Aggregation Pheromones – Pheromone which signals members of the same species to congregate together for a specific purpose like lady bugs do in your houseAlarm Pheromones – Pheromone which warns members of the same species to either attack or run from a given threat. Honey bees do this when the hive is attacked.Sex Pheromones – Pheromone which are sent to the opposite sex of a species to indicate their maturity and willingness to select a mate.
Ubiquitous means that it is seen throughout the entire species.
Sex pheromone traps have been used to capture crop pests. Spider pheromones may be used to attract specific spiders to recolonize crops after tilling fields. Pheromones may also serve as functional kairomones—deterring some crop pests from the area. For example Mexican bean beetles, Japanese beetles, and Potato Beetles are all known to preferentially avoid feeding on plants previously walked on by spiders.
Chemosensory hairs fire when they come into contact with certain chemicals which excite them. Do not react to pressure and structure of objects, unlike tactile hairs. Each chemosensory hair is triple innervatedTactile hairs respond to pressure and movement of objects as well as structure of objects such as silk.Not entirely known: could be integrated with each other.
Tarsal organs are thought to respond to volatiles in the air and or changes in humidity in the air. Recently found to have a chemosensory function.
“Mature” just means that during an assay a male showed a courtship response to the female silk
Justin Stover Spring Research Presentation (2)
Preliminary Identification of a Sex Pheromone in the Wolf Spider, Hogna helluoJustin StoverLou Ann TomLindsay DunkleMatthew Persons
What is a Pheromone? Chemical produced by individuals of a species that causes a behavioral response in other individuals of the same species ◦ Aggregation pheromones ◦ Alarm pheromones ◦ Sex pheromones
Previously Characterized Spider Pheromones Sex pheromones common among 42,000+ spider species but identified in only fourPhoto Eric Reynolds In contrast more than 1,600 insect Cupiennius salei pheromones have been identified ((S)-1,1-dimethyl citrate) (National Academy of Sciences) Photo: Stefan Sollfors Linyphia triangularis Agelenopsis aperta ((R)-3-hydroxybutyric acid & (8-methyl-2-nonanone)(R)-3-[(R)-3-hydroxybutyryloxy]-butyric acid) Argiope bruennichi (trimethyl methylcitrate)
Pheromones and Wolf Spider Agroecology High density in cropland year round (16 individuals/m2) Lies at the interface of detrital and terrestrial food webs Poorly understood behavioral mechanisms that allow them to remain at high densities within these disturbed habitats Large potential as biocontrol agents
Crop pests that reduce feeding or are repelled by chemical cues associated with the wolf spider Hogna helluo Mexican Bean Field Cricket Beetle Potato BeetleJapanese Beetle
Sex pheromones as biocontrol• Attract conspecifics and facilitate rapid colonization of recently plowed fields
Why Hogna helluo?: PracticalReasons• Large – likely produce more pheromones than smaller spiders• Resistant to desiccation required for some assays• Easy to breed and maintain in the lab for several generations
Spider Collecting • June-November 2011 • Snyder county cornfields adjacent to SU
Husbandry Methods◦ Separated by species, sex, and age◦ Each spider collected is assigned an individual ID◦ Housing 16oz. White Deli dishes (Hogna helluo) Dampened peat moss◦ Feeding Cricket nymphs once weekly
Possible Types and Sources of Pheromones• Volatiles from Cuticle• Non-volatiles from Cuticle• Volatiles from Silk• Non-volatiles from Silk
How Spiders Detect Chemical Cues Chemosensory Hair
Tarsal Organs: Receptors for Volatile Pheromones
Volatiles from Cuticle/Silk (CLSA)• Closed loop stripping apparatus• Mature female H. helluo used and compared to adult males• Pumps ran for 4 consecutive 12 hour trails on one activated carbon filter• Controls ran for 12 hours• Following trial filters were washed with dichloromethane, centrifuged and then were analyzed by Gas Chromatography- Mass Spectrometry
Gas Chromatogram of Three Filter Types female spider 1500000 male spider control 1000000 Abundance 500000 0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Time (min)
Gas Chromatograms Enlarged 1500000 1500000Abundance Abundance 1000000 1000000 500000 500000 0 0 2 3 4 5 6 7 8 8 9 10 11 12 Time (min) 1500000 Time (min) Abundance 1000000 Female Spider Male Spider 500000 Control 0 13 14 15 16 17 18 Time (min)
Table of Sex-Specific Compounds from GC Compound Male Female
Table of Sex-Specific Compounds from GC Compound Male Female Octane, 2,5,6-trimethyl No Yes Eicosane, 3-methyl No Yes 2,2,7,7- No Yes tetramethyltricyclo[184.108.40.206(1,6)]undec-4-en-3- one Dodecane, 4-methyl No Yes
Table of Sex-Specific Compounds from GC Compound Male Female Octane, 2,5,6-trimethyl No Yes Eicosane, 3-methyl No Yes 2,2,7,7- No Yes tetramethyltricyclo[220.127.116.11(1,6)]undec-4-en-3- one Dodecane, 4-methyl No Yes Ethylbenzene Yes No Decane, 2,3,4-trimethyl Yes No Hexane, 2,2,3-trimethyl Yes No 1-hexanol, 2-ethyl Yes No
Table of Sex-Specific Compounds from GC Compound Male Female Octane, 2,5,6-trimethyl No Yes Eicosane, 3-methyl No Yes 2,2,7,7- No Yes tetramethyltricyclo[18.104.22.168(1,6)]undec-4-en-3- one Dodecane, 4-methyl No Yes Ethylbenzene Yes No Decane, 2,3,4-trimethyl Yes No Hexane, 2,2,3-trimethyl Yes No 1-hexanol, 2-ethyl Yes No 2,2,6,6-Tetramethylheptane Yes Yes Octane, 2,3,6,7-tetramethyl Yes Yes 1-hexanol, 2-ethyl-2-propyl Yes Yes 2,5-cyclohexadiene-1,4-dione, 2,6-bis(1,1- Yes Yes dimethyl)
Volatiles from Silk• Unmated adult females were compared to, adult males, and empty controls• Spiders were placed in glass vials and labeled• Trials ran overnight for 12 hours each• Each vial was serially rinsed with the same initial 1 mL of dichloromethane and then capped. The dichloromethane from the aggregate wash of 15 vials was then filtered and analyzed by GC/MS.
Gas Chromatograms of Silk with Two Primary Compounds found and Configuration 80000 silk 60000Abundance 3-Penten-2-ol (12.4%) 40000 20000 0 2.5 3.0 3.5 4.0 Time (min) 5-Methyl-1-hepten-4-ol (12.7%)
Other Explanations for Differences Diet-based differences Individual Odor Signatures Differences in metabolic processing between the sexes
Future Directions Compare to juveniles and mated females Confirmation Synthesis Behavioral Assays singly and in combination Field Test Other species
ArachnowledgementsWe would like to thank Lindsay Dunkle and Lou Ann Tom forpreparing and running the GC-MS and for analyzing the data. Wewould also like to thank Thomas Duff, Rizwan Khan, Kody Hummeland Cierra Omlor for helping to capture and maintain the spiders forthis study.