No abstract

Pollination deficits can compromise fruit yield and quality and have been reported in several fruit crops. It is unknown whether there is a pollination deficit in the production of Korla fragrant pear, Pyrus sinkiangensis, in China, and if so, whether this deficit can be mitigated by the use of managed honeybees (Apis mellifera). We assessed insect communities, flower visitation, pollination deficit and honeybee contribution to pear pollination in Korla fragrant pear orchards in Xinjiang, China. Insect communities were monitored using colored pan traps, and pollination deficit was assessed by comparing fruit set with open pollination to that with hand pollination in orchards without beehives from 2018 to 2021. The contribution of honeybees to pollination was assessed by comparing flower visitation, fruit set and fruit quality in pear orchards with and without beehives in 2020 and 2021. In orchards without beehives, wild bees (72%) were the dominant pollinator group in pan traps, followed by honeybees (15%), moths, hoverflies, butterflies and wasps (Vespidae). Fruit set in these orchards was much lower with open pollination (8 ± 2%) than with hand pollination (74 ± 4%). When comparing pollination in orchards with and without beehives in 2020 and 2021, we found that honeybees were responsible for most of the flower visits in orchards with (96%) and without beehives (66%). Wild bees were responsible for 1% and 6% of flower visits in orchards with and without beehives, respectively. Fruit set was significantly higher in orchards with beehives (38 ± 9%) than in orchards without beehives (12 ± 3%), while fruit set and sugar content were positively associated with pollinator visitation rate. The findings reveal a large pollination deficit in Korla fragrant pear orchards, and show that this deficit can be mitigated using managed honeybees.

BACKGROUND Habitat management such as field‐ or farm‐level diversification can conserve arthropod natural enemies, enhance biological pest control and lower (or suspend) insecticide use in agricultural crops. These approaches however have been underexploited to manage the aphid Aphis gossypii in cotton cropping systems of Xinjiang, China. In this study, we investigated whether the presence of licorice (Glycyrrhiza uralensis) at the field edge benefits generalist predator abundance and aphid biological control in local cotton crops. RESULTS Field trials during 2020 and 2021 showed that licorice strips enhanced the in‐field abundance of generalist predators (primarily ladybeetles) 2.2–4.3 fold during early season, i.e. initial growth before A. gossypii peak infestation pressure. During peak outbreak conditions in July, treatment fields with licorice strips experienced a respective 17.5–61.2% lowered aphid density and 12.3–14.6‐fold higher predator‐to‐aphid abundance ratio (PAR) than control fields. In late season (aphid decline phase) of either year, cotton fields with licorice strips also attained a respective 4.7–9.9 fold higher PAR. Exclusion cage assays quantitatively assessed predator‐mediated A. gossypii biological control and the relative contribution of licorice strips. The biocontrol services index (BSI) was 2.8 times (2020) and 1.4 times (2021) higher at 5 m distances from the licorice strip as compared to control fields. CONCLUSION Licorice strips in the immediate vicinity of cotton fields benefit generalist arthropod predators and improve aphid biological control throughout the cotton cropping season. These findings help to integrate habitat management within integrated pest management (IPM) frameworks in the biggest cotton production region of China. © 2022 Society of Chemical Industry.

Investigation into the organic solar cells (OSCs) with graphene electrode demonstrates that the weak-microcavity (WMC) constructed between the transparent electrode and top metal electrode plays an important role in the absorption properties of the devices. If the WMC structure is not optimized, the absorption of the graphene-based devices cannot surpass that of OSC devices with indium tin oxide electrode. By employing dielectric/graphene/dielectric multilayer to optimize the WMC, the absorption can be improved by a maximum value of 21.1% within a broad wavelength range of 410–636 nm. Correspondingly, an improvement of 12.1% in total absorbed photons is achieved for the device.