Effect of Lockdown on the Air Quality of Four Major Cities in Pakistan During the COVID-19 Pandemic

This study attempted to evaluate the effect of lockdown on the air quality of four major cities in Pakistan: Karachi, Lahore, Islamabad, and Peshawar. Particulate matter (PM2.5) concentration and U.S. Environmental Protection Agency Air Quality Index (AQI) were used to determine air quality before and after lockdown. We found that air quality in all the cities improved after lockdown was imposed: PM2.5 concentrations in Karachi and Lahore decreased by 62% and in Peshawar and Islamabad by 57% and 55%, respectively. AQI in Karachi and Islamabad improved from Unhealthy to Moderate and in Peshawar and Lahore from Unhealthy to Unhealthy for Sensitive Groups. Formal complete lockdown in Pakistan was imposed on March 24, 2020, and lasted until May 10, 2020, after which partial or smart lockdown was still in place. Maximum improvement in air quality was observed in April 2020, with concentrations starting to increase in May 2020 following the ease of restrictions.

Geographic potential of the world's largest hornet, Vespa mandarinia Smith (Hymenoptera: Vespidae), worldwide and particularly in North America.

The Asian giant hornet (AGH, Vespa mandarinia) is the world's largest hornet, occurring naturally in the Indomalayan region, where it is a voracious predator of pollinating insects including honey bees. In September 2019, a nest of Asian giant hornets was detected outside of Vancouver, British Columbia; multiple individuals were detected in British Columbia and Washington state in 2020; and another nest was found and eradicated in Washington state in November 2020, indicating that the AGH may have successfully wintered in North America. Because hornets tend to spread rapidly and become pests, reliable estimates of the potential invasive range of V. mandarinia in North America are needed to assess likely human and economic impacts, and to guide future eradication attempts. Here, we assess climatic suitability for AGH in North America, and suggest that, without control, this species could establish populations across the Pacific Northwest and much of eastern North America. Predicted suitable areas for AGH in North America overlap broadly with areas where honey production is highest, as well as with species-rich areas for native bumble bees and stingless bees of the genus Melipona in Mexico, highlighting the economic and environmental necessity of controlling this nascent invasion.