Potato Tuber Moth

Potato tuber moth, (Phthorimaea operculella )
Identification
The adult potato tuber moth has a narrow silver-grey body and greyish-brown wings patterned with small, dark specks. The body length is about 10 mm and the wingspan is about 12 mm. The moths are active mainly at dusk, but during the day can be seen flying sporadically within potato crops.
The oval eggs are laid singly on the underside of potato leaves and on exposed tubers. When first laid they are pearly white, changing to yellow on maturity and to black just before hatching.
The larva [caterpillar] on hatching is 1-2 mm long and grows through four instars [stages] to reach a length of 15-20 mm. Young larvae are grey or yellow-white; mature, healthy larvae are tinged with pink or green. All instars have a dark brown head.
Pupae are formed in a silken cocoon covered with soil particles and debris for camouflage. Pupation [change from a larva to a pupa] occurs among dead potato leaves, on the soil, or on stored potato tubers.

Host plants
Potato tuber moth is a major pest of potatoes in New Zealand. The range of hosts is limited to the family Solanaceae. The most commonly attacked plants of economic importance are potato, tobacco, egg plant, and, occasionally, tamarillo leaves. The native weed poroporo may be heavily attacked.

Damage
Both foliage and tubers suffer extensive damage. This is caused by the larvae, which normally spend their entire lives in either one of these food sources; the only exception to this is when infested foliage is destroyed, forcing larvae to abandon it and search for tubers. Foliage-mining larvae create transparent leaf blisters and may also mine the petioles [leaf stalks]. Foliar infestation may be sufficiently severe to destroy the plant. Tuber-mining larvae usually enter through the "eyes" from eggs laid nearby, and make slender, dirty-looking tunnels throughout the tuber. An infested tuber can be identified by mounds of frass [droppings] at the tunnel entrances. High levels of tuber infestation occur in the field during summer, and stored potatoes can suffer severe damage all the year round.
Distribution
Potato tuber moth is cosmopolitan [world-wide in distribution]. In New Zealand it occurs throughout the potato-growing areas of the North and South islands, and thrives best in areas with hot dry summers.

Life cycle
Egg
Larvae
Pupae
Adult
Month
Note: Coloured bars indicate periods of peak activity in each of the life cycle stages
As many as 6-8 generations may occur in the field during summer. As a result generations are not distinct, and between December and April every stage of the life cycle may be present in abundance. In mid summer a complete generation spans 4-5 weeks: eggs hatch in 2-6 days, larvae mature in 16-24 days, pupae hatch after 6-9 days, and adult females begin to lay eggs after 2-4 days. As the temperature drops m autumn the population declines, and the duration of the life cycle gradually lengthens until in winter it spans 20-24 weeks. By August-October the overwintering population consists almost entirely of pupae. These hatch in November with the onset of warm, dry conditions, to begin the next summer population explosion. In stored potatoes the population continues to breed all the year round, the length of the life cycle depending on storage temperature.

Colorado potato beetle

Colorado potato beetle

The Colorado potato beetle (Leptinotarsa decemlineata, also known as the Colorado beetle, ten-striped spearman, the ten-lined potato beetle) is an important pest of potato crops. It is approximately 10 mm (0.4 inches) long, with a bright yellow/orange body and 5 bold brown stripes along the length of each of its elytra, and it can easily be confused with its close cousin and look-alike, the false potato beetle. The beetle was described in 1824 by Thomas Say from specimens collected in the Rocky Mountains on buffalo-bur, Solanum rostratum. The origin of the beetle is somewhat unclear, but it seems to be that Colorado and Mexico are a part of its native distribution in the south-western part of North-America.
Contents
1 Life cycle
2 As a crop pest
3 In Europe
4 Philately
5 References
6 External links
Life cycle

Colorado potato beetle larvae
Colorado potato beetles (CPB) fed originally on the leaves of buffalo-bur, but when domesticated potatoes were introduced into the beetles' native range, the beetles shifted to potatoes. CPB also occasionally attack tomatoes and eggplants. CPB females are very prolific; they can lay as many as 800 eggs. The eggs are yellow to orange, and are about 1.5 mm long. They are usually deposited in batches of about 30 on the underside of host leaves. Development of all life stages depends on temperature. After 4-15 days, the eggs hatch into reddish-brown larvae with humped backs and two rows of dark brown spots on either side. They feed on the leaves. Larvae progress through four distinct growth stages (instars). First instars are about 1.5 mm long; the fourth is about 8 mm long. The larvae in the accompanying picture are third instars. The first through third instars each last about 2-3 days; the fourth, 4-7 days. Upon reaching full size, each fourth instar spends an additional several days as a non-feeding prepupa, which can be recognized by its inactivity and lighter coloration. The prepupae drop to the soil and burrow to a depth of several inches, then pupate. Depending on temperature, light-regime and host quality, the adults may emerge in a few weeks to continue the life cycle, or enter diapause and delay emergence until spring. They then return to their host plant to mate and feed. In some locations, 3 or more generations may occur each growing season.
As a crop pest
The Colorado beetle is a serious crop pest of potatoes. Insecticides are often unsuccessful when used against Leptinotarsa because of the beetle's resistance to toxins and ability to rapidly develop resistance to them. The Colorado beetle has developed resistance to all major insecticide classes. In the United Kingdom, where the Colorado beetle is a rare visitor on imported farm produce, it is a notifiable pest: any found must be reported to DEFRA.

In Europe
Native ranges of the Colorado beetle and the potato
In 1877, the Colorado beetle reached Germany where it was eradicated. During, or immediately following WWI it became established near USA military bases in Bordeaux and proceeded to spread by the beginning of WWII to Belgium, the Netherlands and Spain. The population increased dramatically during and immediately following WWII and it spread eastwards and it is now found over much of the continent. During World War II, the Nazi regime in Germany used them for propaganda, claiming that the beetles had been dropped by the United States Army Air Forces. The Americans were also blamed by regime propaganda when after World War II, in the Soviet occupation zone of Germany, almost half of all potato fields were infested by the beetle by 1950. In the EU it remains a regulated (quarantine) pest for the UK, Republic of Ireland, Balearic Islands, Cyprus, Malta and southern parts of Sweden and Finland. It is not present in any of these Member States.