Pollination in Agroecosystems: A Review of the Conceptual Framework with a View to Sound Monitoring

Island-wide removal of honeybees reveals exploitative trophic competition with strongly declining wild bee populations

High densities of managed honeybees (Apis mellifera) can threaten wild bees through exploitative competition, thus leading to population declines of the latter. Although reviews have outlined key steps to demonstrate these impacts-measuring resource overlap, changes in wild bee behavior, and population trends-studies that comprehensively address these aspects are virtually absent. We were granted access to the entire protected island of Giannutri (2.6 km2) and to the apiary (18 hives) located there during the early phase of coexistence between honeybees and wild bees. Using the island as an open-air laboratory, we experimentally manipulated honeybee pressure by closing the hives on selected days during the peak of the wild bee foraging period. In the plants most visited by pollinators, even short-term honeybee removals (11 h per day) increased nectar volume (∼60%) and pollen availability (∼30%). In the absence of honeybees, target wild bees (Anthophora dispar and Bombus terrestris) became dominant in the insect-plant visitation network, and the potential apparent competition significantly decreased. Accordingly, both species intensified their foraging activity and increased nectar suction time, a recognized proxy for the quantity of probed nectar, and Bombus terrestris also shortened the time of pollen searching. Transect monitoring revealed an alarming ∼80% decline in both species over 4 years, consistent with honeybee monopolization of floral resources, thus reducing availability for wild pollinators and altering their foraging budget. These findings underscore the risks of introducing high densities of honeybees into protected areas and emphasize the need for rigorous preventive ecological assessments.

Do Patches of Flowering Plants Enhance Insect Pollinators in Apple Orchards?

Apples depend on insect pollination but intensification of agriculture jeopardizes pollination services in agroecosystems. Concerns about the dependency of crop pollination exclusively on honey bees increase the interest in agricultural practices that safeguard wild pollinators in agroecosystems. The purpose of the study was to assess the potential of floral resource provision in apple orchards to enhance the conservation of hymenopterous pollinating insects and potentially the pollination service to the crop. For this reason, flowering plant mixtures sown in patches inside apple orchards were tested against wild plant patches. Pollinator taxa recorded on the sown and wild plant patches were honey bees, wild bees (Andrena, Anthophora, Eucera, Halictus, Lasioglossum, Megachilidae on both; Systropha only on wild plants; Bombus, Hylaeus, Sphecodes, Nomada, Xylocopa only on sown mixture), syrphids, bee flies. The most abundant pollinator of apple was A. mellifera but wild bees were also recorded (Andrena, Anthophora, Bombus, Xylocopa, Lasioglossum, Megachilidae). The sown mixture attracted a more diverse taxa of pollinators and in greater numbers compared to the weed flora, but it did not have an effect on pollinators visiting apple flowers. Groundcover management with patches of suitable flowering mixtures can enhance pollinator conservation in apple orchards.

Agriculture and Pollinating Insects, No Longer a Choice but a Need: EU Agriculture’s Dependence on Pollinators in the 2007–2019 Period

One of the new objectives laid out by the European Union’s Common Agriculture Policy is increasing environmental sustainability. In this paper we compare the degree of average dependence index for each member state (ADIMS) in EU28 from 2007 to 2019 in order to verify the following: (1) whether there was a difference in this index when comparing two CAP periods—(a) from 2007 to 2013 and (b) from 2014 to 2019—and (2) which crops had a larger effect on the ADIMS. The study showed no significant variation in the average ADIMS at EU level between the first (2007–2013) and second (2014–2019) CAP periods. The AIDMS index highlighted three types of EU agriculture: (1) agriculture in Eastern Europe, including Bulgaria, Hungary, Romania and Slovakia, characterized by a high level of ADIMS (10.7–22) due to the widespread cultivation of oil crops as rapeseed and sunflower; (2) Mediterranean agriculture including Portugal, Spain, Italy, Croatia, Greece, Malta, Cyprus and France with lower AIDMS levels (5.3–10.3) given their heterogeneous crop portfolios with different degrees of dependence on animal pollination (almond, soy, rapeseed, sunflower and tomatoes) and (3) continental agriculture including Germany, Austria, Slovenia, Poland, the Czech Republic, Baltic countries, Benelux, Finland, Sweden and Ireland, which are characterized by the lowest ADIMS level (0.7–10.6) due to the widespread cultivation of cereals (anemophily and self-pollination) which increase the denominator of the index. The study suggests that a sustainable management of the agroecosystem will be possible in the future only if CAP considers pollinators’ requirements by quantifying the timing and spatial food availability from cultivated and uncultivated areas.

Local Actions to Tackle a Global Problem: A Multidimensional Assessment of the Pollination Crisis in Chile

In the last decades, pollinators have drastically declined as a consequence of anthropogenic activities that have local and global impacts. The food industry has been expanding intensive agriculture crops, many of them dependent on animal pollination, but simultaneously reducing native pollinator habitats. Chile is a good example of this situation. Chile is becoming an agro-alimentary powerhouse in Latin America, where intensive agriculture expansion is performed at the expense of natural lands, posing a major threat to biodiversity. Here, we discussed the drivers responsible for the decline of pollinators (including habitat loss, pesticides, invasive species, and climate change) and its synergistic effects. This is particularly critical considering that Chile is a hotspot of endemic bee species locally adapted to specific habitats (e.g., Mediterranean-type ecosystems). However, there is a lack of data and monitoring programs that can provide evidence of their conservation status and contribution to crop yields. Based on our analysis, we identified information gaps to be filled and key threats to be addressed to reconcile crop production and biodiversity conservation. Addressing the local context is fundamental to undertake management and conservation actions with global impact.