A brief statement on the studies of the ecological impact of Bt cotton

conducted by Dr. Kongming Wu's lab, Institute of Plant Protection, CAAS

 

Dr. Kongming Wu is an entomologist who has been engaged in the study of

cotton insect pests since 1985 and the ecological impact of Bt cotton

since 1996. He is a professor and director of the Department of

Agricultural Entomology, Institute of Plant Protection, Chinese Academy of

Agricultural Sciences (CAAS), Beijing, China; a member of the National GMO

Biosafety Committee; and Chief Scientist of the National High-Tech Program

on the ecological safety of Bt cotton in China. His laboratory is one of

four mentioned by the Greenpeace-published Report on the environmental

impact of Bt cotton in China.

 

The following is Kongming Wu's brief statement.

 

When the report gA Summary of Research on the Environmental Impact of Bt

Cotton in Chinah written by Prof. Dayuan Xue, Nanjing Institute of

Environmental Sciences, was published by Greenpeace in early June 2002, I

was in USA as a visiting scholar. Some friends sent me the report by

e-mail, I just read the abstract because my computer was failed to open

the PDF attachment.

 

After carefully reading the report when I was back to Beijing on June 21,

I amazedly found that our studies on ecological impacts of Bt cotton were

summarized incorrectly by the author. In fact, our results strongly oppose

the major conclusions in Green Peacefs report and do not support their

views. On behalf of my laboratory, I would like to make a statement for

clarification our research results.

 

Supported by the National High-Tech Program, the Basic Research Program

and the State Key Project of the Ministry of Science and Technology of

China, and a Special Project for Development of Cotton Production from the

Ministry of Agriculture, China, a series of ecological safety studies of

Bt cotton have been conducted by the Cotton Insect Research Group,

Institute of Plant Protection, Chinese Academy of Agricultural Sciences

since 1995, which include efficacy of Bt cotton against Helicoverpa

armigera (CBW), field abundances of natural enemies, impacts on non-target

insect pests, arthropod community structure in the Bt cotton ecosystem,

baseline for CBW resistance to Cry1Ac protein, resistance monitoring,

selection of resistant strains of CBW and resistance inheritance,

resistance mechanisms, evaluation of natural refugia function, and the

biology of CBW in relation to resistance evolution. The major results

related to the report are listed as follows.

 

1. Several Bt cotton varieties, developed by the Biotechnology Research

Institute, CAAS and Monsanto Co. were evaluated for resistance to

Helicoverpa armigera during 1997-2001. The results showed that Bt cotton

possessed high levels of field-efficacy against H. armigera, with about

80-95% control in different years. In a general year of CBW occurring,

damage from CBW on cotton was controlled effectively.

 

2. Influences of Bt cotton planting on the population dynamics of cotton

aphid, Aphis gossypii Glover, another key insect pest of cotton in China,

were investigated during 1998-2001. The results showed that population

densities of cotton aphids were significantly higher in plots of

conventional cotton with both pyrethroid and organophosphate insecticide

applications than in Bt cotton fields because of the resistance of cotton

aphids to the majority of insecticides used for control of H. armigera and

lower densities of predators in late June and early July caused by

insecticide use. ,  This suggests that Bt cotton planting not only played

an important role in the control of H. armigera, but also efficiently

prevented cotton aphid resurgence that would have occurred with

insecticide applications for control of H. armigera.

 

3. Lygus lucorum Meyer-Dür, Adelphocoris fasciaticollis Reuter and

Adelphocoris lineolatus (Goeze) (Hemiptera: Miridae) are important

secondary insect pests in cotton fields in northern China. The seasonal

dynamics of their mixed populations on a transgenic variety expressing the

insecticidal Bt protein Cry1Ac and a cotton line expressing the proteins

Cry1Ac and CpTI (cowpea trypsin inhibitor gene) were compared with

non-transgenic varieties from 1998 to 2001. The results indicated that

there were no significant differences between the population densities of

these bugs on unsprayed normal cotton and unsprayed transgenic cotton.

