1. Iyad Taleb Abu Awad and Dr. Abdul-Jalil Hamdan
Laboratory study on the predatory-prey relationship between the predatory bug, Orius laevigatus (Fiber) and the tobacco whitefly, Bemisia tabaci (Gennadius). 9th Arab Congress of Plant Protection, Nov., 2006, Damascus, Syria, Poster NE 30.
By:
Iyad Taleb Abu Awad and
Dr. Abdul-Jalil Hamdan

2. objectives:
To study the predator-prey relationships between the predatory bug O. laevigatus and the tobacco whitefly, B. tabaci as prey.
To study the effect of tomato and eggplant as host plants on the life history parameters of the predatory bug, O. laevigatus when offered the B. tabaci infestation as food.

3. List of Experiments: Four Experiments were conducted:
2004 : 1st Exp Preliminary Study On The Predator Prey Relationship Between The Predatory Bug, O. laevigatus And The Tobacco Whitefly, B. Tabaci
2005:
2nd Exp.: The effect of tomato and eggplant as host plants on the life history parameters of the adults O. laevigatus obtained from Bio Bee Company.
3rd Exp.: The effect of tomato and eggplant as host plants on the life history parameters of the nymphs of the predatory bug, O. laevigatus.
4th Exp.: The effect of tomato and eggplant as host plants on the life history parameters of the adults O. laevigatus obtained from the previous host plant leaf discs reared in Hebron University laboratory

4. Materials and methods:
2004:
1st Exp: Preliminary Study On The Predator Prey Relationship Between The Predatory Bug, O. laevigatus And The Tobacco Whitefly, B. tabaci
Materials and methods:
Sixty adults, one day old of O. laevigatus (32 females + 28 males) provided by BioBee Company were used in this experement.
Each bug was relased onto a tomato leaf disc heavily infested with B. tabaci and were kept for its adult longevity in a ventilated Petri dish cage 5cm diameter in an incubater under the standardized conditions of 25±1°C, 75±5% R.H. and 24L:0D.
Each dish was prepared with 2 cm diameter hole in the middle of the led, which was covered by 50 mesh cloth to provide ventilation.

5. Results
Table 1: Adult longevity of O. laevigatus fed on B. tabaci eggs and larvae under standard conditions of 25±1°C, 75 ±5% R.H. and continuous light (24L: 0D). Mean (days) ± S.E.
Sex
Replications
Adult Longevity
Males 28
19.07 ±±1.74
Females 32
±±2.36
P value
0.520 NS
Males + Females 60
18.03 ±±1.94
NS: Not significant at P value ≤ 0.05 (using t-test analysis).

6. Figure 1: Survival curve for O
Figure 1: Survival curve for O. laevigatus during its adult longevity when fed on B. tabaci infestation on tomato.

7. Table 2: Total number of whitefly stages consumed by adult O
Table 2: Total number of whitefly stages consumed by adult O. laevigatus offered heavy infestation of B. tabaci during its adult longevity. Mean ±S.E.
Sex of O. laevigatus
Rep.
Total B. tabaci Eggs Consumed/Adult Longevity
Total B. tabaci Larvae Consumed/Adult Longevity
P value
Total E+L Consumed/Adult Longevity.
Males 28
±± 68.9
±± 7.36
0.0001**
± 76.0
Females 32
±± 88.5
±± 8.67
± 97.0
0.719NS*
0.684NS*
0.715NS*
Males + Females 60
558.0 ±±56.7
54.83 ±±5.72
612.8 ±62.3
NS*: Not significant at P value ≤ 0.05 (using t-test analysis)
**: with significant differences at P value ≤ 0.05 (using t-test analysis).

8. NS*: Not significant at P value ≤ 0.05 (using t-test analysis).
Table 3: Average number of whitefly eggs and larvae consumed/day by adult O. laevigatus offered heavy infestation of B. tabaci under standard conditions of 25±1°C, 75 ±5% R.H. and continuous light (24L: 0.0D). Mean* ± S.E.
Sex
Rep.
Average Eggs Consumed/Day
Average Larvae Consumed/Day
P value
Average E+L Consumed/Day
Males 28
±±1.99
2.83 ±± 0.22
0.0001**
±± 2.19
Females 32
29.95 ±± 2.34
3.01 ±± 0.33
±± 2.64
0.899NS*
0.676NS*
Males + 60
29.77 ±±1.54
2.93± ± 0.20
32.70 ±±1.73
NS*: Not significant at P value ≤ 0.05 (using t-test analysis).
**: with significant differences at P value ≤ 0.05 (using t-test analysis).

