Bradysia aff. impatiens and Bradysia aff. ocellaris in the semi-hydroponic strawberry production system in Southern Brazil

Adriane Da Fonseca Duarte,Patrícia Da Silva Grinberg,Uemerson Silva Da Cunha,Juliano Lessa Pinto Duarte

doi:10.1590/0103-8478cr20210268

Adriane Da Fonseca Duarte, Patrícia Da Silva Grinberg + Show 2 more

Open Access

https://doi.org/10.1590/0103-8478cr20210268

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Abstract

ABSTRACT: Soilless cultivation of strawberry is in expansion in Brazil due to factors like the reduction of phytosanitary problems and the possibility of extending the crop period, as well as the ergonometric facility for management of the culture. However, black fungus gnats (Sciaridae, Diptera) are ubiquitous pests in the greenhouse production system, causing direct and indirect damage to plants. ThIS study evaluated the occurrence of black fungus gnats species in semi-hydroponic cultivation of strawberry and to identify the species, as well as to describe the symptoms in infested plants. The research was developed in commercial productions of strawberry, in five municipalities (Arroio do Padre, Canguçu, Capão do Leão, Pelotas and Turuçu) during July to December 2017, where adult samples were collected twice a month, with petri dish traps containing water and neutral detergent placed inside the greenhouses between the plants. A total of 2030 adult gnats belonging to two species were collected. Bradysia aff. impatiens, accounted with 90.79% of the total, and Bradysia aff. ocellaris, accounted with 9.21%. In order to assist the correct determination of species, males of both species were identified and illustrated. With respect to the symptoms observed during the research, it was possible to verify since the wilted crown of plants to the death of plants, which were confirmed by the presence of larvae in the root system. As the occurrence of these insects is recent in strawberry, there is no pesticide registered in Brazil, so management strategies (cultural, physical, and sanitary) also are discussed.

Highlights

Strawberry planted area in Brazil reaches about 4.000 hectares and has an estimated production of more than 105 thousand tons per year (RESENDE, 2018)
Sciaridae gnats are very common in greenhouses, nurseries, mushroom farms and other environments with high level of organic matter, since sciarid larvae are major primary decomposers of plant debris (MOHRIG et al, 2012)
When the plants are still not well established, the root system is more susceptible to damage, so it is very important to reduce the population of sciarid gnats at this stage, strengthening the need to implement integrated pest management, through the monitoring with yellow adhesive traps

Summary

Introduction

Strawberry planted area in Brazil reaches about 4.000 hectares and has an estimated production of more than 105 thousand tons per year (RESENDE, 2018). Strawberry may be cultivated in soil or soilless systems (semi-hydroponic system), being cultivated mainly in the soil by Brazilian producers. In this production system the susceptibility of most strawberry cultivars to soil-borne pathogens is high (JAFARNIA et al, 2010; PALENCIA et al, 2016), what increases the excessive use of pesticides by producers (CECATTO et al, 2013). The support base for the substrate may be in tubular plastic packaging, fiber cement tiles, PVC gutters, or wood, where the substrates (organic, wooded rice husk, sand or coconut fiber) are placed free of soil pathogens (GONÇALVES et al, 2016) besides providing a suitable microclimate for plants

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