Owing to complex direct and indirect effects, impacts of higher trophic levels on plants is poorly understood. In tropical agroecosystems, ants interact with crop mutualists and antagonists, but ...little is known about how this integrates into the final ecosystem service, crop yield. We combined ant exclusion and introduction of invasive and native-dominant species in cacao agroecosystems to test whether (i) ant exclusion reduces yield, (ii) dominant species maximize certain intermediate ecosystem services (e.g. control of specific pests) rather than yield, which depends on several, cascading intermediate services and (iii) even, species-rich ant communities result in highest yields. Ants provided services, including reduced leaf herbivory and fruit pest damage and indirect pollination facilitation, but also disservices, such as increased mealybug density, phytopathogen dissemination and indirect pest damage enhancement. Yields were highest with unmanipulated, species-rich, even communities, whereas ant exclusion decreased yield by 27%. Introduction of an invasive-dominant ant decreased species density and evenness and resulted in 34% lower yields, whereas introduction of a non-invasive-dominant species resulted in similar species density and yields as in the unmanipulated control. Species traits and ant community structure affect services and disservices for agriculture in surprisingly complex ways, with species-rich and even communities promoting highest yield.
Human activities may influence the diversity of aquatic insects in rivers. This study aims to assess the diversity of aquatic insects and their relation with mercury levels and water quality along ...rivers located near the gold mine in Poboya, Central Sulawesi. The insects were collected at six locations based on human activity levels. At each site, the mercury level of water was measured using atomic absorption spectrophotometry (AAS). In addition, water temperature, acidity, dissolved oxygen, and total dissolved solids were determined. The study recorded 23 species of aquatic insects belonging to 7 orders and 14 families. Mercury levels in the rivers did not exceed the threshold except at two sites and did not affect aquatic insects’ diversity. The diversity of aquatic insects, however, tends to decrease downstream. The diversity of aquatic insects, particularly the Ephemeroptera, Plecoptera, and Trichoptera orders, tended to be higher at the higher dissolved oxygen sites.
An increasing studies related with the detrimental effects of agrochemicals suggested the advantage of biofertilizers and biopesticides uses to support the sustainable farming system. This study ...aimed to evaluate the response of shallot ‘Lembah Palu’ with the application of arbuscular mycorrhizae (AM) and Beauveria bassiana (Bb) under organic farming system. A split-plot experiment was designed to combine Bb at two intervals (every 5 and 10 days) and AM with three rates (0; 5; and 10 g per plant). Leafminer population and infestation, root colonization, root biomass, and shallot yield were observed. Application of the AM and Bb affected shallot production and leafminer infestation, independently. Mycorrhizae application increased the root biomass and yield of shallot but gave negligible effects on population and leafminer attack. The shallot production with no mycorrhizae was significantly lower compared to both mycorrhizae application rates of 5 g and 10 g. The application of B. bassiana every 5 days was more effective in suppressing the population and infestation of leafminers compared to that every 10 day-treatment. The study points out the positive contribution of the mycorrhizae and B. bassiana in the shallot cultivation and supports the implementation of the organic farming system.
Managing ecosystems for carbon storage may also benefit biodiversity conservation, but such a potential 'win-win' scenario has not yet been assessed for tropical agroforestry landscapes. We measured ...above- and below-ground carbon stocks as well as the species richness of four groups of plants and eight of animals on 14 representative plots in Sulawesi, Indonesia, ranging from natural rainforest to cacao agroforests that have replaced former natural forest. The conversion of natural forests with carbon stocks of 227-362 Mg C ha(-1) to agroforests with 82-211 Mg C ha(-1) showed no relationships to overall biodiversity but led to a significant loss of forest-related species richness. We conclude that the conservation of the forest-related biodiversity, and to a lesser degree of carbon stocks, mainly depends on the preservation of natural forest habitats. In the three most carbon-rich agroforestry systems, carbon stocks were about 60% of those of natural forest, suggesting that 1.6 ha of optimally managed agroforest can contribute to the conservation of carbon stocks as much as 1 ha of natural forest. However, agroforestry systems had comparatively low biodiversity, and we found no evidence for a tight link between carbon storage and biodiversity. Yet, potential win-win agroforestry management solutions include combining high shade-tree quality which favours biodiversity with cacao-yield adapted shade levels.
