2 results
Effects of azadirachtin-based insecticides on the egg parasitoid Trichogramma minutum (Hymenoptera: Trichogrammatidae)
- D.B. Lyons, B.V. Helson, R.S. Bourchier, G.C. Jones, J.W. McFarlane
-
- Journal:
- The Canadian Entomologist / Volume 135 / Issue 5 / October 2003
- Published online by Cambridge University Press:
- 02 April 2012, pp. 685-695
-
- Article
- Export citation
-
Effects of neem formulations on the reproduction and survival of the egg parasitoid Trichogramma minutum Riley were examined to assess the compatibility of the two control strategies in integrated pest management programs. A laboratory bioassay was developed for this purpose, which could be used as a model ecotoxicological system. Eggs of the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), which had been treated with an acetone solution containing an azadirachtin-based formulation, were presented to individual T. minutum females. These eggs were held until parasitoids completed development and emerged from the eggs. Survival of T. minutum females 1 day after treatment, number of Mediterranean flour moth eggs parasitized, proportion of parasitized eggs from which adults emerged, and sex ratios of emerging adult parasitoids were determined. Two formulations of neem-seed extracts containing azadirachtin and a purified azadirachtin standard were tested at an operational dose and at 10 times the operational dose. At 50 g azadirachtin/ha (operational dose), no significant effects were observed on survival of parasitoid females. At 500 g azadirachtin/ha, female survival after 1 day was significantly reduced by Azatin EC and Neem EC. No reduction was evident with the 100% azadirachtin treatment, suggesting that other components of the formulations were in part responsible for the toxicity to females. Likewise, at 500 g azadirachtin/ha, the number of eggs parasitized was greatly reduced by Azatin EC and slightly reduced by Neem EC but was not reduced by an azadirachtin standard. These reductions in egg parasitism were probably due to the observed effects on female survival. At 500 g azadirachtin/ha, parasitoid developmental success was reduced by all treatments including the azadirachtin standard. Neem EC and Azatin EC at the lower dose also had a small but significant effect on developmental success. Sex ratio of emerging adults was not affected. These results indicate that azadirachtin is compatible with T. minutum during egg parasitism at operational dosages.
Chapter 19 - Rice
- Edited by Dominic Fuccillo, University of Arkansas, Linda Sears, International Plant Genetic Resources Institute, Rome, Paul Stapleton, International Plant Genetic Resources Institute, Rome
-
- Book:
- Biodiversity in Trust
- Published online:
- 22 September 2009
- Print publication:
- 28 August 1997, pp 273-291
-
- Chapter
- Export citation
-
Summary
Rice feeds half the world's people, mainly in Asia. Their food security and crop biodiversity depend upon continued access to seed developed from thousands of locally adapted varieties of Oryza sativa and O. glaberrima that Asian and African farmers have grown for generations, the more than 20 species of wild rice native to Asia, Africa, Latin America and Oceania, and the related genera in the tribe Oryzeae. Worldwide, about 80 million ha of rice are grown under irrigated conditions, the most important rice production system, with average yields of 3-9 t/ha. Athough four CGIAR centres (IRRI, WARDA, CIAT and IITA) hold and use rice germplasm, only IRRI has a global mandate to conserve and improve germplasm. Other centres have regional or continental mandates in Africa and Latin America.
The aggregate population of the less-developed countries grew from 2.3 billion in 1965 to 4.1 billion in 1991. Asia accounted for 59% of the global population, about 92% of the world's rice production and 90% of global rice consumption. Bangladesh, China, India, Indonesia, Myanmar, Thailand and Vietnam are the world's largest rice producers, accounting for about 78% of world production (IRRI 1995). Even with rice providing 35–80% of total calories consumed in Asia and with a slowing of growth in total planted area, production has so far kept up with demand. The world's annual rough rice production, however, will have to increase by almost 70% over the next 35 years to keep up with population growth and income-induced demand for food.