However, mirid densities on sprayed transgenic cotton were significantly

higher than those on sprayed conventional cotton because of the greater

number of insecticide applications against Helicoverpa armigera on the

conventional cotton.

 

4. Field abundances of insect predators on Bt cotton were evaluated in

1997-2001 at two sites in northern China. The results indicated that, in

comparison with the normal cotton plots where insecticides were regularly

used against cotton bollworm, the population densities of predators in Bt

cotton plots were significantly higher.

 

5. Arthropod community structure in the Bt cotton ecosystem was

investigated in 2000-2001.  Three treatments, including Bt cotton (no

sprays), normal cotton (no sprays), and normal cotton (regular spraying),

were included. Arthropods were collected using a portable suction device.

The results indicated that the diversity of arthropod communities in Bt

cotton plots was higher than that in the other treatments.

 

6. Geographical variations in sensitivity of cotton bollworm to the Bt

protein Cry1A(c) was studied in 1997 to establish a geographical baseline

for comparing future population responses to increased use of Bt products

in agriculture in China. More than 20 bollworm populations were collected

from 5 cotton-growing regions of China, and the dose responses to Cry1A(c)

protein in terms of mortality and growth inhibition were evaluated. On the

basis of the baseline study, sensitivities of field populations of

Helicoverpa armigera to Cry1A(c) were monitored during 1998 ? 2001. A

total of 55 strains were sampled, and most of them were collected from Bt

cotton planting regions. It was determined that the field populations

sampled during the 4 year's study were susceptible to Cry1A(c) protein,

and no development of resistance was apparent.

 

7. Function of natural refuge was evaluated during 1999-2001. Although

growth and development of H. armigera on Bt cotton was much slower than on

common cotton, there was still a high probability of mating between

populations from Bt cotton and other sources due to the scattered

emergence pattern of H. armigera adults, and overlap of the 2nd and 3rd

generations. In a cotton and corn growing region, early and late planted

corn provided a suitable refuge for the 3rd and 4th generations of H.

armigera, but not for the 2nd generation. In a cotton and soybean/peanut

mixed system, non-cotton crops provided a natural refuge for the 2nd to

4th generation H. armigera, but the function of the refuge was closely

depended on the proportion of Bt cotton.

 

General Conclusions

Cotton bollworm is one of the most important agricultural pests in China.

Both synthetic pyrethroids and organophosphate insecticides have been used

over the past 20 years to control it. Since the late-1980s, applications

of chemical insecticides have caused a series of serious issues, such as

the insect resistance and resurgence, decrease of farmer's income,

pesticide residue and environment pollution.

 

By several year studies, we conclude that Bt cotton possesses a high

efficiency for control of H. armigera, and its planting in China has the

advantages of reducing the use of chemical insecticides for control of two

key insect pests, cotton bollworm and cotton aphid, which would benefit

for decreasing environmental pollution and related costs from the insect

control in cotton, prolong the useful time of pyrethroid and

organophosphate insecticides by reducing the area sprayed and frequency of

sprays, and increase the potential for natural and biological control of

cotton insect pests.

 

For further reading please refer to the following papers:

 

1. Wu, K., G. Liang & Y. Guo. 1997. Phoxim resistance of cotton bollworm

in China. J. Econ. Entomol. 90(4): 868-872.

2. Wu, K., Y. Guo & N. Lv 1999. Geographic variation in susceptibility of

Helicoverpa armigera (Lepidoptera: Noctuidae) to Bt insecticidal protein

in China. J. Econ. Entomol. 92(2): 273-278.

3. Wu, K., Y. Guo, and W. Wang. 2000. Field resistance evaluations of Bt

transgenic cotton GK series to cotton bollworm. Acta Phytophylacica

Sinica. Vol. 27(4): 317-321.

4. Liang, G., W. Tan, and Y. Guo. 2000. Study on screening and inheritance

mode of resistance to Bt transgenic cotton in cotton bollworm. Acta

Entomologica Sinica. 43(sup.): 57-62.

