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 Preference and performance of the gypsy moth cater­pillars on sweet chestnut and some oak species

2010 ◽  
pp. 113-124 ◽  
Author(s):  
Slobodan Milanovic
Keyword(s):  
Gypsy Moth ◽  
Sweet Chestnut ◽  
Sessile Oak ◽  
Preference Index ◽  
Mixed Plantations ◽  
Study Results ◽  
Turkey Oak ◽  
And Performance ◽  
Common Oak ◽  
Oak Leaves

In the establishment of mixed plantations, it is necessary to examine previously the relations of the principal and the admixed species and the most significant pests. This paper presents the results of the study of the gypsy moth caterpillar preference and performance on sweet chestnut and four oak species. Preference index is the highest for Hungarian oak (0.83) and Turkey oak (0.77), for sessile oak it is significantly lower (0.33), and for common oak it is equal to 0. In combination with sweet chestnut, the gypsy moth second-instar caterpillars prefer Hungarian oak, i.e. Turkey oak leaves. In combination with sessile oak or common oak, the gypsy moth caterpillars prefer sweet chestnut leaves. The analyzed parameters which characterise the performance of the gypsy moth fourth-instar caterpillars are lower for all study oak species compared to sweet chestnut, except in the case of Turkey oak. Based on the study results and the adopted principle that the mixture should be composed of the most favourable species, which will serve as the 'trap plant' during the gypsy moth outbreak, it can be concluded that Turkey oak is more favourable for the mixture with sweet chestnut than the other analyzed oak species.

scholarly journals Host plant effect on the susceptibility of gypsy moth caterpillars to insecticides

2002 ◽  
pp. 69-78
Author(s):  
Slobodan Milanovic
Keyword(s):  
Host Plant ◽  
Gypsy Moth ◽  
Lymantria Dispar ◽  
Abiotic Factors ◽  
Pedunculate Oak ◽  
Moth Population ◽  
Study Results ◽  
Turkey Oak ◽  
Host Plant Effect ◽  
Oak Leaves

Gypsy moth (Lymantria dispar L) is the most significant pest of broadleaf forests. The dynamics of gypsy moth population depends on several biotic and abiotic factors, but it is also highly dependent on the quality of consumed food. The gypsy moth control increasingly relies on the biological preparations based on Bacillus thuringiensis subspec. kurstaki (Btk) and Lymantria dispar Nuclear Poliedrosis virus (NPV). Chemical preparations are still applied although more rarely, the pyrethroids which include also lambda-cyhalothrin This paper presents the study results of the effect of host plant on gypsy moth caterpillar (Lymantria dispar L) susceptibility to lambda cihalotrine insecticide, by which the study oak leaves were contaminated. The study results show the lowest mortality of the caterpillars fed on contaminated leaves of Turkey oak (17.5%), then pedunculate oak (86.1%), and the highest mortality of caterpillars fed on sessile oak leaves (92%). The rate of the gypsy moth caterpillar development depends on the host plant Susceptibility of the gypsy moth caterpillars to the above preparation depends on the host plant The knowledge of the effect of host plant on insecticide efficiency in gypsy moth suppression would render insecticide utilisation optimal.

RELATIONSHIPS BETWEEN THE PARASITOID HYPOSOTER EXIGUAE AND THE CABBAGE LOOPER, TRICHOPLUSIA NI: EFFECTS ON HEAD-CAPSULE WIDTH, LIVE AND DRY WEIGHTS, AND HEMOLYMPH SPECIFIC GRAVITY OF HOSTS AT DIFFERENT AGES

1975 ◽  
Vol 107 (9) ◽  
pp. 927-934 ◽  
Author(s):  
Gerard F. Iwantsch ◽  
Zane Smilowitz
Keyword(s):  
Specific Gravity ◽  
Trichoplusia Ni ◽  
Dry Weight ◽  
Head Capsule ◽  
Cabbage Looper ◽  
Host Age ◽  
Head Capsule Width ◽  
Growth Increments ◽  
Developmental Parameters

AbstractThe effects of parasitism by Hyposoter exiguae (Viereck) on certain developmental parameters of Trichoplusia ni (Hübner) were influenced by host age at parasitism.Head-capsule growth increments for parasitized Trichoplusia ni became smaller with each successive molt during parasitism so that determination of instar on the basis of head-capsule width became impossible.Parisitized T. ni showed a proportionately smaller gain in weight from time of stinging until parasitoid emergence the older they were when stung (6 times for 3rd instars; 2 times for 4th instars; and no gain for 5th instars). This retardation was evident 24 h after parasitism. Essentially the same results were obtained for dry weight.Percentage dry weight of parasitized larvae tended to increase over control values until the 5th stadium when controls abruptly increased. Values for parasitized 5ths remained below the controls. Values found on the last days reflected those of the parasitoid which composed most of the mass inside the host cuticle.Hemolymph specific gravity in controls and parasitized 3rd instars oscillated with a frequency of one stadium in the 3rd, 4th, and early 5th stadia. Specific gravity of controls then rose to a maximum of 1.0501 in the prespinning phase and dropped by the pharate–pupal phase. Values for parasitized larvae in the 5th stadium rose slightly before leveling off, and parasitized 5th instars rose to a maximum on the next-to-last day. Maximum values attained for hosts parasitized as 3rd and 5th instars never reached that for controls on day 11. This may be related to the complete unacceptability or unsuitability of T. ni larvae for parasitism from day 11 on.

Determination of Larval Instars of Semanotus bifasciatus (Coleoptera: Cerambycidae) Based on Frequency Distributions of Morphological Variables

2020 ◽  
Vol 55 (3) ◽  
pp. 405-415
Author(s):  
Na Li ◽  
Lei Wu ◽  
Yongxin Geng ◽  
Danfeng Wei ◽  
Min Chen
Keyword(s):  
Body Length ◽  
Larval Instar ◽  
Head Capsule ◽  
Larval Instars ◽  
Frequency Distributions ◽  
Larval Stages ◽  
Field Investigations ◽  
Mandible Length ◽  
Morphological Variables

Abstract Semanotus bifasciatus Motschulsky (Coleoptera: Cerambycidae) is one of the most destructive pests of Platycladus trees in China. Morphological measurements, such as head capsule (HC) width, can be very useful and practical indicators for identifying larval instars of coleopteran species. In this study, six morphological variables, including HC width, pronotum width, mandible length and width, and body length and width were measured to determine the instars of field-collected larvae of S. bifasciatus. Both the HC width and pronotum width were reliable parameters for determining the instar and stage. Larvae of S. bifasciatus were divided into eight instars; we detected strong relationships between larval instar and both the HC width (R2 = 0.9640) and pronotum width (R2 = 0.9549). The ranges of body widths and lengths for each instar are provided as reference values for distinguishing among larval stages in field investigations.

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.

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