The mottled cup moth caterpillar, scientifically known as Doratifera vulnerans, is a fascinating Australian insect with a complex life cycle and a unique defense mechanism. These caterpillars are voracious feeders, primarily consuming eucalyptus foliage. Their venom has garnered scientific interest due to its potential medicinal and pest control applications.
Identification and Habitat
Doratifera vulnerans, also known as the Australian cup moth or Chinese Junk (referring to its caterpillar), belongs to the family Limacodidae. The species was first described by John Lewin in 1805 and is the type species of the genus Doratifera. These caterpillars are commonly found in eastern Australia.
The adult D. vulnerans moth is small with a rust-colored (ferruginous) body. The head region surrounding the antennae is white. It has two pairs of legs, and the two fore legs have white bands. The leg hairs, palpi, are white at the tip and brown at the base. The two fore wings are hairy with shiny rust color and silvery margins. Two hind wings are dull white with the edges slightly whitish. The main body is entirely light brown.
The caterpillars are only about 2 cm long. They are distinctively banded with different colours, considered as an evolutionary means of displaying its dangerousness (a phenomenon called aposematism). They are broad, thick, and short. There are four reddish and spiny projections on the anterior and posterior ends.
Diet and Feeding Habits
Cup moth caterpillars are Australian insects that feed on eucalyptus foliage. A single cup moth caterpillar can make short work of an entire eucalyptus leaf; a severe infestation can defoliate a tree. The tree generally recovers unless this happens several years in a row. Sometimes they also use other trees including guava and apricot.
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These voracious feeders can cause significant defoliation if present in large numbers. For people sharing the garden with the mottled cup moth, or related species, it helps to have some cup moth info handy in order to fight off these little buggers.
Venom and Defense Mechanism
The scientific name for the caterpillar, Doratifera vulnerans, means “bearer of gifts of wounds”. The caterpillar has clusters of sharp stinging spines that it displays when disturbed. It tucks away its spines when it doesn’t think it needs them, preserving the venom. If you just lightly brush up against one, you will get a very noticeable envenomation. The caterpillar’s spines inject liquid venom into anything that contacts it, resulting in a sharp or burning pain similar to a bee sting.
John Lewin discovered that the sting of these hairs are painful due to the presence of toxins and described this feature is a defence mechanism against predators. The caterpillars do not expose these spines unless they are stimulated or agitated by other animals. When the spines are in contact, the tips are easily broken thereby releasing the toxins, which can induce severely inflamed swellings. The general colour is grey studded with many dark spots and streaks.
The venom of a native Australian caterpillar contains compounds that could be used in medicines and pest control, new analysis has found. Caterpillars of the mottled cup moth have a complex venom made up of 151 separate toxins, according to new research published in the journal PNAS. The caterpillar’s venomous spines are thought to have evolved as a defence against predation by birds and other animals.
Composition and Potential Applications of the Venom
The venom is mostly peptides and shows stunning complexity, containing 151 different protein-based toxins from 59 different families. Researchers now know the amino acid sequences, or the blueprints, of each protein-based toxin. This will enable us to make the toxins and test them in diverse ways.
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Of particular interest among the 151 toxins identified, which were all made of peptides, was a compound called cecropin, which kills bacteria and parasites by disrupting their cell membranes. The scientists also found it was the main compound responsible for the pain the caterpillar’s venom elicits. Research is under way into whether the compound, which is also present in non-venomous caterpillars, could be used for its antimicrobial properties. Antimicrobial peptides of the Cecropin-family show potent antitumor activity against bladder cancer cells.
Another peptide present in the venom, known as DV33, was able to inhibit the growth of the barber’s pole worm, a common parasite found in sheep. The compound did not seem to have any adverse effects on the cells of mammals, so could potentially be used in agriculture. It has a molecular structure very similar to a lot of the spider venom peptides that we know are quite useful for treating diseases.
This research unlocks a new source of bioactive peptides that may have use in medicine, through an ability to influence biological processes and promote good health.
Life Cycle
Cup moths usually produce two generations of offspring per year. The adult moths are brownish in color and emerge from their rounded or cup-shaped cocoons in late winter or summer. They soon set to work mating and laying eggs, and the caterpillars hatch in spring and fall. The caterpillar is the only life stage that causes damage to plants.
D. vulnerans lays their eggs in clusters on leaves and cover them with their body hairs. The eggs are commonly found on Eucalyptus leaves.
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The colorful, slug-like caterpillars don't have legs like other caterpillars, so they glide across the surface of the leaf. The fleshy protuberances on both sides of the body look fearsome, but they are harmless. The danger comes from rosettes of retractable spines at the front and tail end of the body. Cup moth caterpillars can have up to four sets of spines.
By morning the chrysalis had hardened, shrunk to less than half the size and created this capsule that looks just like the gum nuts of the eucalypt trees the caterpillars feed on. Kim Sinclair has produced a great YouTube video of the whole process of cocoon formation by Doratifera vulnerans. We’ll have to wait till next spring to see the emergence of the adult moth from the cocoon. Collett and Fagg (ref. 2) state that in East Gippsland, pupae develop throughout winter and emerge as adults in September to recommence the lifecycle.
Managing Cup Moths in Gardens
For those living in Australia or other areas where the insect is found, gardening with cup moths can be both disconcerting and somewhat unpleasant. Protect yourself with gloves and long sleeves when working around cup moth caterpillars in the garden. Brushing against a caterpillar causes a painful sting, which later turns to intense itching. Though temporary, the effects of the sting are very unpleasant.
All types of cup moths are susceptible to viruses that help keep the insects in check. In addition, they have a number of natural enemies that include parasitic wasps and flies, as well as biting midges. Birds sometimes eat the caterpillars too. Because of these natural controls, treating the insects is often unnecessary. If natural solutions aren't enough, however, spray the caterpillars with Dipel. This insecticide, which contains Bacillus thuringiensis, an organism that causes the caterpillar to sicken and die, is rapidly broken down by sunlight, so spray on a cloudy day or at night. This insecticide is a good choice because it kills caterpillars without harming other wildlife.
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