Answer: You're right that there aren't as many pollinators around, for a variety of reasons. A mite has devastated the honey bee population, and the media has scared everyone with "killer bees" so people are having hives removed in greater numbers than before. You might try a diverse planting of flowers to encourage more visitors. Some annuals that do well in the heat are coreopsis, cosmos, gaillardia, vinca, lisianthus, and salvia. Herb flowers are also great for attracting insects. Limiting or eliminating pesticide use also encourages them.
Most vining crops start by producing a lot of male flowers before the females, and these early flowers wither and die. Once both flowers are present, you can hand pollinate the blossoms yourself by taking a small artist's paintbrush or cotton swab and transferring pollen from the male flower(without a small fruit behind the flower) to the female flower (the one with a small fruit behind the flower).
Tomato pollen isn't viable much over 90 degrees, so fruits won't set when temperatures get too high. You can try gently tapping and shaking tomato plants in the early morning to help pollination occur.
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