Insect diversity in viticulture - influence of management and landscape

Author: Marvin Kaczmarek, Julius Kühn-Institut

In this research project I am investigating the influence of different management practices, reduced pest management in fungus resistant grapevine varieties (PIWI) and semi-natural habitat structures in the vicinity of vineyards using malaise traps and yellow trays as well as the meta-barcoding service of AIM. The results will be used as a basis for longer-term monitoring within the framework of MonViA, the National Monitoring of Biodiversity in Agricultural Landscapes, to provide information on the importance of local management and landscape structure for biodiversity in vineyards.

Vineyards represent hotspots of biodiversity due to their heat-favorable location. At the same time, viticulture is one of the crops with the highest pesticide applications. Insect biodiversity has declined rapidly in many agricultural landscapes in recent decades. However, it is not known to what extent such negative population trends of species also occur in viticulture. Here, the conditions might have improved in the last decades in the context of integrated pest management and by the establishment of greening in the vineyards.

In 16 landscapes in the Southern Palatinate, which differ in their proportion of near-natural habitats in the vicinity of the vineyards, malaise traps and yellow trays were set up to record insect diversity. In each of these landscapes, either two conventionally or two organically farmed plots were sampled, each planted with a classic or a PIWI grape variety. Compared to the classic varieties, PIWI varieties received only about one-third of the plant protection applications. From April to September 2020, insects were captured, analyzed using meta-barcoding, and classified into OTUs (Operational Taxonomic Units) based on their DNA sequences on the CO1 gene. The number of OTUs per vineyard plot was used as a measure of species diversity. Here, an influence of the type of cultivation - organic or conventional - could not be proven. While PIWIs have a slightly higher species diversity compared to conventional vineyards, it is mainly the surrounding landscape structure that is decisive for insect diversity in viticulture. With an increasing proportion of near-natural habitats, the number of species increases significantly.

In this study, AIM's DNA metabarcoding technology helps me to evaluate the biodiversity in the viticulture ecosystem based on the comprehensive species lists in addition to the species numbers. In the further evaluation of the extensive data from the metabarcoding of the 2020 season and further samples from the following year, I analyze differences in species composition between the landscape sites as well as the occurrence of relevant species. For viticulture, the occurrence of pests and beneficial insects - including, for example, various species of ichneumon flies - is particularly relevant in this respect. In 2020, using metabarcoding, I was able to detect species that are considered pests in viticulture, such as the grape berry moth (Lobesia botrana, BOLD:ACH2178) and the cherry vine silk fly (Drosophila suzukii, BOLD:AAC2499). Furthermore, the occurrence of heat-loving species spreading northwards from the Mediterranean region and of introduced species could be proven. These include, for example, the banded bloodcicada (Cercopis sanguinolenta, BOLD:AAZ8612), originally native to southeastern Europe, and the steel-blue cricket (Isodontia mexicana, BOLD:AAG1683), which originates from America. Especially with regard to longer-term monitoring, metabarcoding offers significant opportunities for analyzing changes in biodiversity. The service of AIM enables me to use these possibilities ideally in ecosystem analysis and insect monitoring through the competent processing and sequencing of the mixed samples and the clear presentation of the results.

Marvin Kaczmarek (JKI), October 2021

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