1. Biodiversity data are needed for conservation and management of tropical habitats, but the high diversity of these ecosystems makes comprehensive surveys prohibitively expensive and indicator taxa ...reflecting the biodiversity patterns of other taxa are frequently used. Few studies have produced the necessary comprehensive data sets to assess the quality of the indicator groups, however, and only one previous study has considered the monetary costs involved in sampling them. 2. We surveyed four plant groups (herbs, liverworts, trees, lianas) and eight animal groups (ants, canopy and dung beetles, birds, butterflies, bees, wasps and the parasitoids of the latter two) in 15 plots of 50 × 50 m² each, representing undisturbed rainforest and two types of cacao agroforest in Sulawesi, Indonesia. We calculated three biodiversity measures (α and β diversity; percentage of species indicative of habitat conditions), built simple and multiple regression models among species groups (single groups, combinations of 2—11 groups, averaged relative diversity of all 12 groups), and related these to three measures of survey cost (absolute costs and two approaches correcting for different sampling intensities). 3. Determination coefficients (R² values) of diversity patterns between single study groups were generally low (<0·25), while the consideration of several study groups increased R² values to up to 0·8 for combinations of four groups, and to almost 1·0 for combinations of 11 groups. Survey costs varied 10-fold between study groups, but their cost-effectiveness (indicator potential versus monetary cost) varied strongly depending on the biodiversity aspect taken into account (α or β diversity, single or multiple groups, etc.). 4. Synthesis and applications. We found that increasing the number of taxa resulted in best overall biodiversity indication. We thus propose that the most cost-efficient approach to general tropical biodiversity inventories is to increase taxonomic coverage by selecting taxa with the lowest survey costs.
Bioindicators have been widely accepted as useful tools for monitoring and detecting changes in the environment or habitat condition. By using bioindicators, it is possible to assess the impact of ...human activities on the biota, instead of examining the entire biota. In this paper we analyzed diversity of dung beetles (Coleoptera: Scarabaeidae) across land use gradient inCentral Sulawesi and tested the suitability of dung beetles as bioindicators for environmental changes. Ninety baited pitfall trapswere placed and several habitat parameterswere measured at five land-use types ranging from natural forest to cacao agroforestry systems to open areas in 2009 and 2012. The effectiveness of dung beetles as bioindicators of environmental changes was evaluated by the IndVal method, a method combining the specificity and fidelity of certain species with particular types of habitat or environmental conditions. Surprisingly, the results showed that the diversity of dung beetles in two types of cacao plantations were similar to the forest sites and were significantly higher than the open cultivated area. Of the 16 dung beetles species analyzed only four species could be suggested as indicator (characteristic) species while the majority of collected species were categorized as detector species. Two of them (Copris saundersi and Onthophagus forsteni) were associated with natural forest and cacao agroforestry system, thus were suggested as the indicator of shaded and cooler habitats whereas O. limbatus and O. trituber can be suggested as indicator of unshaded and warmer habitats (bare land area).Keywords: bioindicators, diversity, Scarabaeidae, habitat preferences, IndVal.
1. Avian ecosystem services such as the suppression of pests are considered to be of high ecological and economic importance in a range of ecosystems, especially in tropical agroforestry. However, ...how bird predation success is related to the diversity and composition of the bird community, as well as local and landscape factors, is poorly understood. 2. We quantified arthropod predation in relation to the identity and diversity of insectivorous birds using experimental exposure of artificial, caterpillar-like prey in 15 smallholder cacao agroforestry systems differing in local shade-tree management and distance to primary forest. The bird community was assessed using both mist-netting (targeting active understorey insectivores) and point counts (higher completeness of species inventories). 3. Bird predation was not related to local shade-tree management or overall bird species diversity, but to the activity of insectivorous bird species and the proximity to primary forest. Insectivore activity was best predicted by mist-netting-based data, not by point counts. We identified the abundant Indonesian endemic lemon-bellied white-eye Zosterops Moris as the main driver of prédation on artificial prey. 4. Synthesis and applications. The suppression of arthropods is a major ecosystem service provided by insectivorous birds in agricultural systems world-wide, potentially reducing herbivore damage on plants and increasing yields. Our results show that avian prédation success can be driven by single and abundant insectivorous species, rather than by overall bird species richness. Forest proximity was important for enhancing the density of this key species, but did also promote bird species richness. Hence, our findings are both of economical as well as ecological interest because the conservation of nearby forest remnants will likely benefit human needs and biodiversity conservation alike.
