|Title:||亞麻夜蛾(Heliothis zea Boddie)之生態研究||Other Titles:||Ecological Studies no Heliothis Zea (Boddie)||Authors:||杜金池
|Issue Date:||Sep-1965||Publisher:||植病保護學會||Journal Volume:||7||Journal Issue:||3||Start page/Pages:||114-125||Source:||植物保護學會會刊||Abstract:||
The bollwcirm, Heliothis Zea (Boddie) has long been recognized of its damage to flax crop. The caterpillars of this insect prefer to feed on leaves, top-seedlings and the fruiting parts of plants. It not only weakens the hosts but also induces the later to ramify, and thus the fiber quality is degraded and the production of flax fibers is decreased. Even the collection of seeds may become a serious problem after being attacked by this insect.
Besides thigmotropism, chemotropism, negative phototropism, the larva also has the habit of cannibalism to kill and eat its own kind, especially after the third instar. There are one to six generations of the insect annually, the numbers depending on the latitude, here in Taiwan 6 generations have been observed. The duration of one generation varies under different conditions, the shortest takes 21 days at 33 ±2℃. Hibernation of this insect has not been found in Taiwan. The insect abundantly occurs in mid-January during the growth season of flax.
The longevity of the imago is related to temperatures, humidities, foods and sexes, and generally the female has a longer longevity than the male. At room temperature in winter, the longevity of the female is 22±7 days and the male 11±3 days. The female deposits eggs singly at the top leaves of flaxes, the farther from the top parts of the plant, the less the eggs were laid. Each female can lay about 1,200 eggs within 11 to 25 days. In general, the female appears more plenty than the males. The egg period is also not even under different conditions of temperature, humidities. Within appropriate temperatures, the egg period is shortened with the raise of temperature. In winter, incubation period takes 8 to 15 days at room temperature (Avegage, 21.4℃.), and 2 to 7 days at 24±1 C.
The larva moults 5 times and has 6 instars, its duration differs with temperatures, humidities, food and circumstances. The larval period takes 23 to 26 days at 21º± 4℃. and 17 to 23 days at 23±2℃. Under 30℃ condition, the larva acts violently, eats very much and developes quickly; above 40℃, no feeding and no survivals existed. While under condition below 20℃, its activity and development become slowly; below 11℃ no completion of larval development was observed. The skin moulted is always eaten by the larva and only the skull is left which can be used for the identification of moultings.
In the farm, the insect passes the winter in the form of a brown pupa. On becoming full-grown the larvae crowl down the stalk or drop to the ground, into which they borrow and excavate a small smooth-walled cell commonly 3.5 to 13 cm. deep, where they pupate, then coming out as moth after period of 37 to 42 days at 21.4℃ and soil humidity of 20% in winter; and 8 to 30 days under 25℃. The pupal period also differs with the different temperatures, soil humidities and foods the larvae fed. It may be prolonged during cold weather and shortened during hot weather.
|Appears in Collections:||植物病理組|
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