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, 19-23 Nov., 2006, Damascus, Syria, Poster NE 30. By: Iyad Taleb Abu Awad and Dr. Abdul-Jalil Hamdan

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.

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

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.

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 17.13 ±±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).

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.

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 28 580.0 ±± 68.9 57.36 ±± 7.36 0.0001** 637.4 ± 76.0 Females 32 538.7 ±± 88.5 52.62 ±± 8.67 591.3 ± 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).

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 29.56 ±±1.99 2.83 ±± 0.22 0.0001** 32.39 ±± 2.19 Females 32 29.95 ±± 2.34 3.01 ±± 0.33 32.97 ±± 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).

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 18.03 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.

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.

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).

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

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).

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 34.85 ±±4.05 2.37 ±±0.15 P value 0.005* 0.001* *: with significant differences at P value ≤ 0.05 (using t-test analysis).

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.

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

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

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

Plate 7: adult of O. laevigatus

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).

% 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.

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.

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 41. 56 ±±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) 45. 30 ±±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) 85. 58 ±±1.03(38) 46.44 ±±1.79(18) N5 121.27 ±±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 325. 53 ±±15.2(48) 255.46 ±±15.1(30) 0.001** Larvae 39.15 ±±2.16(48) 28 ±±1.82 P value E+L 364.68 ±±17.1(48) 283.46 ±±16.8

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.

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).

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) 423. 5 ± ±94.7(4) 0.016** 65. 33 ± ±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)

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).

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.