Combination of generalist predators, Nesidiocoris tenuis and Macrolophus pygmaeus, with a companion plant, Sesamum indicum: What benefit for biological control of Tuta absoluta?

Ramzi Mansour,Kouassi Arthur J Konan,Ricardo Ramirez-Romero,San-Whouly M Ouali-N’Goran,Lucie S Monticelli,Nicolas Desneux,Thibaud Martin

doi:10.1371/journal.pone.0257925

Abstract

Tuta absoluta is one of the most damaging pests of tomato crops worldwide. Damage due to larvae may cause up to 100% loss of tomato production. Use of natural enemies to control the pest, notably predatory mirids such as Nesidiocoris tenuis and Macrolophus pygmaeus, is increasingly being promoted. However, considering the potential damage caused to tomatoes by these omnivorous predators in the absence of T. absoluta, an alternative solution could be required to reduce tomato damage and improve the predators’ performance. The use of companion plants can be an innovative solution to cope with these issues. The present study aimed to determine the influence of companion plants and alternative preys on the predators’ performance in controlling T. absoluta and protecting tomato plants. We evaluated the effect of predators (alone or combined) and a companion plant (sesame (Sesamum indicum)) on T. absoluta egg predation and crop damage caused by N. tenuis. The influence of an alternative prey (Ephestia kuehniella eggs) on the spatial distribution of predators was also evaluated by caging them in the prey presence or absence, either on tomato or sesame plants or on both. We found that the presence of sesame did not reduce the efficacy of N. tenuis or M. pygmaeus in consuming T. absoluta eggs; hatched egg proportion decreased when N. tenuis, M. pygmaeus, or both predators were present. More specifically, this proportion was more strongly reduced when both predators were combined. Sesame presence also reduced necrotic rings caused by N. tenuis on tomato plants. Nesidiocoris tenuis preferred sesame over tomato plants (except when food was provided only on the tomato plant) and the upper part of the plants, whereas M. pygmaeus preferred tomato to sesame plants (except when food was provided only on the sesame plant) and had no preference for a plant part. Combination of predators N. tenuis and M. pygmaeus allows for better coverage of cultivated plants in terms of occupation of different plant parts and better regulation of T. absoluta populations. Sesamum indicum is a potential companion plant that can be used to significantly reduce N. tenuis damage to tomatoes.

Highlights

The South American tomato pinworm, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is a key pest of tomato crops (Solanum lycopersicum L.) worldwide [1,2,3,4,5,6,7]
In this study we evaluated the impact of the presence of food on the spatial distribution of N. tenuis and M. pygmaeus developing on tomato (T) and sesame (S) plants with or without E. kuehniella eggs (E)
The proportion of hatched eggs of T. absoluta varied significantly depending on the simultaneous presence or not of N. tenuis and M. pygmaeus (Table 1, Fig 1)

Summary

Introduction

The South American tomato pinworm, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is a key pest of tomato crops (Solanum lycopersicum L.) worldwide [1,2,3,4,5,6,7]. The spraying of chemical insecticides in high quantities remains a preferred pest management method and ensures better tomato production [11, 12]. This practice promotes selection of resistant pest populations [13, 14], can generate detrimental side effects on the environment, affects beneficial arthropods [15,16,17,18,19,20] and is not always effective against T. absoluta because of resistance developed to several active substances [21, 22]. There has been a growing interest for generalist predators because of their high adaptation and widespread success compared to other more specialized natural enemies [29]

Methods

Results

Conclusion