Garden tiger moth

Species of moth

The garden tiger moth or great tiger moth (Arctia caja) is a moth of the family Erebidae. Arctia caja is a northern species found in the US, Canada, and Europe. The garden tiger moth is found throughout much of the Palearctic, in Europe as far north as Lapland, in Northern Asia and Central Asia, and in North America. In the mountains (Tien Shan), this species is found up to an elevation of .

This species prefers numerous types of wild habitat, from grasslands to forests. Because of its generalist diet, it is not constrained by features such as host plant location. The only constant quality of a habitat for these animals is that it must be seasonal and cool, and like many members of Genus Arctia, tropical climates do not suit garden tiger moth larvae or adults.

The larvae of A. caja are generalists, meaning they eat a large variety of plants without much specialization. However, most larvae of this species obtain their characteristic toxic compounds from their diet, which can vary from foxglove (and members of the daisy family)

Because of A. caja’s generalist diet while in the larval stage, it is subject to a wide variety of plant defenses. One study tested plant health with and without beneficial fungus known as Arbuscular mycorrhiza (AM), and saw that Plantago lanceolata with beneficial fungus produce more anti herbivore toxins, which negatively influenced caterpillar growth. The beneficial fungus gained sugars from the plant, while the plant gained soil nutrients from the fungus, such as phosphorus and nitrogen. Due to the plant fungus symbiosis, plants were able to produce more toxins than normal due to the fungus’ acquisition of additional usable resources from the soil, and in turn harm the larvae's consumption of leaf matter. The effectiveness of this plant response was tested on several species of Lepidoptera. The larvae depend upon the host plant for their toxic compounds,

While not often eaten due to its toxicity, naïve birds will on rare occasion consume either the adult or larval stages of this species. These sounds have been found to affect bat behavior, as the squeaks of this insect cause bats to avoid the noxious moth. Bats that could associate squeaking or clicking sounds as indicative of toxic prey quickly used sound alone as a deterrent.

The digestion of this species is most remarkable in the larval stage. The host plants of this species almost always carry toxins known as pyrrolizidine alkaloids. Its numbers in the UK have declined by 89% over the past 30 years. The BAP in 2007 added the garden tiger moth to its list of species in need of habitat protection in light of these recent declines in suitable habitat. The plan aims to provide greater habitat protection and conservation, with the hopes of stabilizing the A. caja populations that remain in the UK.

The garden tiger moth population decline is of concern for both laboratory research and in nature. A possible way to combat this in a laboratory setting is to use synthetic food. While not ideal, it resolves many issues that arise when trying to raise captive Lepidoptera. Concerns such as food sterility are quickly resolved, along with issues of gathering hard to find or cultivate host plant material. Many larvae, including those of A. caja, can consume synthetic food, which is based primarily on agar, powdered cellulose, cabbage, sucrose, salts, and wheat germ. Synthetic options appear to be a promising way to raise lab populations of this species, for conservation or for study.