5. Liang, G., W. Tan, and Y. Guo. 2000. Studies on the resistance

screening and cross-resistance of cotton bollworm to Bacillus

thuringiensis. Scientia Agricultura Sinica. 33(4): 46-53

6. Wu, K. 2001. IPM in Bt cotton. In: Jia, S. et al. (Ed), Transgenic

cotton. Sciences Press, Beijing, pp. 218-224.

7. Zhang, R. K. Wu and Y. Guo. 2001. On the spatio-temporal expression of

the contents of Bt insecticidal protein and the resistance of Bt

transgenic cotton to cotton bollworm. Acta Phytophylacica Sinica. Vol.

28(1): 1-6.

8. Wu, K., G. Xu and Y. Guo 2001 Seasonal population dynamics of tobacco

white fly adults on cotton in northern China. Plant Protection. 27(2):

14-15.

9. Liang, G., W. Tan, and Y. Guo. 2001. Comparison of some detoxification

enzyme and midgut protease activities between resistant and susceptible

cotton bollworm population to Bt. Acta Phytophylacica Sinica. Vol. 28(2):

133-138.

10. Zhang Yongjun, Xu Guang, Guo Yuyuan, Wu Kongming. 2001. Analysis of

volatile components in transgenic Bt cotton and their parental varieties.

Acta Ecologica Sinica. 21(12): 2051-2056.

11. Liang, G., W. Tan, and Y. Guo. 2001. Pathological changes in midgut

tissues of cotton bollworm larvae after intaking transgenic Bt cotton.

Cotton Science. 13(3): 138-141.

12. Zhang Y., J. Yang, Y. Guo and K. Wu 2002. Study on the interactions

between exogenous Bt-ICP and cotton terpenoids chemicals. Scientia

Agricultura Sinica. 35(5): 514-519.

13. Zhang Y., J. Yang, Y. Guo, K. Wu and W. Wang. 2002. Changes of Bt-ICP

and main secondary resistant metabolites in Bt transgenic cotton after

being induced by chemical regulators. Cotton Sciences. 14(3): 131-133.

14. Wu K., Y. Guo, N. Lv, J. Greenplate and R. Deaton 2002. Resistance

monitoring of Helicoverpa armigera (Lepidoptera: Noctuidae) to Bt

insecticidal protein in China. J. Econ. Entomol. 95 (3).

15. Wu K., Y. Guo and S. Gao 2002. Evaluation of the natural refuge

function for Helicoverpa armigera (Hübner) within Bt transgenic cotton

growing areas in north China. J. Econ. Entomol. 95 (4).

16. Wu K., W. Li, H. Feng and Y. Guo 2002. Seasonal abundance of the

mirids, Lygus lucorum and Adelphocoris spp. (Hemiptera: Miridae) on Bt

cotton in northern China. Crop Protection (in press).

17. Huang M., P. Wan, K. Wu, J. Wu, X. Fan and M. LI. 2002. Resistance

evaluation of Bt transgenic cotton to cotton bollworm, Helicoverpa

armigera, in mid-Changjiang River Valley. Acta Gossypii Sinica (in press).

18. Wu K. and Y. Guo. Influences of Bt cotton planting on population

dynamics of cotton aphid, Aphis gossypii Glover, in northern China.

Environ. Entomol.( accepted)

19. Li W., G. Ye, K. Wu, X. Wang and Y. Guo. Evaluation of the impact of

Bt/CpTI transgenic cotton and corn on the growth and development of

mulberry silkworm, Bombyx mori Linnaeus (Lepidoptera: Bombyxidae).

Scientia Agricultura Sinica. ( accepted).

 

Dear all,

 

My laboratory is one of four mentioned by the Greenpeace-published Report

on the environmental impact of Bt cotton in China. Attached is my formal

response to the report (Above). Please transfer to anyone who is

interesting in the event.

 

Best regards,

 

Dr. Kongming Wu

Professor and Director of Department of

Agricultural Entomology,

Deputy Director of State Key Laboratory for

Biology of Plant Diseases and Insect Pests

Institute of Plant Protection

Chinese Academy of Agricultural Sciences

Beijing, 100094, P. R. China

Email: wkm@caascose.net.cn

 

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