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written by: Jillian Stewart Entomology has a new downstairs neighbor in the Plant Sciences Department! He’s an invasive species ecologist, but don’t worry, he’s here to collaborate. Dr. Dan Buonaiuto studies how climate change affects biodiversity and the functions of plant communities with a particular focus on phenology. Phenology is the timing of lifecycle events in an organism’s life: when it emerges from dormancy, when it molts, when it mates, and what factors influence this timing. How is climate change influencing plant phenology? Plants rely on temperature cues and light periods to determine when they flower, leaf out, and go dormant (Buonaiuto et al, 2023). In many plants, the sequence of flowering and leafing in the spring is very important to their reproductive success. Some plants leaf first, others flower first. Many plants produce hermaphroditic flowers -each flower has male and female gametes. Other plants are monoecious, where the male and female flowers are separate but still on one plant. Some plants produce their male flowers first, others produce the female flower. This temporal separation of male and female is called dichogamy and can be a delicate balance! Leafing, male flowering, and female flowering can all have different phenological sensitivities to climate change (figure one). This can make reproduction in monoecious plants particularly vulnerable to warming. Many monoecious plants cannot self-fertilize. If their male and female flowers overlap too much, the female flowers may become clogged with pollen from the same tree. This can reduce the reproductive output of a tree or, if the pollen is usable, reduce the genetic diversity of offspring. Reduced genetic diversity can impede a species’ ability to adapt to changing conditions like climate change (Buonaiuto, 2024).  Figure One) Change or lack thereof in separation of male and female flowers on dichogamous trees. In a & d, both change at the same rate. In b & f, the gap between male and female flowers closes. In c & e, the gap widens (Gong et al, 2025). Dr. Buonaiuto and his lab searched through prior work by naturalists to identify trees that flowered first (male or female) or leafed first and by how many days these events were separated (figure two). Wind-pollinated trees tended to flower first due to better airflow before the leaves grow in. They discovered that when it got warmer, leaves emerged sooner in the year. Flowering did not move forward at the same rate, narrowing the window in which flowers were alone on the trees. But some animal-pollinated trees also flower before leafing. Why? There are two standing theories in the scientific community. First, leafing and flowering at different times may reduce water loss by evapotranspiration. This is because the tree has less surface area exposed at any one time, helping it conserve water. Second, flowering first may enhance visibility to pollinators. Without leaves in the way, it is easier to recruit pollinators to the flowers. The tree does not have to invest as many resources into making its flowers large and attractive to draw in pollinators. During the COVID quarantine, Dr. Buonaiuto worked to test these hypotheses using the genus Prunus which has members that flower first and others that leaf first (Buonaiuto et al, 2020) These two hypotheses are not mutually exclusive. However, Dr. Buinaiuto raised the question of why a tree would need to be drought tolerant in the spring as this region is not prone to spring droughts -anymore. A few thousand years ago, the Southeast of modern-day America suffered regular springtime droughts. Today’s plants are still adapted to those conditions. In modern-day America, Dr. Buonaiuto found that species with a history of drought were more likely to flower first. Inflorescence size (the whole body of the flower) tended to be larger in plants that leafed first, but the relationship was less clear.  Figure Two) Some trees flower before leafing, others leaf before flowering (Buonaiuto et al, 2021). Plants are not the only organisms that need to adapt to climate change. The organisms that we use to control pests, and the pests themselves, are also subject to rising temperatures and changing climatic conditions. Dr. Buonaiuto, with the Regional Invasive Species and Climate Change (RISCC) management network, are investigating the role climate change plays in biocontrol success and invasive species spread. High temperatures can outright kill insects, or harm their ability to hunt and reproduce. High temperatures can also enhance overwintering survival, increase the number of generations per year, and expand habitable ranges towards the poles. Successful pest species tend to be more robust than predators and parasitoids we employ to control them. If a pest species does better, or just breaks even under high temperatures, and their natural enemies suffer, then biocontrol efficacy will decrease. Dr. Buonaiuto and RISCC colleges performed a literature review of existing research on biocontrol agents, their pests, and climate change (Evans et al, 2025). While there was plenty of research on these topics individually, few studies combined them. Of those, only 18 studied the biocontrol agent and its pest at the same time. Most of these studies found no change in the fitness of either species. Only a couple found that one or the other declined and the other was unaffected.
Of course, this is a small sampling of the many organisms we use as biocontrol. Each species may react differently to climate change, and factors other than temperature also play a role. Dr. Buonaiuto and RISCC are looking for collaborators interested in insects to join them in studying biocontrol agents and invasive species. He is also continuing his research on phenology shifts in trees’ leafing and flowering sequences. https://www.risccnetwork.org/ Daniel M. Buonaiuto, Megan J. Donahue, E. M. Wolkovich. (2023), Experimental designs for testing the interactive effects of temperature and light in ecology: The problem of periodicity. British Ecological Society, vol. 37 issue 6. https://doi.org/10.1111/1365-2435.14329 D. M. Buonaiuto. (2024), How Climate Change May Impact Plant Reproduction and Fitness by Altering the Temporal Separation of Male and Female Flowering. . Global Change Biology, Vol 30 Issue 10. https://doi.org/10.1111/gcb.17533 Buonaiuto, D.M., Morales-Castilla, I. and Wolkovich, E.M. (2021), Reconciling competing hypotheses regarding flower–leaf sequences in temperate forests for fundamental and global change biology. New Phytol, 229: 1206-1214. https://doi.org/10.1111/nph.16848 Evans, Annette E., William G. Pfadenhauer, D. M. Buonaiuto, Matthew E. Fertakos, Carrie J. Brown-Lima, and Toni Lyn Morelli. (2025),The Future of Biocontrol in the Anthropocene: A Review of Climate Change Impacts on Biocontrol Agents and Their Targets. Ecological Applications 35(6): e70088. https://doi.org/10.1002/eap.70088 Wu, Z., Gong, Y., Zohner, C.M., Vitasse, Y., Li, M., Nie, Y., Buonaiuto, D.M., Morellato, L.P.C., Guo, Z., Wang, S., Wang, N., Wang, H. and Fu, Y.H. (2025), Stabilizing mechanisms enable dioecious trees to maintain synchrony in spring budburst under climate warming. New Phytol, 247: 1655-1665. https://doi.org/10.1111/nph.70290 Comments are closed.
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