Effect of the strip cropping system of potato and clover on diversity of natural enemies of Leptinotarsa decemlineata Say and damage caused by the pest

Dehghani Kargan, Vahid (2017) Effect of the strip cropping system of potato and clover on diversity of natural enemies of Leptinotarsa decemlineata Say and damage caused by the pest. Masters thesis, University of Mohaghegh Ardabili.

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Text (تأثیر سیستم های کشت نواری سیب زمینی و شبدر در تنوع گونه ای دشمنان طبیعی سوسک ‌کلرادوی سیب‌زمینی، Leptinotarsa decemlineata Say و میزان خسارت این آفت) Vahid Dehghani Kargan.pdf Download (738kB) | Preview

Abstract

The Colorado potato beetle, Leptinotarsa decemlineata (Say) is one of the most important pests of potato in Iran. In this research, the population density of L. decemlineata, the relative abundance and species diversity of natural enemies of this pest were studied in four types of strip cropping systems: a) 3 rows potato-3 rows clover, b) 6 rows potato-3 rows clover c) 9 rows potato-3 rows clover, and d) sole cropping of potato in Ardabil region during 2017. The population density of L. decemlineata (egg clusters, eggs, larvae and adults) was lowest in cropping system of 3 rows potato-3 rows clover and highest in the sole cropping of potato. Chrysoperla carnea (Stephens) and species of Coccinellids including Hipodamia convergens Guernmenevelle, Coccinella septempunctata (L.) and Hippodamia variegata (Goeze) had the highest percentage of relative abundance among the active natural enemies of this pest on aerial parts of plant. The abundance of these predators (C. carnea and coccinellids) in four cropping systems tested showed a pattern of descending order: 3 rows potato-3 rows clover, 6 rows potato-3 rows clover, 9 rows potato-3 rows clover and sole cropping of potato. The Shannon diversity index (H’) for active predators of this pest on aerial parts of plant was highest in 3 rows potato-3 rows clover and lowest in sole cropping of potato. No significant differences were found between the Shannon evenescens indices (E) of these predator species among treatments. In this research, terrestrial predator species of L. decemlineata including one species Opiliones, spiders and carabid beetles were collected using pitfall trap and identified. The values of Shannon diversity and evenescens indices of terrestrial predators in strip cropping systems of potato with clover were significantly more than sole cropping of potato. Based on Morisita-Horn index, the lowest species similarity values of natural enemies were observed between systems of 3 rows potato-3 rows clover and the sole cropping of potato. Also, the highest ones were obtained between strip cropping systems of 3 rows potato-3 rows clover and 6 rows potato-3 rows clover. The percentage of fresh tubers weight loss was significantly lower in strip cropping systems of potato and clover compared with the sole cropping of potato. Also among multiple cropping systems, the lowest percentage of fresh tubers weight loss was obtained in pattern of 3 rows potato-3 rows clover. Based on the results of this research, it can be concluded that strip cropping of potato with clover (especially 3 rows potato-3 rows clover) has an important role in increasing of abundance and diversity of predators and decreasing of L. decemlineata density.

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