9. Conclusions
Adults O. laevigatus found to be a promising natural enemy to B. tabaci as it was able to live for an adult longevity of days feeding on eggs and larvae of B. tabaci when offered on tomato leaf discs.
O. laevigatus adults were observed to be with significant preference for feeding on B. tabaci eggs more than on larvae.

10. 2005:
2nd Exp.: The effect of tomato and eggplant as host plants on the life history parameters of the adults O. laevigatus obtained from Bio Bee Company.
Materials & Methods:
Twenty replicates were reared on each host plant (tomato and eggplant)
Each replicate consisted of couple of newly emerged adults O. laevigatus and were offered heavy infestation of B. tabaci eggs and larvae on either tomato and eggplant leaf discs and reared in 5cm diameter Petri dish cages.
Each couple were transferred to freshly prepared cages every day and the previous leaf discs from each cages were kept in the incubator under the standardized conditions during incubation period of eggs and observed for hatching nymphs.

11. Results
Table 4: Adult longevity of O. laevigatus obtained from Bio Bee Company fed on B. tabaci infestation offered on either tomato or eggplant. Mean (days) ± S.E.
Host plant
Rep.
Adult longevity of males
Adult longevity of females
P value
Oviposition
period/ female
Postoviposition period/ female
Tomato 20
16.60±± 2.80
20.10 ±3.19
0.41NS
18.35 ±2.49
2.25 ± 0.72
Eggplant
13.95 ±1.76
16.50 ±2.32
0.39NS
15.35 ± 1.94
1.65± 0.54
0.43 NS
0.367NS
0.35NS
0.51NS
NS: Not significant at P value ≤ 0.05 (using t-test analysis).

12. Table 5: Total consumption of O
Table 5: Total consumption of O. laevigatus obtained from Bio Bee company during its adult longevity when fed on B. tabaci infestation offered on either tomato or eggplant. (Mean ± S.E.)
Host plant
Rep.
Egg consumption/
adult O.laevigatus
Larvae consumption/
P value
E +L consumption/
Tomato 20
706 ± 131
64.4 ±±10.7
0.001*
770 ± 141
Eggplant
453 ± 72.6
32.33 ±±3.78
485.3 ±±76.3
0.099NS
0.008*
0.084NS
NS: Not significant at P value ≤ 0.05 (using t-test analysis
*: with significant differences at P value ≤ 0.05 (using t-test analysis

13. Table 6: Daily consumption of adult O
Table 6: Daily consumption of adult O. laevigatus obtained from Bio Bee Company when fed on B. tabaci infestation offered on either tomato or eggplant. Mean ± S.E
Host plant
Rep.
Egg consumption/
adult O.laevigatus
Larvae consumption/
P value
E +L consumption/
Tomato 20
30.44 ±±1.84
3.20 ±±0.15
0.001*
33.65 ±±1.87
Eggplant
27.61 ± 0.65
2.45 ± 0.15
30.06 ± 0.56
0.154NS
0.074NS
*: with significant differences at P value ≤ 0.05 (using t-test analysis).
NS: Not significant at P value ≤ 0.05 (using t-test analysis).

14. Average nymph/ female/day
Table 7: Total number of nymphs hatched per O. laevigatus female obtained from Bio Bee Company when fed on B. tabaci infestation offered on either tomato or eggplant. Mean ±S.E.
Host plant
Pep.
Total nymph/ female
Average nymph/ female/day
Tomato 20
64.55 ±±8.83
3.67 ±±0.21
Eggplant
±±4.05
2.37 ±±0.15
P value
0.005*
0.001*
*: with significant differences at P value ≤ 0.05 (using t-test analysis).

15. 2005:
3rd Exp.: The effect of tomato and eggplant as host plants on the life history parameters of the nymphs of the predatory bug, O. laevigatus.
Materials & Methods:
Fifty newly hatched nymphs collected from cages where the previous experiment was reared on tomato cages were used for this experiment and each nymph was reared in 5cm diameter. Petri-dish on B .tabaci infestation offered on tomato leaf-discs.
And another fifty newly hatched nymphs collected from cages where the previous experiment was reared on eggplant cages were used for this experiment and each nymph was reared in 5cm diameter. Petri-dish on Bemisia infestation offered on eggplant leaf-discs.
Those nymphs were daily observed and transferred by a fine paint brush while observing them down a binocular dissecting microscope (40X) to freshly prepared cages.

