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Bioassays in invertebrates
Electrophysiological methods
Classical electroantennography on insect antennae
general method responses not specific dose-dependent responses very useful for analytical
purposes
Connected gas chromatography – electroantennography (GC-EAG, GC-EAD)
insect antenna as selective detector
Bioassays in invertebrates
Olfactometer is used for testing volatile stimuli. In choice-test we observe responses to different stimuli (control, neutral, positive, negative). We observe movement of tested animal in the direction of tested compounds.
Klasické uspořádání testu antibakteriálních ůčinků (testovaná látka je nanesena na papír a přiložena na plotnu s bakteriální kulturou)
Y- olfactometr
Use of dummies of different shape
artificial leaves and other plant parts for studies of interactions of plants and insects
conspecific and heterospecific individuals for studies of social behaviour
artificial females for studies of sexual behaviour
Oviposition test on an artificial leave (polyurethane impregnated with plant leave extract)
Bioassays in invertebrates
Wind tunnelWind tunnel
Observation and evaluation of behaviour in response to volatiles, e.g. sexual behaviour (sexual pheromone): activation, oriented flight, finding of odour source, copulation attempts
Original equipment by Carde et al. :Tested compound is adsorbed on a filter paper (dispenser), placed on left, insect introduced on right.
Bioassays in invertebrates
Test of trail pheromones:
Traces 1 and 2 are “drawn” by tested compound and movements of ants on the drawing are followed
Bioassays in invertebrates
Biotesty u savcůVery complicated and demanding, problems with learning,
responses influenced by the researchers (primates), costly in humans
Bioassays in mammals
Design and evaluation of bioassaysDesign a planning of a bioassays is crucial
asking clear questions simple design, controlled environmental conditions sufficient number of experimental animals in the same
physiological state sufficient number of repetitions independent values! recording, documentation, digitalisation, later evaluation
negative and positive controls necessary avoid contamination elimination of animals in different physiological repetition, choice of suitable statistical method
In the literature we often find mistakes and misinterpretation.
BumblebeesBumblebees primitive social structureprimitive social structure one-year cycleone-year cycle fertilised queen overwintersfertilised queen overwinters starting colonies in springstarting colonies in spring workers take care of the broodworkers take care of the brood reproductive individuals emerge in reproductive individuals emerge in
summersummer mating in the open airmating in the open air old queen, workers, and males die in the old queen, workers, and males die in the
autumnautumn
Chemical signals in Chemical signals in bumblebees bumblebees
females' signals:females' signals: ·· sex pheromone sex pheromone of virgin queens of virgin queens (premating phase)(premating phase) · · queen's pheromonequeen's pheromone (queen is the only egg layer)(queen is the only egg layer)
males' signals:males' signals: ·· marking (sex) pheromones marking (sex) pheromones (premating behaviour)(premating behaviour)
workers' signals:workers' signals:· · dominant signalsdominant signals· · orientation in the nestorientation in the nest
male
queen
Bombus terrestrisBombus terrestris
Males‘ premating behaviourMales‘ premating behaviour
W aiting near the nest Perching species Patro lling species
SP E C IE S U S IN G PH E R O M O N E
SPE C IE S N O T U S IN G PH ER O M O N E
Male marking (sex) pheromones Male marking (sex) pheromones
producproduction in the tion in the cecephphalicalic part part of the labial glandof the labial gland
cephalic part consists of cephalic part consists of numerous acini and the ducts numerous acini and the ducts connecting particular acini connecting particular acini
multicomponent mixturesmulticomponent mixtures
Kullenberg et al. 1973; Ågren et al. 1979, Bergström et al. 1981
Usual Usual typtypes of compoundses of compounds alialiphphatic alatic alccoholoholss a andnd aldehyd aldehydeses ethylethyl esteresterss of fattyof fatty acidsacids terpenic alterpenic alccoholoholss a andnd theirtheir ester esterss (mono-, (mono-,
sessesququi-i-,, a andnd diterpen diterpeneses))
compositions are species - specificcompositions are species - specific compositions may be used as a toolcompositions may be used as a tool
for chemotaxonomyfor chemotaxonomy
OH
OAc
Bombus confususBombus confusus - Lo - Loccalitality of occurrencey of occurrence
Bombus confususBombus confusus
prematingpremating strateg strategyy - - perchingperching ( (elevated perchelevated perch))
mmororphphologicologicalal adaptaadaptationtion – – big eyesbig eyes
literaturliteraturee – – species oriented species oriented optically in search for mate optically in search for mate
male B. confusus on a perch
LLabiabial gland extractal gland extract
45 50 55 60 65 m in45 55 65 min45 55 65 min
Main components of the Main components of the secretionsecretion
OR
OCOCH3
1, R = H2, R = CO(CH2)4CH3
3, R = CO(CH2)6CH3
4, R = CO(CH2)8CH3
5
6OCOCH3
Double bond positionDouble bond position
m/z0
100
%
43
41
17361
55
8169
79
87171
12395122
231
174 232 404
m/z 173 m/z 231
(CH2)3
SS M+ 404
OAc(CH2)5
Z-Configuration of double bond (FT-IR)
3012 cm-1
Function of the labial gland Function of the labial gland secretionsecretion
Comparison of componentsComparison of components:: of the labial gland extractof the labial gland extract ofof h head-space ead-space sample of a marked perchsample of a marked perch of washing of a marked perchof washing of a marked perch ofof head-space head-space samplesample a andnd washing washing
of unmarked plants in the localityof unmarked plants in the locality
Labial gland extract
54
3222
1
Head-space of a marked perch (dry flower)
54
3
2
1
Head-space of and unmarked flower (blank)
2 0 3 0 4 0 5 0 6 0
Males’ marking behaviourMales’ marking behaviour 42 males marked individually42 males marked individually MarkingMarking – perches and – perches and
vegetation in the vicinity vegetation in the vicinity (straws) (straws)
Perches:Perches: dry flowers dry flowers Marking time:Marking time: morning, morning,
duration duration 18 min18 min
Number of marksNumber of marks of one male: of one male: 32-95 32-95
marking by B. confusus male
TerritoriTerritorieses of twoof two B. confusus B. confusus malesmales
ConclusionConclusion
B. confusus B. confusus is not a species oriented optically onlyis not a species oriented optically only Males produce a secretion in their labial glandMales produce a secretion in their labial gland SeSeccretretion is used for marking perches and surroundingsion is used for marking perches and surroundings B. confusus B. confusus is not exceptional among other perching speciesis not exceptional among other perching species
Methods used for the researchMethods used for the research: extra: extractionction, head-space, GC-MS, , head-space, GC-MS, derivatiderivatissaation withtion with DMDS, GC-FTIR DMDS, GC-FTIR, biological, biological observationsobservations..
