Agroecosystems undergo frequent anthropogenic disturbance that may affect the diversity, community, and abundance of natural enemies living there. In the tropics, annual crops such as maize are planted two times (year-round crops) or one time (seasonal crops) per year. Little is known about how natural enemies of insect pests respond to maize agroecosystems planted one vs. two times during each annual cycle. The objective was to investigate the diversity and parasitism of egg parasitoids of the pest Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) in maize agroecosystems planted year-round and seasonally. Potted maize plants with D. maidis eggs were placed within these two maize agroecosystems to attract egg parasitoids during the maize-growing wet season in Mexico. In these two maize agroecosystems, similar levels of diversity were found, using the Shannon-Wiener index (H′). Communities of parasitic wasps were found attacking the eggs of D. maidis in both maize agroecosystems, but there were differences in the composition of these communities. In the year-round maize agroecosystem, Paracentrobia sp. near subflava (Girault) (Hymenoptera: Trichogrammatidae) was the most common, while Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) was most common in the seasonal maize. A greater total abundance and total rate of parasitoid emergence were found in the year-round maize agroecosystem compared with the seasonal maize. In addition, a positive relationship between the number of D. maidis eggs and parasitoid abundance was found in both maize agroecosystems. However, a negative density dependence between the number of D. maidis eggs and the percentage of parasitism was found in both maize agroecosystems.

中文翻译：

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寄生黄蜂在全年和季节性玉米农业生态系统中攻击 Dalbulus maidis（半翅目：蝉科）的多样性和寄生

农业生态系统经常遭受人为干扰，这可能会影响生活在那里的天敌的多样性、群落和丰富度。在热带地区，玉米等一年生作物每年种植两次（全年作物）或一次（季节性作物）。关于害虫的天敌如何对在每个年度周期中种植一两次的玉米农业生态系统作出反应，我们知之甚少。目的是调查全年和季节性种植的玉米农业生态系统中害虫 Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) 卵寄生蜂的多样性和寄生性。在墨西哥玉米生长的雨季，将带有 D. maidis 卵的盆栽玉米植物放置在这两个玉米农业生态系统中，以吸引卵寄生蜂。在这两个玉米农业生态系统中，发现了相似的多样性水平，使用香农-维纳指数 (H')。在两个玉米农业生态系统中都发现寄生蜂群落攻击 D. maidis 的卵，但这些群落的组成存在差异。在全年的玉米农业生态系统中，Paracentrobia sp。近 subflava (Girault) (Hymenoptera: Trichogrammatidae) 是最常见的，而 Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) 在季节性玉米中最常见。与季节性玉米相比，全年玉米农业生态系统中寄生蜂的总丰度和总出现率更高。此外，在两个玉米农业生态系统中发现 D. maidis 卵的数量与寄生蜂丰度之间存在正相关关系。但是，D 的数量之间存在负密度依赖性。