Influence of the vegetation management of the leeves in irrigated rice organic in diversity of Hymenoptera parasitoids.

P. R. Simões-Pires,S. M. Jahnke,L. R. Redaelli

doi:10.1590/1519-6984.06215

P. R. Simões-Pires, S. M. Jahnke + Show 1 more

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https://doi.org/10.1590/1519-6984.06215

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Abstract

Among the natural enemies of insect pests in rice fields, parasitoids are especially notable. To better understand the space-time dynamics of these insects, the objectives of this study were to describe and compare groups of parasitoids in organic irrigated rice fields using two management approaches for levee vegetation, and to relate them to the phenological stages of rice cultivation (the seedling, vegetative, and reproductive stages). The samples were taken in a plantation located in Viamão, RS, Brazil. The total area of 18 ha was divided into two parts: a no-cut (NC) subarea in which the wild vegetation of the levees was maintained, and a cut (C) subarea in which the levee vegetation was cut monthly. In each subarea, four Malaise traps considered as pseudo-replicas were installed and remained in the field for 24 hours at each sampling location. Collections occurred twice a month from the beginning of cultivation (October 2012) until harvest (March 2013). A total of 3,184 Hymenoptera parasitoids were collected: 2,038 individuals in the NC subarea and 1,146 in the C subarea. We identified 458 morphospecies distributed in 24 families. Mymaridae was the most abundant and Eulophidae was the richest in both subareas. A total of 198 morphospecies was shared between the subareas, including Platygastridae, Eulophidae, and Mymaridae, which were the families with the highest number of shared species. The richness and abundance of parasitoids varied according to their phenological developmental stages, with peak abundance registering during the vegetative period. The Morisita index identified three groupings, indicating a similarity that was related to the three phases of rice growth and development: seedling, vegetative and post-harvest.

Highlights

Rice (Oryza sativa L.) can be cultivated in highlands, as it is suitable for flooding, and it can be cultivated in stormwater plains (Bambaradeniya and Amerasinghe, 2003); more than 75% of rice production is from an irrigated crop system (Pereira et al, 2005)
Pest insects are present in rice production areas all over the world, especially in irrigated crop systems and in stormwater plains, which present temperatures and humidity levels favorable for their proliferation (Yasumatsu and Torh, 1968)
The greatest number of Hymenoptera parasitoids caught in subarea NC was expected and shows the importance of the wild vegetation as an alternative habitat in irrigated rice, as it provides different resources throughout the crop cycle (Landis et al, 2000; Gurr et al, 2003)

Summary

Introduction

Rice (Oryza sativa L.) can be cultivated in highlands, as it is suitable for flooding, and it can be cultivated in stormwater plains (Bambaradeniya and Amerasinghe, 2003); more than 75% of rice production is from an irrigated crop system (Pereira et al, 2005). In order to control pests, many methods can be used to implement agroecosystems that are economically and ecologically sustainable, creating opportunities to increase the abundance and efficiency of many natural enemies (Bueno and Van Lenteren, 1999). One of these methods includes employing conservation biological control, which aims – through habitat management – to turn to available alternative food, such as nectar, pollen, and honeydew. The main parasitoids are the microhymenopteran, which are similar to small wasps that have a preference for putting their egg masses in caterpillars’ bodies and aphids (Freitas et al, 2010)

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