FURTHER STUDIES ON THE BIOLOGY OF PYRRHARCTIA (ISIA) ISABELLA (LEPIDOPTERA: ARCTIIDAE): III. THE RELATION BETWEEN HEAD CAPSULE WIDTH AND NUMBER OF INSTARS

1979 ◽  
Vol 111 (3) ◽  
pp. 323-326 ◽  
Author(s):  
Mark S. Goettel ◽  
Bernard J. R. Philogène
Keyword(s):  
Inverse Relationship ◽  
Head Capsule ◽  
Larval Instars ◽  
Head Capsule Width ◽  
Mature Field ◽  
Average Size

AbstractHead capsule widths of laboratory-reared and mature field-collected larvae of P. isabella were measured. The number of larval instars varied from 7 to 10, yet in all larvae studied, average size and increment in the successive instars were the same for instars 1 to 3. In the latter instars, there was an inverse relationship between size of increment and prospective number of instars. Insects which completed 10 instars were only a little larger than those maturing after only 7 instars. These data fail to support Dyar’s rule.

LARVAL GROWTH AND DEVELOPMENT OF ARGIA VIVIDA (ODONATA: COENAGRIONIDAE) IN WARM SULPHUR POOLS AT BANFF, ALBERTA

1977 ◽  
Vol 109 (12) ◽  
pp. 1563-1570 ◽  
Author(s):  
Gordon Pritchard ◽  
Brian Pelchat
Keyword(s):  
Life Cycle ◽  
Rapid Growth ◽  
Growth And Development ◽  
Larval Growth ◽  
Head Capsule ◽  
Temperature Dependent ◽  
Vernal Equinox ◽  
Larval Instars ◽  
Head Capsule Width ◽  
Major Shift

AbstractSamples of a population of Argia vivida Hagen larvae were taken at about monthly intervals from a series of warm sulphur pools at Banff, Alberta, from June 1973 to December 1974. Changes in head capsule width and wing pad length in field-collected and laboratory-reared specimens show that the life-cycle is univoltine. Only the final (Z) instar can be recognized with certainty, but methods are described whereby the population can be divided into size classes which are thought to correspond well with the last nine larval instars. Periods of rapid growth occur in the autumn and again in the spring. Larvae overwinter in the instars U, V, W, X, and Y and the major shift to the final instar occurs in March and April. Adults emerge from April to August. In the laboratory, growth is temperature dependent until the penultimate (Y) instar and this could be a factor in the field since, although larvae can exist year-round at a constant 26 °C, some larvae live in the cooler areas at the edges of the streams and pools. Entry to the final instar appears to require the long photoperiods that follow the vernal equinox.

scholarly journals Development and determination of larval stages of fall armyworm on some staple crops

1970 ◽  
Vol 29 (4) ◽  
pp. 445-457
Author(s):  
O.O. Odeyemi ◽  
O.T. Alamu ◽  
G.A. Yekinni ◽  
Q.O. Oloyede-Kamiyo
Keyword(s):  
Larval Development ◽  
Fall Armyworm ◽  
Head Capsule ◽  
Sub Saharan Africa ◽  
Pupal Weight ◽  
Alternative Host ◽  
Growth Ratio ◽  
Larval Instars ◽  
Head Capsule Width ◽  
Mean Width

Fall armyworm (FAW), Spodoptera frugiperda Smith (Lepidoptera: Noctuidae), is a serious emerging pest of maize (Zea mays L.) and many other alternative crop hosts in sub-Saharan Africa. Adequate knowledge on the development of S. frugiperda on maize and other alternative host crops is important in the development of integrated pest management programmes. The objective of this study was to determine the larval developmental stages of FAW using head capsule and other body morphometrics of FAW on maize and other alternative host crops in Nigeria. Food hosts (maize, cassava and cowpea) were replicated five times and arranged in a Completely Randomised Design. The results showed that mean growth ratio of larval development on maize, cassava and cowpea were 1.51, 1.54 and 1.50, respectively; and all conformed to Dyar’s rule. Head capsule width of larval instars showed six frequency peaks, representing six larval instars. Mean width of head capsule from the first to sixth larval, in the three crops, were significantly different. The shortest (14 days) and longest (17 days) developmental periods were recorded on maize and cassava. Pupal weight and length were not significantly different among the crops. There was a linear and significant correlation (maize = 0.98, cassava = 0.98 and cowpea = 0.99) between the stages of larval development and head capsule width. The number of larval instars of FAW, duration of their developments and the weights of larva and pupa on maize, cassava and cowpea are useful information in determining the number of generations of FAW on each crop. This information could, therefore, be applied in decision making on the appropriate time and duration of application of control actions when these crops are infested.

scholarly journals Determination of Helicoverpa armigera (Lepidoptera: Noctuidae) larval instars and age based on head capsule width and larval weight

2017 ◽  
Vol 15 ◽  
pp. 53 ◽  
Author(s):  
D. G. Stavridis ◽  
C. G. Ipsilandis ◽  
P. C. Katarachias ◽  
P. G. Milonas ◽  
A. A. Ifoulis ◽  
...  
Keyword(s):  
Body Weight ◽  
Helicoverpa Armigera ◽  
Larval Instar ◽  
Head Capsule ◽  
Head Width ◽  
Larval Instars ◽  
Head Capsule Width ◽  
Helicoverpa Armígera ◽  
L1 And L2 ◽  
Lepidoptera Noctuidae

Larνae of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) were reared in laboratory conditions (26°C, 16:8 L:D) and measurements of larval head capsule width, and body weight, were used in order to determine the boundaries of larval instars. Larvae of Η. armigera completed development in 5 to 7 instars. Head capsule width could predict the larval instar only for Ll. The upper boundary of head width for L1 was 0.4mm. Body weight could predict both L1 and L2 larval instars. Boundaries between L1-L2 instars were found to be 1 mg and for L2-L3 5,5 mg. Correlation and regression analysis suggest that a combination of head capsule width and body weight can predict both larval instars and chronological age under constant conditions in the laboratory.

