Whiteflies: are they to blame for my non-flowering, Night Blooming Jasmine?
Oct 30, 2020 • 3:13 PM UTC
Kailua, HI 96734, USA
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omeyers
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“Smell the flowers” by Jerry Reed
I conducted this project as part of Professor Pringle’s EEB321 class at Princeton University. Walking around my yard in Kailua, Oahu, I was struck by the beautiful assemblage of flowering plants. Yet, my eye was drawn to the one plant that didn’t seem to have any flowers. After researching and asking my renter, I identified the plant as a night blooming jasmine (Fig. A, 50% sure this is right), which is a common ornamental plant in Hawaii. Its flowers open at night, and emit an apparently wonderful odor between July and October. I’ve been gypped from smelling these flowers (unless I have gotten the species wrong) because my plant has none, and only a few buds.
Interestingly, there were dense clumps of cotton-like dots on the back-side of many of its leaves, that were not present on the other flowering plants (Fig. B). At first, I thought it was fungus, and wondered if this plant pathogen was perhaps drawing away resources from the plant, and stunting both the production and flowering of buds. I took out my foldoscope to see what type of herbivore this plant was up against. Upon closer look, I noticed a white fly (Fig. C).
I conducted this project as part of Professor Pringle’s EEB321 class at Princeton University. Walking around my yard in Kailua, Oahu, I was struck by the beautiful assemblage of flowering plants. Yet, my eye was drawn to the one plant that didn’t seem to have any flowers. After researching and asking my renter, I identified the plant as a night blooming jasmine (Fig. A, 50% sure this is right), which is a common ornamental plant in Hawaii. Its flowers open at night, and emit an apparently wonderful odor between July and October. I’ve been gypped from smelling these flowers (unless I have gotten the species wrong) because my plant has none, and only a few buds.
Interestingly, there were dense clumps of cotton-like dots on the back-side of many of its leaves, that were not present on the other flowering plants (Fig. B). At first, I thought it was fungus, and wondered if this plant pathogen was perhaps drawing away resources from the plant, and stunting both the production and flowering of buds. I took out my foldoscope to see what type of herbivore this plant was up against. Upon closer look, I noticed a white fly (Fig. C).
Fig A: Night Blooming Jasmine ( Cestrum nocturnum )
Fig B: Cotton-like tufts on backside of the leaves
Fig C: Can you see the white fly? I captured it, stuck it on a slide, and investigated. It turned out to be a greenhouse whitefly (found below), which is a common pest of this ornamental plant. Whiteflies are sap feeders, tapping into the phloem of plants and excreting a honeydoo substance that allows mold to grow on the leaves (which I didn’t see on my plant). While whiteflies do seem to have a negative impact on this jasmine plant, I don’t think it is causing the stunted bud growth and lack of flowering. Perhaps other pests of the night blooming jasmine plant (like ants, which I noticed crawling on the leaves) are the real culprit preventing me from enjoying the smell of these flowers! For now, though, whiteflies seem to be in the clear.
I satisfied my curiosity by finally investigating the small white clumps, which I hypothesized were the larvae of the whiteflies. One of the scale-like dots I chose did resemble the nymph stage of a whitefly (Fig. E). But, the foldoscope images of the cotton-like clumps with dark dots in the middle were hard to distinguish and did not match any life-cycle stage (Fig. F). Are these white clumps a separate pathogen/pest on this plant, or are they part of the whitefly life-cycle? Many questions remain. I am sure more than whiteflies, though, are exploiting this jasmine plant.
Fig. E: Lymph scale
Fig. F: Cotton clump with black dot
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