16. Results O. laevigatus stages
Plate 1: First-instar nymph
Plate 2: Second- instar nymph

17. Plate 3: Third-instar nymph
Plate 4: Fourth-instar nymph

18. Plate 5: Fifth-instar nymph
Plate 6: Moulting shell of Fifth instar

19. Plate 7: adult of O. laevigatus

20. Table 8: Duration of development of O. laevigatus stages fed on B
Table 8: Duration of development of O. laevigatus stages fed on B. tabaci infestation offered on either tomato or eggplant. Mean (days)±S.E(n*)
Nymphal Instars
Host Plant
Tomato
Eggplant
P value
Eggs
4.26 ±±0.06(50)
4.30 ±0.07(50)
0.66NS N1
2.25 ±±0.06(48)
2.43 ±0.09(30)
0.11NS N2
2.10 ±±0.04(46)
2.07 ±0.05(27)
0.62NS N3
2.05 ±±0.03(38)
2.25 ±0.09(20)
0.08NS N4
2.60 ±±0.08(38)
2.22 ±0.10(18)
0.005** N5
3.46 ±±0.09(30)
4.70 ±0.15(10)
0.001**
Total nymphal development
12.43 ±±0.11(30)
13.20 ±0.24(10)
0.016**
Total development Egg-Adult
16.76 ±±0.14(30)
17.50 ±0.26(10)
0.032**
*: n = number of replications
**: with significant differences at P value ≤ 0.05 (using t-test analysis).
NS: Not significant at P value ≤ 0.05 (using t-test analysis).

21. % Mortality During Each Nymph % of females surviving to adult
Table 9: % Mortality of O. laevigatus during its nymphal stages when reared on tomato or eggplant leaf discs heavily infested with B. tabaci stages.
O. laevigatus Stage
(n* =50)
% Mortality During Each Nymph
% Survival To The Next Stage
(% Survival ± S.E**)
Tomato
Eggplant N1 4 40
96 ±±2.77
60 ±±6.92 N2 6
92 ±±3.83
54 ±±7.04 N3 16 14
76 ±±6.03
40 ±±6.92 N4
36 ±±6.78 N5
20 ±±5.65
Total mortality % 80
Total Number 20 30 10
% of females surviving to adult
50 ±±10.19
40 ±±7.07
n* = starting number
**: S.E for the % = 100 √ p q/n, p = proportion died, q = 1-p.

22. Figure 2: Survival curves of O. laevigatus females fed on B
Figure 2: Survival curves of O. laevigatus females fed on B. tabaci infestation on either tomato or eggplant leaf discs.

23. O.laevigatus nymphal instar
Table 10: Total consumption of O. laevigatus nymphs fed on B. tabaci infestation offered on different host plants.Mean ±S.E (n*).
O.laevigatus nymphal instar
Prey
Host Plant
B. tabaci stage
Tomato
Eggplant
P value N1
Eggs
40.08 ±±1.09(48)
40.10 ±±1.62(30)
0.99NS
Larvae
4.06 ±±0.44(48)
4.13 ±±0.26(30)
0.89NS
0.001**
E+L
44.15 ±±1.16(48)
44.23 ±±1.70(30)
0.97NS N2
±±0.81(46)
34.03 ±±0.75(27)
3.65 ±±0.19(46)
3.59 ±±0.17(27)
0.82NS
45.21 ±±0.78(46)
37.63 ±±0.72(27) N3
45.34 ±±0.80(38)
39.70 ±±0.88(20)
3.68 ±±0.23(38)
5.60 ±±0.49(20)
0.002**
49.02 ±±0.82(38)
±±1.15(20)
0.012** N4
77.28 ±±0.95(38)
41.83 ±±1.44(18)
8.28 ±±0.31(38)
4.72 ±±0.48(18)
±±1.03(38)
46.44 ±±1.79(18) N5
±±1.31(30)
99.80 ± ±2.01(10)
19.47±1.20(30)
9.90±0.60(10)
140.73±1.71(30)
109.70±2.43(10)
Total consumption/
all nymphs
Eggs
±±15.2(48)
±±15.1(30)
0.001**
Larvae
39.15 ±±2.16(48)
28 ±±1.82
P value
E+L
±±17.1(48)
±±16.8