Use of bioassays for localisation Use of bioassays for localisation of active components in mixturesof active components in mixtures
Identification of sex pheromone of horse chestnut leafminer (Cameraria ohridella) and its possible use for protection of chestnut trees
Cameraria ohridella Deschka et Dimić 1986 (Lepidoptera: Gracillariidae) originates from Macedonia; it is a dangerous pest feeding on horse chestnut, Aesculus hippocastanum (L).
First record in the Czech Republic: 1994 (South Moravia). Now it is spread in the whole country.
Biology (life cycle):4 generations / yearoverwintering in pupae first generation in March / April
Typical damage of leaves
Time of females’ calling activity
0
1
2
3
4
5
6
7
8
2 3 4 5 6 7 8 9 10 11 12
double bond position
EA
G r
esp
on
ses
(rel
)
EZ
A) Using EAG: Abdomens of calling females were dissected and extracted with hexane. EAG responses to saturated compounds (standards):
R-OH < R-Ac < 12:Ald < 14:Ald
Identification of sex pheromoneIdentification of sex pheromone
EAG map of 14:Ald monoenes:
B) Chemical approach:
Extract from 150 females didn’t give any good mass spectrum.
Strong EAG and GC-EAD signal on male antenna
Identification of sex pheromoneIdentification of sex pheromone
0
20
40
60
80
100
120
no reaction activation non-oriented flight oriented flight localization ofsource
3 FE
3 FE + PFBHA
Prove of aldehydic groupProve of aldehydic group
No response to standards of alcohols or acetates
PFBHA in MeOH was added to extract of females’ abdomens
EAG activity disappeared after derivatisation
Větrný tunel:
PFBHA
R-CH2-CH3
R-CH2-OCOCH3
R-CH2-OH
R-CH=O
+H2N
O
F
F
F
F
F
R-CH=NO
F
F
F
F
F
+
R-CH2-OH
R-CH2-OCOCH3
R-CH2-CH3
• 12:Ac, 14:Ald, and 14:OH have KI similar to the EAD-active peak
• (9E)-14:Ald (EAD-active) has a different KI from the pheromone
• KI of the EAD-active peak indicates two conjugated double bonds
C) Kováts index (KI):
Identification of sex pheromoneIdentification of sex pheromone
Conclusions from experiments A and B
• (9E)-14:Ald has a different KI and elicits lower EAG- and behavioural activity than the pheromone
• the pheromone may be tetradecadienal (TDDA) with double bonds located around C - 9
=> to prepare all isomers: 7,9-, 8,10- and 9,11-TDDA and test responses on GC-EAD
Identification of sex pheromoneIdentification of sex pheromone
D) GC-EAD of synthetic isomers:
8,10-TDDA
EAG of positional isomers TDDA:
9,11- < 7,9- << 8,10
GC-EAD recordings:
(E,Z)-8,10-TDDA elicits highest response of all isomers
KI and EAD responses to 8E,10Z-TDDA are identical with natural extract
Identification of sex pheromoneIdentification of sex pheromone
O
0
20
40
60
80
100
120
no reaction activation non-orientedflight
oriented flight localization ofsource
0,1 pg
1 pg
10 pg
100 pg
1000 pg
3 FE
Bioassays - Synthetic pheromone in the wind tunnel, dose response
(n = 25 males, 3-4 days old, day time 9-11 AM, air flow 0,4 m/s)
Field tests of the synthetic pheromone
0
100
200
300
400
500
6001st generation 2nd generation
Delta traps, checked daily
glue trap(420 males)
(n = 3)
Conclusions:• using combinatorial approach (EAG mapping and
Kováts retention index, (8E,10Z)-tetradeca-8,10-dienal was determined as sex pheromone of horse chestnut leafminer and synthesised in the laboratory
• chromatographic, EAG, and behavioural properties of synthetic and natural pheromone are identical
• synthetic substance is a specific attractant for malesin traps