Polycultures and conventional monoculture have different effects on insect pests and natural enemies. Little is known about the parasitoid response to landrace and hybrid plants damaged by insect pests within organic-polyculture agroecosystems vs. monoculture ones. The aim of the present study was to compare the suitability of these agroecosystems for hosting parasitic wasps by evaluating the parasitism rate, parasitoid abundance, and species composition on landrace and hybrid maize races within organic-polyculture and conventional maize agroecosystems. This study was performed within the Mesoamerican region where maize was originally domesticated and where the maize insect pest Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) originated. Maize plants of landrace and hybrid varieties were used to attract egg parasitoids of D. maidis within each of the two agroecosystems; conventional maize monoculture and an organic-polyculture of landrace maize, beans, and squash, which also included weed plants. Four treatments were conducted in this field experiment: 1) landrace-within organic agroecosystem, 2) hybrid-within organic agroecosystem, 3) landrace-within conventional agroecosystem, and 4) hybrid-within conventional agroecosystem. A community of parasitic wasps, of which the micro-wasp Paracentrobia sp. (Hymenoptera: Trichogrammatidae) was the most abundant member, was found attacking the D. maidis eggs in both agroecosystems. The parasitism rate and parasitoid abundance were similar among the four treatments. However, the abundance of parasitoids was greater in the conventional maize monoculture. Bait plants (landrace and hybrid maize) within each agroecosystem did not show differences in either parasitoid abundance or parasitism rate.

中文翻译：

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传统和有机混养玉米农业生态系统中杂交和地方品种玉米植物对寄生蜂的适宜性

混养和常规单养对害虫和天敌的影响不同。关于寄生蜂对有机混养农业生态系统与单一栽培农业生态系统中虫害破坏的地方品种和杂交植物的反应知之甚少。本研究的目的是通过评估有机混养和常规玉米农业生态系统中地方品种和杂交玉米品种的寄生率、寄生蜂丰度和物种组成，比较这些农业生态系统对寄生蜂的适用性。这项研究是在最初驯化玉米的中美洲地区进行的，也是玉米害虫 Dalbulus maidis (DeLong) (半翅目: Cicadellidae) 的起源地。地方品种和杂交品种的玉米植物被用来吸引 D. 两个农业生态系统中的每一个；传统的玉米单一栽培和地方品种玉米、豆类和南瓜的有机混养，其中还包括杂草植物。在该田间试验中进行了四种处理：1）有机农业生态系统内的地方品种，2）有机农业生态系统内的杂种，3）常规农业生态系统内的地方品种，和4）常规农业生态系统内的杂种。寄生蜂群落，其中微蜂 Paracentrobia sp。（膜翅目：Trichogrammatidae）是最丰富的成员，被发现攻击两个农业生态系统中的 D. maidis 卵。四种处理的寄生率和寄生体丰度相似。然而，在传统的玉米单一栽培中，寄生蜂的丰度更高。