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AGE DEPENDENT CHARACTERISTICS OF 1-2 AGE LARVAE OF
TURNIP MOTH (AGROTIS SEGETUM DENIS &
SCHIFFERMÜLLER,1775)
A.Yoqubov
researcher, Fergana State University
https://doi.org/10.5281/zenodo.11201243
Annotation.
Age-related characteristics of 1-year-old larvae of turnip
moth were studied. The changes that occur in the div parts of the worm after
hatching and until the end of the 1st year or the time of hatching are described.
A number of scientists have given descriptions of the stages of
development and different ages of the worms of the autumn nightshade, and the
main attention has been given to the classification of the worms according to
such characters as div color, head and div size. However, the detailed
description of the location of the spots on the back of the autumn moth
caterpillar, taking into account the fact that it is typical not only for the autumn
caterpillar, but also for the larvae of some other species of butterflies, it is
recognized that it is difficult to determine the distribution ratio of most
caterpillars in nature according to the given characters, and reported the
importance of head capsule measurements to determine the age of autumn
caterpillars[1,3].
Detailed descriptions of the larval stage of the autumn moth are known
from some studies, and these studies focus not only on the features specific to
the larvae of the autumn moth, but also on the differentiation of the characters
of the autumn and exclamation moths [2].
In some scientific sources, the ecology of larvae of all ages of the autumn
caterpillar is covered in detail, but little attention is paid to the size of worms
depending on age [4].
In the conditions of the Fergana region, researches related to the
distribution and pest characteristics of the autumn caterpillar were conducted,
and no information was recorded on the age-related characteristics of the
worms [5,6].
Differences in the larval stage of the autumn nightshade by young people
are not sufficiently substantiated by numbers. The color and size of the div in
such cases show a wide variety, so we focused on the signs that do not change
during life. As such a sign, importance was attached to qualitative and
quantitative changes occurring in the div length of the worm at the time of
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hatching and the width of the head capsule, which does not always change in
size.
The 1st instar of worms begins with the process of breaking the egg shell.
By gnawing on the eggshell, it makes a hole below the top of the egg (rarely
above the top of the egg) and slowly expands it.
It feeds by swallowing gnawed parts. After hatching, the worms feed on
the soft part of the leaves in the case of a plant, or they can gnaw it and make
small holes. If the worm has hatched in a non-plant (soil) or dry plant, it can
move to other places or climb plants. But as a result of underdeveloped
abdominal legs and growths on them, worms cannot stand firmly on plants or
other places.
The color of the head of the worm that hatched from the egg is black and
has a shiny appearance. The head is divided into three parts, two of which are
convex on the sides, and the third reaches from the base to the upper lip, in the
form of a triangle, and the apex reaches the border of the head with the first
thoracic segment. . The front part of the head has a pair of tentacles ending in
short spines. The upper jaw of the worm is dark-brown in color.
Head capsule width 0,33+0,001mm. The color of the worm when it
hatches is yellowish-gray, after feeding, it turns gray-green due to the visibility
of the intestine through the chitin coating. On the first thoracic segment of the
div, a back neck shield appears, almost the same color as the head. The last
abdominal segment has a second shield of the same color. The whole div of the
worm is made up of 11 clearly distinguishable segments, and the back is covered
with black dots.
From each of the points comes a long brown blade, ending in a knob-like
thickening. The color of the sword, thickened like a club, is liquid, and the tip of
the sword looks like a small drop of water. Similar spines are present on the
head of the worm and on both shields. The worm's div is naked from below.
Beneath each of the three segments is a pair of true legs, each ending in a sharp,
light-brown claw.
The first, second and third abdominal segments do not have legs. On the
fourth segment is the inconspicuous base of a pair of abdominal legs, and on the
fifth and sixth segments there is a pair of well-defined false legs. The seventh
and eighth segments are similarly devoid of legs, and the last, ninth segment has
a third distinct set of abdominal legs. On both sides of the worm's div there are
nine pairs of respiratory holes in the form of round holes with a dark brown
circular border, these holes are surrounded by black plate-like dots. Air vents
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are located on the first thoracic and 1-8 abdominal segments, the first and last
pairs are much larger than the others.
When the ratio of the length of the div of the 1st year worm to the width
of the head capsule ("A" index) is determined using the Kosobutsky formula
(A=P/Q where P is the length of the worm div and Q is the width of the head
capsule), the A-index is 9.37± It was found to be equal to 0.17.
The width of the head capsule of the second instar worm is 0.62±0.0012
mm. The head of the worm turns white after molting at the end of the first instar.
Later, the color of the head becomes darker. It is lighter in color compared to the
color of the head capsule in the first-year belts. At the head of the worm, two
triangles with the ends pointing in different directions are intended. One of
these is larger in size, and its base is directed towards the upper lip, and the base
of the other is directed towards the chest segment. In fact, the second triangle is
formed as a result of a fold on the side of the head, and this fold cuts out a small
triangular area that fits into the central recess of the head.
This triangular area may not be present when the worm's div is
extremely elongated before hatching. Later, the div of the worm becomes
striped, and the color of the div becomes brownish-gray. The striped
appearance is caused by an odd number of oozing stripes down the middle of
the div, with two darker, brownish stripes alternating with two oozing stripes
on either side. The tufted thickenings of the hair tend to stretch along the length,
so the tufted look is less exaggerated. The pair of false legs in the fourth
abdominal segment is better expressed than in the first age; in addition, in the
third abdominal segment there is an incomplete base of the last eighth pair of
legs. The heel of the false legs of the second instar worm is more clearly defined,
and the third pair of false legs now has 5-6 claws, and the fourth pair has 7-8
claws. When the worm feeds on the leaves of various plants, it completely
pierces them, and in some cases it can even gnaw at the edges.
The ratio of the length of the div of the worm of the second age to the width of
the head capsule ("A" index) was found to be equal to 8.56 ± 0.17.
References:
1. Россиков К.Н., “Озимая совка, ее жизнь, свойства и меры борбы”. Издания
Департамента Земледелия, Санкт – Петербург, 1909г.
2. Дехтярев Н.С., “К сравнительной морфологии неполовозрелых стадий
Euxoa segetum Sch. и Feltia exclamationis L” “Захист Рослин”, Ч.5-6. Грудень,
1925 року.
3. Плотников В.И., “Насекомые, вредящие хозяйственным растениям в
Средней Азии”. Издания Н.К.З. Узостазра. Ташкент, 1926г.
SCIENCE AND INNOVATION IN THE
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4.Остапец А.П., “Биология озимой совки в условиях Воронежской
губернии”. “Бюллеттень Воронежск.Стазра”. Выпуск VII, 1926г.
5. Zokirov I.I. Markaziy Farg‘onaning sabzavot-poliz ekinlari hasharotlari faunasi
va ekologiyasi: Biol. fan. dokt. (DSc) ...diss. avtoref. – Toshkent, 2019. - 59 b.
6.Yoqubov A.A., Mahmudov M.U. Kuzgi tunlam (Agrotis segetum Denis&Schiff)
ning biologik xususiyatlari haqida// “Ilm-zakovatimiz – senga, ona-Vatan!”
mavzusidagi Respublika onlayn ilmiy-amaliy anjuman materiallari, -Fargʻona,
2022. 81- 82b.
