Toxicity, Sublethal and Low Dose Effects of Imidacloprid and Deltamethrin on the Aphidophagous Predator Ceratomegilla undecimnotata (Coleoptera: Coccinellidae).

Panagiotis J Skouras,Marina Mprokaki,Costas Delis,Vasilios Demopoulos,George J Stathas,Anastasios I Darras,John T Margaritopoulos

doi:10.3390/insects12080696

Abstract

Simple SummaryChemical insecticides are used to control agricultural pests all over the world. However, extensive use of chemical insecticides can be harmful to human health and negatively impact the environment and biological control agents. We studied the toxicity and sublethal effects of imidacloprid and deltamethrin on the aphidophagous coccinellid predator Ceratomegilla undecimnotata (Coleoptera: Coccinellidae). We evaluated one low (LD30) and one sublethal dose (LD10) for both insecticides. Lethal and sublethal effects of both insecticides negatively affected survival, development, reproduction, and longevity, and reduced the intrinsic (r) and finite (λ) rate of increase and the net reproduction rate (R0) of treated populations compared to the control. Our findings indicate that the use of imidacloprid and deltamethrin in combination with C. undecimnotata in the context of IPM should be taken with caution due to the toxic effects of the chemicals in the biocontrol agent under laboratory conditions.Ceratomegilla undecimnotata (Coleoptera: Coccinellidae) is a common aphidophagous coccinellid predator used in biological control against aphid pests. Knowing toxicity, lethal, and sublethal effects of insecticides on natural enemies is essential in order to incorporate them into Integrated Pest Management (IPM). In the present study, the lethal and sublethal effects of imidacloprid and deltamethrin were evaluated on the fourth instar larvae of C. undecimnotata and subsequently on the full life cycle. Our results strongly suggest that sublethal and low doses of imidacloprid and deltamethrin at LD10 and LD30 affected fourth instar larvae duration time, adult preoviposition period, total preoviposition period, and fecundity. Moreover, the intrinsic (r) and finite (λ) rate of increase and the net reproduction rate (R0) significantly decreased in populations treated with imidacloprid compared to the control population. The data clearly suggest that imidacloprid and deltamethrin have a negative influence on population growth parameters of C. undecimnotata at sublethal and low doses and, therefore, these insecticides should be used with caution within the context of IPM.

Highlights

Coccinellids are among the most important predators against many pests including aphids, coccids and mites [1]
The present study investigated the toxicity, sublethal, and low dose effects of imidacloprid and deltamethrin on C. undecimnotata including demographic parameters and survival rates
The results demonstrate that the development time of fourth instar larvae was significantly (p < 0.01) prolonged in the imidacloprid groups (LD10 = 5.22 days and LD30 = 5.31 days) compared to the control (4.06 days)

Summary

Introduction

Coccinellids are among the most important predators against many pests including aphids, coccids and mites [1]. The predatory ladybird beetle Ceratomegilla undecimnotata (Schneider) (Coleoptera: Coccinellidae) is one of the most common ladybird species in Greece [2,3] and preys only on a few aphid species, such as Myzus persicae (Sulzer) and Aphis fabae Scopoli (Hemiptera: Aphididae) [4]. Imidacloprid is a broadspectrum neonicotinoid insecticide acting against piercing/sucking insects, such as aphids, whiteflies, leafhoppers, and various coleopteran pests. It can be applied in a variety of ways, such as sprays, root drenches, and seed dressing [7]. As a common alternative to neonicotinoids, pyrethroids act by binding to the voltage gate sodium channel and is used against pests like Diptera and Hemiptera, especially Aphids, Lepidoptera and Coleoptera [9,10]. Deltamethrin is a type II pyrethroid insecticide used against many agricultural and non-agricultural pest [9]

Methods

Discussion

Conclusion