INSTAR DIFFERENTIATION IN LARVAL CHIRONOMIDAE (DIPTERA)

1974 ◽  
Vol 106 (2) ◽  
pp. 179-200 ◽  
Author(s):  
Victor J. E. McCauley
Keyword(s):  
British Columbia ◽  
Head Capsule ◽  
Larval Instars ◽  
Head Capsule Width

AbstractExamination of the most commonly used criteria for separating instars in larval chironomids, based on a study of 29 species from three subfamilies in Marion Lake, British Columbia, revealed that only head capsule width or length is suitable. Most chironomids appear to have four larval instars.

Morphology of the immature stages of Meligethes aeneus (F.) and M. viridescens (F.) (Coleoptera, Nitidulidae)

1965 ◽  
Vol 55 (4) ◽  
pp. 747-759 ◽  
Author(s):  
P. Osborne
Keyword(s):  
Experimental Evidence ◽  
Head Capsule ◽  
Immature Stages ◽  
Meligethes Aeneus ◽  
Larval Instars ◽  
Head Capsule Width ◽  
Laboratory Conditions ◽  
First Time

Experimental evidence is given to show that only two larval instars occur during the development of Meligethes aeneus (F.) (Coleoptera, Nitidulidae) under laboratory conditions in Scotland, based on the facts that there is only one moult and only one increase in head-capsule width. The egg, first- and second-instar larvae, prepupa and pupa of M. aeneus are described and compared with the corresponding stages of M. viridescens (F.). The larvae of the two species are differentiated for the first time by the arrangement of dorsal cuticular tubercles, the size and form of the urogomphi and the width of the head capsules.

COMPLEXITIES IN THE NUMBER OF LARVAL INSTARS OF THE BIRCH CASEBEARER IN NEWFOUNDLAND (LEPIDOPTERA: COLEOPHORIDAE)

1976 ◽  
Vol 108 (4) ◽  
pp. 401-405 ◽  
Author(s):  
Arthur G. Raske
Keyword(s):  
North America ◽  
Head Capsule ◽  
Fourth Instar ◽  
Larval Instars ◽  
Northeastern North America ◽  
Head Capsule Width ◽  
The Third ◽  
Case Characteristics

AbstractThe birch casebearer, Coleophora fuscedinella Zeller, has five larval instars in northeastern North America, but commonly only four in insular Newfoundland. The occurrence of four larval instars in Newfoundland represents the omission of either the third or the fourth instar. Local Newfoundland populations may have five larval instars, but the late-developing larvae of these populations have only four larval instars. Head capsule width can be used to identify instars but case characteristics are recommended because the bimodality of third instar head widths can cause confusion.

scholarly journals Host plant effect on the number of moultings and head capsule width of the gypsy moth caterpillars

2012 ◽  
pp. 127-138
Author(s):  
Slobodan Milanovic ◽  
Sladjan Milanovic
Keyword(s):  
Gypsy Moth ◽  
Head Capsule ◽  
Larval Instars ◽  
Head Capsule Width ◽  
Sessile Oak ◽  
Turkey Oak ◽  
English Oak ◽  
Host Plant Effect ◽  
Oak Leaves

The effect of four oak species: Turkey oak, Hungarian oak, sessile oak and English oak on the number of moultings and head capsule width of the gypsy moth caterpillars was researched. Host plants have a statistically significant effect on the number of both male and female larval instars. The highest number of larval instars was recorded for caterpillars fed on sessile oak leaves, and the lowest number was recorded for those fed on Turkey oak leaves. Females reared on Hungarian oak and English oak leaves had a normal number of larval instars. Except for 1st instar caterpillars, all other larval instars showed a statistically significant host plant effect on the head capsule width. The widest head capsules were found on caterpillars fed on Turkey oak leaves, and those fed on sessile oak leaves had the narrowest head capsules. The study data on head capsule widths can be practically applied in the determination of the optimal ratio of larval instars in the gypsy moth population, i.e. in the determination of terms for aerial spraying actions.

scholarly journals THE BIOLOGY OF CHORISTONEURA HOUSTONANA (LEPIDOPTERA: TORTRICIDAE), A PEST OF JUNIPERUS SPECIES

1968 ◽  
Vol 100 (7) ◽  
pp. 750-763 ◽  
Author(s):  
E. A. Heinrichs ◽  
Hugh E. Thompson
Keyword(s):  
Constant Temperature ◽  
Pupal Stage ◽  
Head Capsule ◽  
Egg Development ◽  
Larval Instars ◽  
Head Capsule Width

AbstractChoristoneura houstonana (Grote) lays eggs singly in July. Egg development ranged from 8 to 11 days, with the majority hatching 10 days after oviposition.Larvae are solitary, and mine during early instars but later instars feed externally on leaves in shelters made by webbing foliage together. There is one generation each year and overwintering occurs in a hibernaculum, in mined leaves. Field-collected head-capsule width frequencies indicated nine larval instars. Rearing larvae on seedling junipers indoors indicated a range of 8–11 instars.Pupation occurs during June and July in the shelter where the larva feeds. The pupal stage lasted about 10 days at a constant temperature of 80°F.

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