Agriculture / Nature / Uncategorized

The Winter Rose and the Leaf Munchers

There’s always something to look at on the way to school. Even during the fall when trees are bare and creepy crawlies are still overwintering, I can manage to catch a glimpse of the odd winter flower. If anything, the lack of colour makes them more striking than the vivid fields of summer flowers. I always looked forward to seeing the Willamina Camellia (Camellia japonica cv. Willamina) bush beside my school’s football field during those cold months – the flowers are so pretty and plump, perfectly round and symmetrical.

The Willamina Camellia (Camellia japonica cv. Willamina) also reminds me of the tranquil environment of Yakushima’s Shiratani Unsuikyo. I went there two years ago and saw wild Japanese Camellias (Camellia japonica) for the first time. There were hardly any flowers in the moss covered forest during the winter so they naturally stole the spotlight.

Unfortunately, the Willamina Camellia (Camellia japonica cv. Willamina) flowers only bloom for a short time and I’ve been left with only waxy leaves for a long stretch of my walk. It’s usually the same green monochrome bush, but this made me do a double take yesterday:


Tea Tussock Moth larvae (Arna pseudoconspersa) feasting on a Japanese Camelia (Camelia japonicus) leaf  

I had never seen anything like it before. Weren’t caterpillars supposed to eat leaves like The Very Hungry Caterpillar? I thought there should only be one or two caterpillars munching on a leaf at any given time, creating cute, sparsely scattered polka dot holes. Not these caterpillars – with a legion on each side, they were devouring, literally, the entire leaf. Tea Tussock Moth (Arna pseudoconspersa) larvae are social caterpillars that feed in aggregate until their final instar. The reasons for such behaviour are survival driven: thermoregulation, shelter building, colony defines, and trail-based communication.


Tea Tussock Moth (Arna pseudoconspersa) feasting on a Japanese Camelia (Camelia japonicus) leaf

Unfortunately, the leaf munchers are so successful at feeding, they greatly impair the health of Japanese Camellias (Camellia japonica). Tea Tussock Moths (Arna pseudoconspersa) are considered a serious defoliator which decreases or eliminates a plant’s photosynthetic abilities. However, defoliator populations fluctuate with food availability and outbreaks will often be followed by periods of lower population. The most serious damage is often done by invasive species, where the normal boom-bust cycle does not apply: the Gypsy Moth (Lymatria disbar L.) has caused high incidence of tree mortality in North American forests, exacerbating ongoing declines in young oak classes in the region and driving long term changes in vegetation and species combination.

Although the Tea Tussock Moths (Arna pseudoconspersa) aren’t causing irreversible changes to natural forests, they are decreasing the output of Japanese Camellia (Camellia japonica) farms. As such, humans have intervened and farmers are resorting to pheromone traps, that lure adults and prevent mating, to prevent outbreaks.

Do you think there will be unintended consequences of these pheromone traps?


















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