Population Numbers and Physiological Response of an Invasive and Native Thrip Species Following Repeated Exposure to Imidacloprid.

Xiaoming Zhang,Guohua Chen,Zhengyue Li,Changxiong Hu,Ru Li,Haiyun Xu,Zhixing Chen

doi:10.3389/fphys.2020.00216

Abstract

Frankliniella occidentalis and F. intonsa are devastating pest insects that target Rosa rugosa, Chrysanthemum morifolium, and Phaseolus vulgaris, which are important economical horticultural plants in China. Meanwhile, R. rugosa and C. morifolium are important cash plants in Kunming, South China. We focus on the population performance of these two thrips species on these three host plants with or without repeated exposure to imidacloprid in Kunming. In the field, the population numbers of F. occidentalis developed faster and were larger on these three sampled host plants, especially under imidacloprid exposure, compared with F. intonsa. The activity of the detoxifying enzymes (CarE, AchE, and MFO) and the antioxidant enzymes (CAT and POD) in both thrips species were significantly enhanced under imidacloprid exposure, whereas the activities of SOD in both thrips were significantly decreased on these three host plants, compared with the control. Overall, enzyme activity of F. occidentalis showed a greater increase than that observed in F. intonsa in most cases, which could be exploited in further studies on thrips resistance management.

Highlights

The western flower thrips [Frankliniella occidentalis (Pergande)] (Thysanoptera: Thripidae) was first reported in 1895 in California, United States
From 2014 to 2017, we investigated the population dynamics of F. occidentalis and F. intonsa on all three flowers of kidney bean (P. vulgaris) cultivar ‘Jiulibai,’ chrysanthemum (C. morifolium) cultivar ‘Shenma,’ and rose (R. rugosa) cultivar ‘Corolla’ at three sites (Songyang Township Songming County, 25◦21 34.55 N, 102◦58 55.19 E; Xiaojie Township Songming County, 25◦20 45.71 N, 103◦05 58.91 E; and Dounan Township Chenggong district, 24◦54 54.06 N, 102◦47’23.60 E) in Kunming city, Yunnan Province, China
In the laboratory, the activity of the detoxifying enzymes CarE, AchE, mixed-function oxidases (MFO), and antioxidant enzymes CAT and POD of these two thrips increased after imidacloprid exposure, suggesting that the constant use of imidacloprid for controlling in the invasive species F. occidentalis might exert an important impact on increased proportion of population in thrips, leading to population outbreaks in the field, which needs to be further studied

Summary

Introduction

The western flower thrips [Frankliniella occidentalis (Pergande)] (Thysanoptera: Thripidae) was first reported in 1895 in California, United States. It is an invasive species and range expansion has meant that it is the dominant thrip species in most areas in which it has invaded (Morse and Hoddle, 2006; Baez et al, 2011). Flowers show premature senescence when F. intonsa populations reach high numbers on hosts (Han et al, 2015) Both thrips species share many vegetables, fruit trees, flowers, and other crop hosts, as well as feed on the flowers and young parts of plants. The control of F. occidentalis and F. intonsa mainly depends on chemical control, and the use of a large number of chemical insecticides has led to the rapid rise of resistant populations and the reemergence of F. occidentalis population (Chen et al, 2011; Zhang et al, 2017b)

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