24. 2005:
4th Exp.: The effect of tomato and eggplant as host plants on the life history parameters of the adults O. laevigatus obtained from the previous host plant leaf discs reared in Hebron University laboratory.
Materials & Methods:
Upon molting to adult, each O. laevigatus was observed for its sex, and each group of adults (males and females) that emerged at each certain day, were caged together for one day in 10cm diameter Petri dish and offered heavy infestation of B. tabaci on tomato or eggplant leaf discs.
On the second day, each male and female were separated and each was transferred to freshly prepared 5cm diameter Petri dish and offered heavy infestation of B. tabaci on tomato or eggplant leaf discs.
Each adult O. laevigatus was daily transferred to freshly prepared cages and the previous leaf discs for each female were also transferred to freshly prepared cages and kept for the incubation period in the incubator under the standardized conditions.

25. Adult longevity of males 22.33 ±±4.45(9) 14.00 ±±2.48(6) 0.13NS
Table 11: Adult longevity of O. laevigatus obtained from Hebron University lab and fed on B. tabaci infestation on Tomato or Eggplant. Mean (days) ± S.E. (n*)
Adult O. laevigatus
Host Plant
Tomato
Eggplant
P value
Adult longevity of males
22.33 ±±4.45(9)
14.00 ±±2.48(6)
0.13NS
Adult longevity of females
25.6 ±± 2.7(15)
15.00 ±±2.97(4)
0.029**
Pre-oviposition period
1.0 ±±0.0(15)
1.0 ±±0.0(40
1.0NS
Oviposition period
18.33 ±±1.24(15)
12.75 ±±1.93(4)
0.059NS
Post oviposition period
7.20 ±±1.98(15)
2.25 ±± 1.31(4)
0.055NS
*: n= number of replication
**: with significant differences at P value ≤ 0.05 (using t-test analysis).
NS: Not significant at P value ≤ 0.05 (using t-test analysis).

26. Table 12: Consumption of adult O
Table 12: Consumption of adult O. laevigatus obtained from Hebron University lab and fed on B. tabaci infestation. Mean ± S.E. (n)*.
O. laevigatus stage
Prey
Host Plant
Bemisia stage
Tomato
Eggplant
P value
Total consumption/
Adult male
Eggs
686 ±148(9)
374.7 ± ±80.1(6)
0.092NS
Larvae
58.8 ±±16.4(9)
27.17 ± ±5.51(6)
0.10NS
0.0030**
0.0075**
E+L
745 ±±164(9)
401.8 ± ±85.4(16)
Adult female
817.9 ± ±96.9(15)
± ±94.7(4)
0.016**
± ±7.63(15)
31.75 ± ±7.40(4)
0.010**
0.001**
0.0062**
883 ± ±104(15)
455 ± 102(4)
0.015**
Daily cons/
32.62 ± ±0.87(9)
25.14 ± ±0.44(6)
2.50 ± ±0.27(9)
1.87 ± ±0.11(6)
0.059
35.12 ± ±0.98(9)
27.02 ± ±0.45(6)
Daily consumption/
32.99 ± ±0. 59(15)
25.78 ± ±0.29(6)
2.67 ± ±0.06(15)
1.80 ± ±0.07(4)
35.67 ± ±0.60(15)
27.68 ± ±0.26(4)

27. Table 13: Total number of nymphs hatched per each O
Table 13: Total number of nymphs hatched per each O. laevigatus female obtained from colony reared in Hebron University lab. Mean ± S.E.
Host plant
Rep.
Total nymphs/female
Daily nymphs/female
Tomato 15
71.47 ± ±4.79
3.99 ± ±0.15
Eggplant 4
30.25 ± ±4.01
2.56 ± 0.19
P value
0.0001*
*: with significant differences at P value ≤ 0.05 (using t-test analysis).

28. Conclusions
O. laevigatus nymphs and adult were able to live and reproduce when feed on B. tabaci infestation offered on either tomato or eggplant.
O. laevigatus nymphs and adults preferred feeding on B. tabaci eggs more than on larvae when reared on tomato or eggplant.
The fertility of O. laevigatus was higher when reared on tomato than when reared on eggplant.
Nymphal mortality of O. laevigatus found to be highest on eggplant (80%) than that on tomato (40%).
The adult longevity of O. laevigatus reared on tomato found to be longer than that reared on eggplant.