4. Discussion
The results show that tomato plants expressing the
cry1Ab gene were protected against damage by H.
armigera in the same manner as that described by
Peferoen et al. (1990) for potato. The green house trials
showed that H. armigera did not damage the foliage or
the fruits of transgenic plants and no adverse effects
were observed on the growth ofthe plants. Infestation
by H. armigera on non-transgenic plants had an adverse
effect on their growth and the damage was so extensive
that they did not bear any fruit. Even under controlled
laboratory conditions, excised fruits from the Bt tomato
plants suffered very little damage by H. armigera larvae.
Surviving larvae grew very rapidly from 2nd instar to
5th instar on the non-transgenic fruits whilst on the
transgenic fruits, larval growth was very slow. Similar
results occurred on transgenic tomatoes infested with H.
armigera in Belgium (Jansens et al., 1992). Rarely does
H. armigera build up its own high population from the
initial low infestations on the tomato crop. Helicoverpa
armigera emigrating from other crops can infest
tomatoes in large numbers and most of the fruits suffer
extensive damage by the pest. By the time farmers detect
an infestation, it is usually very late and control
measures in the form of pesticide application are
ineffective. Control failure is probably because of the
lack ofpest monitoring system, improper timing of the
pesticide application, inappropriate insecticides and
resistance against the widely used pesticides (Matthews,
1993). Under such conditions, resistance imparted to
plants by Bt proteins, as described above, will be highly
desirable and will provide an effective and sustainable
control method for H. armigera in the field.
It is assumed that in a Bt tomato crop, eggs will be
laid by invading H. armigera moths and that newly
emerged larvae would invade the tomato tissue to feed
as there is no evidence that transgenic Bt plants inhibit
the oviposition or hatching oflepidopt erous pests
(Kumar, in press). Even though, emerging larvae would
suffer mortality on Bt plants, they would have caused
some damage to the terminal leaves and flowers ofthe
plants by initial penetration and probing ofthe tissue
prior to death. Therefore in order to manage H.
armigera on Bt tomato or Bt cotton, the following
tactics would be required to be considered in an
Results (
Thai) 1:
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4. DiscussionThe results show that tomato plants expressing thecry1Ab gene were protected against damage by H.armigera in the same manner as that described byPeferoen et al. (1990) for potato. The green house trialsshowed that H. armigera did not damage the foliage orthe fruits of transgenic plants and no adverse effectswere observed on the growth ofthe plants. Infestationby H. armigera on non-transgenic plants had an adverseeffect on their growth and the damage was so extensivethat they did not bear any fruit. Even under controlledlaboratory conditions, excised fruits from the Bt tomatoplants suffered very little damage by H. armigera larvae.Surviving larvae grew very rapidly from 2nd instar to5th instar on the non-transgenic fruits whilst on thetransgenic fruits, larval growth was very slow. Similarresults occurred on transgenic tomatoes infested with H.armigera in Belgium (Jansens et al., 1992). Rarely doesH. armigera build up its own high population from theinitial low infestations on the tomato crop. Helicoverpaarmigera emigrating from other crops can infesttomatoes in large numbers and most of the fruits sufferextensive damage by the pest. By the time farmers detectan infestation, it is usually very late and controlmeasures in the form of pesticide application areineffective. Control failure is probably because of thelack ofpest monitoring system, improper timing of thepesticide application, inappropriate insecticides andต้านทานต่อยาฆ่าแมลงที่ใช้กันอย่างแพร่หลาย (แมธธิวส์1993) ภายใต้เงื่อนไขดังกล่าว ต้านทาน impartedพืช โดยโปรตีนบีที ตามที่อธิบายไว้ข้างต้น จะสูงปรารถนาจะให้มีประสิทธิภาพ และยั่งยืนวิธีการควบคุมสำหรับ armigera H. ในฟิลด์จึงสันนิษฐานว่า ในการบีทีมะเขือเทศพืช ไข่จะวาง โดยบุกรุก H. armigera moths และที่ใหม่ตัวอ่อนที่ออกมาจะบุกเนื้อเยื่อของมะเขือเทศให้อาหารมีหลักฐานไม่ว่าถั่วเหลือง ยับยั้งพืชบีทีการฟักไข่หรือ oviposition oflepidopt erous ศัตรูพืช(Kumar ในข่าว) ถึงแม้ว่า ตัวอ่อนที่เกิดใหม่ จะประสบการตายบนพืชบีที อาจทำให้เกิดความเสียหายบางสถานีใบไม้และดอกไม้พืช โดยการเจาะเริ่มต้นและการตรวจสอบพื้นของเนื้อเยื่อก่อนที่จะตาย ดังนั้นเพื่อจัดการ H.armigera บนมะเขือเทศบีทีฝ้ายบีที ต่อไปนี้กลยุทธ์จะต้องพิจารณาในการ
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