Predation Pressure in Tea (Camellia sinensis) Plantations in Southeastern China Measured by the Sentinel Prey Method

Abstract

Tea (Camellia sinensis) is an important food product with thousands of years of human use. Being a non-washable food, no pesticide residues are allowed, which increases the importance of natural means of plant protection. Predation, a component of natural pest control, is an important contributor to this, but its level and sustainability are not known in most of the areas of tea production. We quantified predation intensity using the artificial sentinel prey method in a tea-growing landscape containing remnants of the original forest vegetation in Fujian Province, China. The most common predators were chewing arthropods (49.8% of predation events) and birds (48.1%). Overall, predation rates at the edges of forest fragments (18.9% d-1) were lower than either in fragment interiors (25.4%d−1) or in the surrounding tea plantations (19.2–24.1%d-1). Arthropod predation was higher inside, and at the edge of, forest fragments than within plantations, and generally decreased with increasing distance from a fragment edge, indicating limited spillover of arthropod predators from the native habitat remnants to the cultivated matrix at the local scale. Bird predation, though, showed a different trend: it was lower on the inside of forest fragments than in the tea planation, and bird attack rates increased at increasing distances (up to 40 m) from the forest fragment edge. We also found a reciprocal relationship between attack rates by birds and arthropods, suggesting intra-guild predation. Measures protecting arthropod natural enemies could increase the combined pest suppression effect, contributing to pesticide-free tea production in China.

Diversity of Bird Communities in Tea (Camellia sinensis) Plantations in Fujian Province, South-Eastern China

“…In northern India, four bird species, the Asian-pied Starling (Gracupica contra), Chestnut-tailed Starling (Sturnia malabarica), Jungle Myna (Acridotheres fuscus), and the Red-vented Bulbul (Pycnonotus cafer) are identified as potentially effective biocontrol agents against pest caterpillars [25]. In the studied landscape, we found that birds regularly moved out of the forest fragment, and a concurrent study [29] found an attack rate of 19-25% d −1 on sentinel prey placed on tea plants. The rate of attack increased as the distance to the next forest fragment edge increased.…”

“…In each of the three locations, we selected two forest fragments, and their neighbouring tea gardens. For further details concerning the research sites, see Imboma et al [29].…”

Smaller and Isolated Grassland Fragments Are Exposed to Stronger Seed and Insect Predation in Habitat Edges

“…We assessed the predatory activity of carnivorous insects with dummy green caterpillars of moths made of plasticine, exposed for seven days. This method of sentinel prey is easy to use and appropriate to assess in situ predation pressure [39,49]. Dummy caterpillars were 25 mm long and 5 mm in diameter, and made from light green nontoxic modelling plasticine (Fimo Soft ® , Staedtler Mars GmbH & Co. KG, Nuremberg, Germany).…”

“…Measuring species interactions such as insect and seed predation is challenging. Instead of measuring the function itself, studies often use densities of predators as a proxy [37], which can be misleading [38,39]. Here, we aimed to study the effects of fragmentation (i.e., increasing isolation, decreasing fragment size, and edge effect) directly on predation in two grassland ecosystems.…”

Cropland can support high bird diversity in heterogeneous rural tropical landscapes

“…pest control and pollination, but also disservices, i.e. seed predation (Imboma et al 2020; Morante-Filho and Faria 2017; Wenny et al 2011; Zhang et al 2007).…”