This is a well-designed and executed study, and a nicely written manuscript. I think the subject matter and results are significant enough to be considered for publication in Proc B. However, before this can happen the authors need to address a number of comments outlined below:

L46: suggest you change “grower” to “growers” here.

L47-49: I suggest you include a citation of Garibaldi et al. (2013) here, alongside references to Artz and Nault 2011; Park et al. 2016; Pfister et al. 2017; Campbell et al. 2018; Rollin and Garibaldi 2019.

L54-57: I recommend including a reference to Rundlöf et al. (2015) here, alongside references to Woodcock et al. 2016, Stuligross and Williams 2020 and Bloom et al. 2021.

L57-60: It would seem to be relevant here to consider direct impacts of insecticide exposure on the provision of pollination services by insects. For example, Stanley et al. (2015) showed a significant reduction in apple flower visitation, pollen collection by bumblebees and crop seed set in response to exposure to a neonicotinoid insecticide.

L69-80: In this section outlining the importance of bee pollination of watermelons, I was surprised not to see earlier relevant work included: for example Kremen et al. (2002; 2004).

L76-80: How important are cucurbit specialist bees, such as the hoary squash bee (Eucera pruinosa), for the pollination of watermelons? These seem to be very significant pollinators of pumpkin and squash in N. America (e.g. McGrady et al. 2019; Willis Chan & Raine 2021a, b).

L141-142: “‘Open pollinated’ flowers were left unbagged for a total of 24 hours
beginning at 0700am and ending at 0700am the following day.” When do watermelon flowers open and when do pistils become receptive to pollen? Some cucurbit crop flowers open around (or even) before dawn and can be visited very early. As such, I think it would be important to add a bit more information about the floral biology of this crop here, and also justify why you picked 7am as the time to unbag the flowers in your open pollination treatment.

L172-174: “Prior to row covering, the ‘0 beetles per plant’ treatment received a water
drench of Wrangler® insecticide (imidacloprid; Loveland Products, Inc., Greeley, CO,
USA) at transplant at a rate of 10 fl. oz/ac (0.35 kg/ha) to remove ambient beetles.” Imidacloprid soil drenches have been shown to have significant impacts on the foraging, nesting and reproduction of ground-nesting solitary bees, in particular the cucurbit specialist pollinators (E. pruinosa)(Willis Chan & Raine 2021c). Did you see any evidence of bee nesting activity in/ around your experimental plots?

L267: “Peponapis pruinosa” has recently been reclassified as “Eucera pruinosa” (see Dorchin et al. 2018). The new taxonomy should be reflected here and in Figure 2.

L284-286: You might consider including the study by Willis Chan & Raine (2021c) here alongside the other references as this work specifically shows impacts of pesticide applications to E. pruinosa in cucurbit growing systems.

L326-346: You discuss the importance of most of the wild bee genera in this section, but surprisingly do not discuss the importance of a cucurbit specialist pollinator – the hoary squash bee (Eucera pruinosa). In the methods you stated that “Pollinator visitation treatment observations occurred between 0900 and 1300 on days when the weather was sunny, mostly clear, and wind speeds below 2 m/s.” This likely means that you under-estimated the numbers of E. pruinosa visiting and pollinating watermelons as the females are actively foraging in other cucurbit crops shortly after dawn (e.g. squash pollination: Willis Chan & Raine 2021a).

References
Dorchin, A., M. M. López-Uribe, C. J. Praz, T. Griswold and B. N. Danforth (2018). Phylogeny, new generic-level classification, and historical biogeography of the Eucera complex (Hymenoptera: Apidae). Molecular Phylogenetics and Evolution 119: 81-92.

Garibaldi, L. A., I. Steffan-Dewenter, R. Winfree, M. A. Aizen, R. Bommarco, S. A. Cunningham, C. Kremen, L. G. Carvalheiro, L. D. Harder, O. Afik, I. Bartomeus, F. Benjamin, V. Boreux, D. Cariveau, N. P. Chacoff, J. H. Dudenhoffer, B. M. Freitas, J. Ghazoul, S. Greenleaf, J. Hipolito, A. Holzschuh, B. Howlett, R. Isaacs, S. K. Javorek, C. M. Kennedy, K. M. Krewenka, S. Krishnan, Y. Mandelik, M. M. Mayfield, I. Motzke, T. Munyuli, B. A. Nault, M. Otieno, J. Peterson, G. Pisanty, S. G. Potts, R. Rader, T. H. Ricketts, M. Rundlöf, C. L. Seymour, C. Schüepp, H. Szentgyörgyi, H. Taki, T. Tscharntke, C. H. Vergara, B. F. Viana, T. C. Wanger, C. Westphal, N. M. Williams and A. M. Klein (2013). Wild pollinators enhance fruit set of crops regardless of honey bee abundance. Science 339: 1608-1611.

Kremen, C., N. M. Williams and R. W. Thorp (2002). Crop pollination from native bees at risk from agricultural intensification. Proceedings of the National Academy of Sciences 99: 16812-16816.

Kremen, C., N. M. Williams, R. L. Bugg, J. P. Fay and R. W. Thorp (2004). The area requirements of an ecosystem service: crop pollination by native bee communities in California. Ecology Letters 7: 1109-1119.

McGrady, C. M., R. Troyer and S. J. Fleischer (2019). Wild bee visitation rates exceed pollination thresholds in commercial Cucurbita agroecosystems. Journal of Economic Entomology 113: 562–574.

Rundlöf, M., G. K. S. Andersson, R. Bommarco, I. Fries, V. Hederström, L. Herbertsson, O. Jonsson, B. K. Klatt, T. R. Pedersen, J. Yourstone and H. G. Smith (2015). Seed coating with a neonicotinoid insecticide negatively affects wild bees. Nature 521: 77–80.

Stanley, D. A., M. P. D. Garratt, J. B. Wickens, V. J. Wickens, S. G. Potts and N. E. Raine (2015). Neonicotinoid pesticide exposure impairs crop pollination services provided by bumblebees. Nature 528: 548-550.

WIllis Chan, D. S. and N. E. Raine (2021a). Hoary squash bees (Eucera pruinosa: Hymenoptera: Apidae) provide abundant and reliable pollination services to Cucurbita crops in Ontario (Canada). Environmental Entomology 50: 968–981.

WIllis Chan, D. S. and N. E. Raine (2021b). Phenological synchrony between the hoary squash bee (Eucera pruinosa) and culitvated acorn squash (Cucurbita pepo) flowering is imperfect at a northern site. Current Research in Insect Science 1: 100022.

Willis Chan, D. S. and N. E. Raine (2021c). Population decline in a ground-nesting solitary squash bee (Eucera pruinosa) following exposure to a neonicotinoid insecticide treated crop (Cucurbita pepo). Scientific Reports 11: 4241.