Presentation on theme: "Testing of the Egg Parasitoids Trichogramma bourarachae Pintureau and Trichogramma nerudai Pintureau against some Lepidopterous insect pests in Sudan Sara."— Presentation transcript:
Testing of the Egg Parasitoids Trichogramma bourarachae Pintureau and Trichogramma nerudai Pintureau against some Lepidopterous insect pests in Sudan Sara A. A. Kehail and Hayder Abdelgader Agricultural Research Corporation, Crop Protection Research Centre, P. O. Box 126 Wad Medani, Sudan Introduction Trichogramma (Hymenoptera: Trichogrammatidae) are extremely tiny wasps, the female Trichogramma lay their eggs within a host eggs. Each female parasitizes from 10 to 190 eggs during its life. More than one parasite egg may be inserted into each host egg and this is based, on the egg size. After hatching, the parasitoid larvae feed on the contents of the host egg. The wasps pupate within the egg and adults chew an emergence hole to escape. There are several species and strains of Trichogramma, which vary considerably in their ability to control different insects and in their adaptation to different environmental conditions and crops. Trichogramma have been used as inundative biological control agents against a range of agricultural pests, mainly lepidopterans. Objective The current study was carried to test the acceptance of two Trichogramma species (Trichogramma bourarachae Pintureau; and Trichogramma nerudai Pintureau) against host eggs of different Lepidopterous insect pests in Sudan. Trichogramma Wasp A female Trichogramma wasp while laying her eggs inside a host egg A Trichogramma wasp while emerging out of the parasitized egg Materials and Methods Laboratory work was conducted at the Agricultural Research Corporation (ARC), Wad Medani, Sudan during 2008-09. Trichogramma bouraracha, T. nerudai and Sitotroga cereallela were brought from AMW-N ü tzlinge Company (Germany), to Sudan in 2008 and 2009. Eight species of lepidopterous insect pests were selected either from storage such as, Sitotroga cerealella, Ephestia calidella and Corcyra cephalonica or from their host plants such as Helicoverpa armigera, Earias insulana, Trichoplusia ni, Spodoptera exigua and Sesamia cretica. These hosts were collected at different stages from the ARC research fields and reared in the laboratory under room temperature until the adults emerged and laying eggs. The papers containing eggs were cut to pieces (egg-cards) before offered to different numbers of T. bouraracha and T. nerudai separately in glass tubes (15 cm long × 3 cm Ø ). A small drop of honey was added to each egg-card to provide a food for Trichogramma wasps. The parasitized eggs as well as the hatching adults were counted using a binocular microscope. The experiment was replicated three times (as average), the unhatch eggs were excluded, average parasitism, emergence rate and female % for tested Trichogramma / host was determined. Grain moth, Sitotroga cerealella Oliver Bollworm, Helicoverpa armigera Hub. Spiny bollworm, Earias insulana Boisd Cabbage looper, Trichoplusia ni Hub. Leafworm, Spodoptera exigua Hub Stem borer, Sesamia cretica Led. Results All the tested eggs of the pest insects were accepted by the host females of Trichogramma nerudai and T. bourarachae as showed in the results (Table and fig. 1). The highest average of emergence rates of both Trichogramma species were 2.68 and 2.02 respectively appeared from Sesamia cretica, while the storage pests (Ephestia calidella and Sitotroga cerealella) showed the lowest appearing for the both Trichogramma species (1.00 - 1.08) in compared to other tested host. The highest female percent was emerged from Corcyra cephalonica (T. nerudai and T. bourarachae, 82 % and 70 % respectively) and the lowest percent was emerged from E. calidella for both Trichogramma species (38 % and 21 % respectively). Helicoverpa armigera and Earias insulana showed similar female percent for both T. nerudai and T. bourarachae (Table and fig. 2). Figure 1: the emergence rate of T. nerudai and T. bourarachae from different host eggs Figure 2: the % female of T. nerudai and T. bourarachae emerging from different host eggs Parameter (Mean ± SD) Trichogramma sp. Hosts Sitotroga cerealella Ephestia calidella Corcyra cephalonica Helicoverpa armigera Earias insulana Trichoplosia ni Spodoptera exigua Sesamia cretica Number of parasitized eggs T. nerudai 43.0 ± 33.98 10.67 ± 3.7930.83 ± 21.3934.25 ± 12.6125.57 ± 8.689.5 ± 2.8916.5 ± 10.8520.0 ± 14.55 T. bourarachae 30.67 ± 14.19 15.75 ± 7.3739.6 ± 14.1532.4 ± 15.2718.83 ± 7.819.75 ± 7.546.33 ± 3.7922.33± 14.94 Number of Emerged adults T. nerudai 47.25± 38.42 11.33 ± 3.5141.83±24.7362.75± 1.0351.0±16.1116.75± 8.8533.0 ± 28.9353.0 ± 37.94 T. bourarachae 32.67± 14.57 15.75 ± 7.37 49.6 ± 19.3159.8± 31.5030.83±21.0616 ± 17.369 ± 5.0045 ± 35.44 Emergence rate T. nerudai 1.07 ± 0.13 1.45 ± 0.261.96 ± 0.492.04 ± 0.491.77 ± 0.891.79 ± 0.592.68 ± 0.54 T. bourarachae 1.08 ± 0.08 1.00 ± 0.00 1.25 ± 0.151.82 ± 0.211.57 ± 0.721.42 ± 0.401.58 ± 0.522.02 ± 0.42 % FemaleT. nerudai 77 ± 0.05 38 ± 0.38 82 ± 0.0964 ± 0.1365 ± 0.1173 ± 0.0978 ± 0.1473 ± 0.11 T. bourarachae 69 ± 0.02 21 ± 0.43 70 ± 0.1666 ± 0.1364± 0.0960 ± 0.1568 ± 0.2167 ± 0.08 Date moth, Ephestia calidella Guen Rice moth, Corcyra cephalonica St. Table: the emergence rate and the female percentage of different host eggs parasitized by Trichogramma nerudai and T. bouraracha. SD = Standard deviation Conclusion and Recommendation All the tested hosts showed the highest emergence rate compared with the storage pest, this difference in the emergence rate might be due to their egg size. More than 50 % females were emerged from all the tested host eggs except Ephestia calidella for both Trichogramma sp.. T. nerudai was found to be more fecund and fertile relative to T. bourarachae (high % female). So we recommend to involve the egg parasitoids Trichogramma within the strategy of IPM Program in Sudan.