•We tested how flower cover, adjacent homegardens and forest distance influenced bees and yields.•Cucumber yield increased significantly with increasing bee abundance.•Bees were affected on multiple ...spatial scales.•Bees were most abundant with 50% flower cover and surrounded by 50% homegardens.•Distance to forest influenced mostly small bees.
Pollinator populations respond to environmental changes operating on different spatial scales, but the contribution of scale-dependent habitat management to crop pollination and yield-gap reduction is little understood. Here, we analyze how bee abundance and their effects on cucumber production in tropical homegardens is driven by factors measured on three spatial scales; the (1) homegarden scale (flower cover of the focal homegarden); the (2) adjacent-habitat scale (amount of homegarden habitat within a 200m radius around the focal homegarden); and the (3) landscape scale (distance of the focal homegarden to the nearest forest from 0 to 2200m). We also evaluate bee responses according to functional traits such as body size.
We found that bees were affected by factors on multiple spatial scales. On the homegarden scale, the percentage flower cover best predicted pollinator attraction, if, on the adjacent-habitat scale the percentage of surrounding homegardens was at least 20%. On the landscape scale, bee abundance, mainly of small species, increased when homegardens were closer to the forest.
Increasing abundance of flower-visiting bees increased cucumber yield, with solitary bees being the most abundant flower visitors. We predicted that a 50% loss in bee abundance would translate into a 47% yield and associated income decline. Homegardens with a flower cover of 50%, being surrounded by a homegarden area of 50% and being established <100m from the forest can translate in a nine-fold higher yield and income compared to homegardens with low flower cover (<15%), and isolated from other homegardens (<20%) and the forest (>1500m).
Our work suggests that farmers need to be aware of management practices not only at the local and landscape scale but also on the adjacent-habitat scale. Only then farmers can increase wild bee populations to reduce crop yield gaps through pollination services.
ABSTRACT Integrated pest management (IPM) has been recognized as the best solution to minimize the adverse effects of insecticides applied to farmland. This study aims to evaluate the effectiveness ...of the trapping crop system (TCS) and arbuscular mycorrhizae (AM) against leaf miner, an important horticultural pest throughout the world including on shallot crops in Indonesia. In a factorial research design, cucumbers use in TCS was planted in three different pattern: one rows in the center; TC1, two rows in the middle; TC2, and one-row surroundings the shallot; TC3, while AM consists of two levels that are with (M1) and without AM (M2) application. The variables measured were: population and infestation of leaf miners as well as parasitism at the main and trap crops. The results showed that the leaf miners population was significantly reduced by TCS application but had no relation with AM. The leaf miners population decreased by about 40.1% at the TCS compared with the controls. However, the combination of TCS and AM reduced the leaf miner infestation by about 47.5% where TC3M1 showed the best treatment against leaf miners. Increasing of the parasitoids population and parasitism at the shallot and cucumbers as trap crops as well as the shallot resistance against leaf miner may explain the compatibility of TCS and MA to manage the pest. The study denoted the importance of IPM against shallot leaf miners to support sustainable farming system.
Cocoa farmers in Palolo sub-district conducted cocoa cultivation by implementing three cocoa cropping systems, including the cocoa cropping system without using shade trees (A1), using a number of ...permanent shade trees (A2), and using natural forests as the shade trees (A3). The aim of the study was to determine the diversity of arthropods and decreased seed weight in the three cocoa cultivation systems. The sampling of arthropods used pitfall traps, light trap, and Yellow Fan Trap. The found 2684 arthropod individuals represented 12 orders, 47 families and 106 species. Diversity index and abundance index were the highest for cocoa crop ecosystem A2 (2.9 and 13.1). The largest decrease in weight of cocoa seeds was found in the A1 locations (8.34%) and the lowest in the A3 locations (3.61%). We recommend that cocoa cultivation should use protective trees.
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