Routes of Pesticide Exposure in Solitary, Cavity-Nesting Bees

Declines of pollinator health and their populations continue to be commercial and ecological concerns. Agricultural practices, such as the use of agrochemicals, are among factors attributed to honey bee (Apis mellifera L. (Hymenoptera: Apidae)) population losses and are also known to have negative effects on populations of managed non-Apis pollinators. Although pesticide registration routinely requires evaluation of impacts on honey bees, studies of this social species may not reveal important pesticide exposure routes where managed, solitary bees are commonly used. Studies of solitary bees offer additional bee models that are practical from the aspect of availability, known rearing protocols, and the ability to assess effects at the individual level without confounding factors associated with colony living. In addition to understanding bees, it is further important to understand how pesticide characteristics determine their environmental whereabouts and persistence. Considering our research expertise in advancing the management of solitary bees for crop pollination, this forum focuses on routes of pesticide exposure experienced by cavity-nesting bees, incorporating the relative importance of environmental contamination due to pesticide chemical behaviors. Exposure routes described are larval ingestion, adult ingestion, contact, and transovarial transmission. Published research reports of effects of several pesticides on solitary bees are reviewed to exemplify each exposure route. We highlight how certain pesticide risks are particularly important under circumstances related to the cavity nesters

Ecology and economics of using native managed bees for almond pollination

Native managed bees can improve crop pollination, but a general framework for evaluating the associated economic costs and benefits has not been developed. We conducted a cost–benefit analysis to assess how managing blue orchard bees (Osmia lignaria Say [Hymenoptera: Megachildae]) alongside honey bees (Apis mellifera Linnaeus [Hymenoptera: Apidae]) can affect profits for almond growers in California. Specifically, we studied how adjusting three strategies can influence profits: (1) number of released O. lignaria bees, (2) density of artificial nest boxes, and (3) number of nest cavities (tubes) per box. We developed an ecological model for the effects of pollinator activity on almond yields, validated the model with published data, and then estimated changes in profits for different management strategies. Our model shows that almond yields increase with O. lignaria foraging density, even where honey bees are already in use. Our cost–benefit analysis shows that profit ranged from −US$1,800 to US$2,800/ acre given different combinations of the three strategies. Adding nest boxes had the greatest effect; we predict an increase in profit between low and high nest box density strategies (2.5 and 10 boxes/acre). In fact, the number of released bees and the availability of nest tubes had relatively small effects in the high nest box density strategies. This suggests that growers could improve profits by simply adding more nest boxes with moderate number of tubes in each. Our approach can support grower decisions regarding integrated crop pollination and highlight the importance of a comprehensive ecological economic framework for assessing these decisions

A Nonlethal Method to Examine Non-Apis Bees for Mark-Capture Research

Studies of bee movement and activities across a landscape are important for developing an understanding of their behavior and their ability to withstand environmental stress. Recent research has shown that proteins, such as egg albumin, are effective for mass-marking bees. However, current protein mass-marking techniques require sacrificing individual bees during the data collection process. A nonlethal sampling method for protein mark-capture research is sorely needed, particularly for vulnerable, sensitive, or economically valuable species. This study describes a nonlethal sampling method, in which three non-Apis bee species (Bombus bifarius Cresson [Hymenoptera: Apidae], Osmia lignaria Say [Hymenoptera: Megachilidae], and Megachile rotundata Fabricius [Hymenoptera: Megachilidae]) were tested for a unique protein marker by immersing them momentarily in saline buffer and releasing them. Results showed that an egg albumin-specific enzyme-linked immunosorbent assay was 100% effective at detecting the protein on bees that were sampled nonlethally. Furthermore, this sampling method did not have an impact on bee survivorship, suggesting that immersing bees in buffer is a reliable and valid surrogate to traditional, destructive sampling methods for mark-capture bee studies

CropPol: a dynamic, open and global database on crop pollination

Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e. berry weight, number of fruits and kg per hectare, among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), Northern America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). Sampling spans three decades and is concentrated on 2001-05 (21 studies), 2006-10 (40), 2011-15 (88), and 2016-20 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should be shared under the same license terms (CC BY-NC-SA). This article is protected by copyright. All rights reserved

Mean attempts to enter her nest and other nests by <i>Osmia lignaria</i> females before and after treatment applications.

<p>Means within each treatment with different letters are significantly different (<i>P</i> < 0.05).</p

ANOVA results for the treatment effects on the pollen-collecting trip times, mud-collecting trip times, cell production rates per day, and the number of nest recognition attempts made to enter her own and other nests by <i>Osmia lignaria</i> females in cages in Lost Hills, California in 2011.

<p>ANOVA results for the treatment effects on the pollen-collecting trip times, mud-collecting trip times, cell production rates per day, and the number of nest recognition attempts made to enter her own and other nests by <i>Osmia lignaria</i> females in cages in Lost Hills, California in 2011.</p

Mean pollen-collecting trip times by <i>Megachile rotundata</i> females before and after treatment applications.

<p>Means within each treatment with different letters are significantly different (<i>P</i> < 0.05).</p