Lao farmers' insecticide use on eggplants (Solanum melongena L.) and its effects on phytophagous arthropods and natural enemies 机翻标题: 暂无翻译,请尝试点击翻译按钮。

作者
Arounsack, Soulinhakhath Steve
摘要
Monitoring pesticide use is required to assess potential ecological and human health risks. In California, little is known of the insecticide use patterns of Lao farmers because the majority of them do not report. To study the effects of Lao farmers' insecticide use on phytophagous arthropods and natural enemies, we examined eggplants (Solanum melongena L.) because it is an important crop for many Asian farmers. Major objectives of this study: (1) documenting Lao farmers' insecticide use on eggplants, (2) quantifying the seasonal occurrence of insect fauna on eggplants and (3) investigating the effects of Lao farmers' insecticide use on phytophagous arthropods and natural enemy densities. Unsprayed and sprayed eggplant plots in Fresno County were examined for two years (2004 and 2005) during the typical eggplant season (May to October). Results from inperson surveys showed that unregistered Lao farmers regularly applied esfenvalerate at triple the label rates. The pesticide use report (PUR) database revealed that Lao farmers accounted for the majority of Fresno County's applications and cumulative acres treated by esfenvalerate and oxamyl by 2004. Faunal surveys performed with a gas-powered suction device revealed 7 orders and 18 families. Of the 25 total species identified, 17 were natural enemies and 8 were phytophagous pests. Orius tristicolor, Hippodamia convergens, flies (family Tachinidae), Geocoris spp., Diaeretiella rapae, and Chrysoperla spp. were the natural enemies found in the greatest quantities. Tetranychus spp., Myzus persicae , and Lygus hesperus were the major phytophagous arthropods. A repeated-measured ANOVA showed that Myzus persicae infestation was significantly higher on sprayed fields and the densities of two natural enemies, Zelus renardii, and Geocoris punctipes, were significantly higher on unsprayed plots in 2004. No significant differences were found in the densities of phytophagous pests or natural enemies in 2005. In conclusion, Lao farmers' high use of esfenvalerate decreased the densities of two important natural enemies while not significantly suppressing phytophagous pest densities, suggesting that the use of pyrethoids was not an efficient use of resources and could even be harmful to natural enemies. This inefficiency underscores the need for Lao farmers to reevaluate their insecticide use and obtain proper training.
机翻摘要
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关键词
Ecology;Plant propagation;Entomology
页数
115
出版日期
2019-06-25
学位授予单位
University of California, Davis
学位年度
2006
学位
Ph.D.
语言
eng
院系
Ecology;Plant propagation;Entomology
导师
Zhang, Minghua
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