Q and B biotypesQ and B biotypes–– distribution, distribution, cropcrop--relation, and their relevance relation, and their relevance
to insecticide resistanceto insecticide resistance
BB QQ
Rami Horowitz, Rami Horowitz, Svetlana Kontsedalov, Svetlana Kontsedalov, Vadim Khasdan Haggai Breslauer Vadim Khasdan Haggai Breslauer
and Isaac Ishaayaand Isaac IshaayaARO, Dept. of Entomology,
Gilat Research CenterThe Volcani Center, Bet Dagan, Israel
biotype B biotype Q
Two biotypes of B. tabaci have been identified in Israel:
B B -- (early 1990(early 1990’’s)s)Q Q -- (2000) (2000)
RAPD-PCR products of various Bemisia tabaci strains from Israel
1 2 3 4 5 6 7
Lane 1Lane 1-- DNA ladder; 5DNA ladder; 5-- a sample without DNAa sample without DNA
Lanes 2, 4, 7Lanes 2, 4, 7-- samples from samples from SdeSde--EliyahuEliyahu, w, w--Negev & standard BNegev & standard B
Lanes 3, 6 Lanes 3, 6 –– samples from the Carmel Coast & standard Qsamples from the Carmel Coast & standard Q
Biotypes ofBiotypes of B. tabaci B. tabaci in Israel, 2002in Israel, 2002--55
B
Q,b
Q,bQb
B
B
Q
B
Bqq
Q,B
Crossing studies, Q/B (field strains)Crossing studies, Q/B (field strains)Offspring Parents
Sex ratioFemale: Male
Males FemalesMales 40
Females 20
1.0 :0.7206360Negev (B)Negev (B)
0.0:1.02450Arava (Q) Negev (B)
1.0:0.7316458Arava (Q)Arava (Q)
0.01:1.05036?Negev (B)Arava (Q)
In the Arava Valley (Israel); biotype In the Arava Valley (Israel); biotype survey was conducted during 2004survey was conducted during 2004––5 5
Organic vs. conventional crops
• In the Arava Valley (Israel); biotype survey was conducted during 2004 – 2005.
• Greenhouse organic peppers, cucumbers and melons – B.B.
• Conventional greenhouses – Mostly QQ
Proportion of B. tabaci biotype Q and B sampled from sunflower and cotton fields during 2005
cotton season in the Ayalon Valley, Israel
May-3 May-31 June-19 Yuly-18 Aug-24Date
40
60
80
100
120
Perc
ent
Q
Sunflower Cotton
Endosulfan 'Polo' Cypermethrin
Av-05
May-31 June-21 July-18 Aug-24Date
0
20
40
60
80
100
120
Perc
ent Q
Sunflower cotton
Endosulfan 'Polo'Endosulfan
HC-05
Proportion of B. tabaci biotype Q and B sampled from sunflower and cotton fields during 2005
cotton season in the Carmel Coast, Israel
Biotype tolerance to insecticides Biotype tolerance to insecticides affects their field compositionaffects their field composition
AA BBB B QQ
Various populations of Various populations of Bemisia tabaciBemisia tabaci collected in Israel, collected in Israel, their biotype definition and resistance to pyriproxyfentheir biotype definition and resistance to pyriproxyfen
Resistance (RR)
BiotypeLocation Collection date
Strain
1BTzor’a1987S *2BW- Negev1999Yesha-99 4BBet Dagan2000BD-00
0.4BW- Negev2000Negev-009BBet She’an2000BS-00
1,200QGH, W- Negev1991Pyri-R*637QCarmel Coast 2000HC-00167Q>bAyalon Valley1999AV-99 81Q>bAyalon Valley2000AV-0025Q>bW- Galilee2000W-Gal
B
Early Early seasonseason Late seasonLate season
0.0001 0.001 0.01 0.1 1 10 100 10001
510
30
50
70
9095
99
S
2002LS
2003ES
2003LS
HC-03-tigConcentration (ppm)
Egg
mor
talit
y (%
)Monitoring pyriproxyfen resistance, Monitoring pyriproxyfen resistance,
Carmel Coast 2002Carmel Coast 2002--33
Resistance to Pyriproxyfen Resistance to Pyriproxyfen and biotype Qand biotype Q
In areas where the use of pyriproxyfen ceased, resistance levels declined to some extent,while…Level of susceptibility was restored completely in the lab (gen. 15-20).
Biotype-related resistance?
Monitoring Pyriproxyfen Monitoring Pyriproxyfen Resistance, Ayalon Valley, IsraelResistance, Ayalon Valley, Israel
0.001 0.01 0.1 1 10 100 1000
Concentration, ppm
1
510
30
50
70
9095
99
Egg
mor
talit
y, %
S
1996
2001
2002
2003
2004
2005
S
Lab assaysLab assays
0.0001 0.001 0.01 0.1 1 10 100 10001
510
30
50
70
9095
99S
Unt
Act
Msp
G0
Tiger-Sel-02-15g
Egg
mor
talit
y (%
)
Concentration (ppm)
Susceptibility of Susceptibility of B. tabaciB. tabaci strain (AVstrain (AV--02) to pyriproxyfen02) to pyriproxyfen
Laboratory conditions (15Laboratory conditions (15thth generations)generations)
BBBB
Q>B
UntUnt=untreated=untreated;; G0 =the original G0 =the original strainstrain;;;;SS=susceptible =susceptible ;;(thiamethoxam)(thiamethoxam) Act=selection to ActaraAct=selection to Actara
MspMsp=selection to Mospilan (acetamiprid)=selection to Mospilan (acetamiprid)
0.001 0.01 0.1 1 10 100
Concentration, ppm
1
510
30
50
70
9095
99
Egg
Mor
talit
y, %
S- Strain
1st Gen.
Untr.
Pyri-Sel.
mix-G20
Mix of Q&B (1:1, with similar R) maintained for 20 generations; partly pressurized with
pyriproxyfen; another part - kept untreated
B
BQ
B
B&Q
Proportion of B. tabaci biotypes throughout the generations
PyriPyri--selectionselection
untreateduntreatedGeneration Generation
1B:1Q1B:1QG-0
1B:1QBG-4
Q>BBG-8
QBG-12
QBG-16
QBG-20
Interaction ofInteraction of B. tabaciB. tabaci BiotypeBiotype
1. Both the B and Q biotypes are present in Israel2. Field populations may consist of a mixture of
biotypes3. Reproductive incompatibility maintains their
genetic isolation4. A possible link exists between B. tabaci
biotypes and insecticide resistance5. Tolerance of Q-type to pyriproxyfen,
neonicotinoids and other new insecticides (?)6. Without exposure to insecticides – higher
fitness to “B” (?)7. Insecticide applications select for Q-type.
We can surmise the following scenarioAppearance of Q biotype accompanies resistance to pyriproxyfen and/or neonicotinoids.
Treatments in accordance with IRM programs moderate selection for resistance to those insecticides and concurrently reduce the appearance of the Q-type.
Reuse of the above insecticides against B. tabacimay increase occurrence of the Q-type and development of resistance to one or another group of insecticides.
(Selection to insecticides in B biotype of B. tabaciis feasible, but it is probably slower than in the Q type).
Unsolved questions
1. Does B-type have higher fitness than Q-type (is it more competitive)?
2. Why does “B” take over “Q” after several generations under lab conditions?
3. Reproductive barrier: attraction, mating behavior, fertility, symbiont related?
QQBB
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