Insect Biotechnology." 

Writer: Natalie van Hoose, 765-496-2050, nvanhoos@purdue.edu

Source: Michael Scharf, 765-496-6710, mscharf@purdue.edu


ABSTRACT

Molecular traces of alternative social organization in a termite genome

Nicolas Terrapon 1; Cai Li 2, 3; Hugh M. Robertson 4; Lu Ji 2; Xuehong Meng 2; Warren Booth 5; Zhensheng Chen 2; Christopher P. Childers 6; Karl M. Glastad 7; Kaustubh Gokhale 8; Johannes Gowin 9; Wulfila Gronenberg 10; Russell A. Hermansen 11; Haofu Hu 2; Brendan G. Hunt 7; Ann Kathrin Huylmans 1; Sayed M.S. Khalil 5, 12; Robert D. Mitchell 5; Monica C. Munoz-Torres 13; Julie A. Mustard 8; Hailin Pan 2; Justin T. Reese 6; Michael E. Scharf 14; Fengming Sun 2; Heiko Vogel 15; Jin Xiao 2; Wei Yang 2; Zhikai Yang 2; Zuoquan Yang 2; Jiajian Zhou 2; Jiwei Zhu 5; Colin S. Brent 16; Christine G. Elsik 6, 17; Michael A. D. Goodisman 7; David A. Liberles 11; R. Michael Roe 5; Edward L. Vargo 5; Andreas Vilcinskas 18; Jun Wang 2, 19, 20; Erich Bornberg-Bauer 1; Judith Korb 9; Guojie Zhang 2, 21; Jurgen Liebig 8

1 Institute for Evolution and Biodiversity, Westfalische Wilhelms-Universitat, Munster D48149, Germany

2 China National GeneBank, BGI-Shenzhen, Shenzhen 518083, China

3 Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Oster Voldgade 5-7, Copenhagen 1350, Denmark

4 Department of Entomology, University of Urbana-Champaign, Urbana, Illinois 61801, USA

5 Department of Entomology and W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina 27695, USA

6 Division of Animal Sciences, University of Missouri, Columbia, Missouri 65211, USA

7 School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332, USA

8 School of Life Sciences, Arizona State University, Tempe, Arizona 85287, USA

9 Behavioural Biology, University of Osnabruck, Osnabruck D49076. Germany

10 Department of Neuroscience, University of Arizona, Tuscon, Arizona 85721, USA

11 Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071, USA

12 Department of Microbial Molecular Biology, Agricultural Genetic Engineering Research Institute, Giza 12619, Egypt

13 Genomics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

14 Department of Entomology, Purdue University, West Lafayette, Indiana 47907, USA

15 Department of Entomology, Max Planck Institute for Chemical Ecology, Jena D-07745, Germany

16 Arid Land Agricultural Research Center, Unites States Department of Agriculture, Maricopa, Arizona 85138, USA

17 Division of Plant Sciences, University of Missouri, Columbia, Missouri 65211, USA

18 Institut fur Phytopathologie und Angewandte Zoologie, Justus-Liebig-Universitat Giessen, Giessen D35390, Germany

19 Department of Biology, University of Copenhagen, Copenhagen DK-1165, Denmark

20 King Abdulaziz University, 21589 Jeddah, Saudi Arabia

21 Centre for Social Evolution, Department of Biology, University of Copenhagen, Universiteitsparken 15, DK-2100 Copenhagen, Denmark

E-mail: jliebig@asu.edu 

Although eusociality evolved independently within several orders of insects, research into the molecular underpinnings of the transition toward social complexity has been confined primarily to Hymenoptera (for example, ants and bees). Here we sequence the genome and stage-specific transcriptomes of the dampwood termite Zootermopsis nevadensis (Blattodea) and compare them with similar data for eusocial Hymenoptera to better identify commonalities and differences in achieving this significant transition. We show an expansion of genes related to male fertility, with upregulated gene expression in male reproductive individuals reflecting the profound differences in mating biology relative to the Hymenoptera. For several chemoreceptor families, we show divergent numbers of genes, which may correspond to the more claustral lifestyle of these termites. We also show similarities in the number and expression of genes related to caste determination mechanisms. Finally, patterns of DNA methylation and alternative splicing support a hypothesized epigenetic regulation of caste differentiation.


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