scholarly journals Phenology of Population of Immature Stages of Pear Psylla, Cαcopsyllα pyri, in the Region of Magnesia (Greece)

2017 ◽  
Vol 10 ◽  
pp. 11 ◽  
Author(s):  
E. T. Stratopoulou ◽  
E.T. Capatos
Keyword(s):  
Population Density ◽  
Overlapping Generations ◽  
First Generation ◽  
Immature Stages ◽  
Basic Pattern ◽  
Environmental Pressure ◽  
Cacopsylla Pyri ◽  
Pear Psylla ◽  
Low Levels

The phenology of the population of immature stages of pear psylla, Cacopsylla pyri (L.), was studied in Greece (region of Magnesia), during the period 1988-1991 and it was found to follow a basic pattern. Pear psylla produces 5-6 gencrations per year. The first generation develops during the period February-middle April and it is quite discrets. Three overlapping generations are developed during the period front middle April until middle August but the amount of overlapping varies front year to year. Front middle August until the end of the season pear psylla produces 1-2 generations, i.e. only a part of the firth generation complotes the sixth one. Population density is generally low during the first generation but during May-June reaches verty high levels. During sommer, strong environmental pressure, supresses the population of pear psylla to low levels but it recovers again during September-October.

scholarly journals Distribution of Population of Immature Stages of Pear Psylla, Cαcopsyllα pyri, within the Tree and Development of Sampling Strategy

2017 ◽  
Vol 10 ◽  
pp. 5 ◽  
Author(s):  
E. T. Stratopoulou ◽  
E.T. Capatos
Keyword(s):  
Second Generation ◽  
Sampling Strategy ◽  
Tree Canopy ◽  
Oviposition Period ◽  
Immature Stages ◽  
Flower Buds ◽  
Uniform Pattern ◽  
Cacopsylla Pyri ◽  
Pear Psylla ◽  
Oviposition Sites

The distribution of Cacopsylla pyri (L.) (Homoptera-Psyllidae) infestation within the tree canopy and in the varions organs of the tree was investigated in the region of Magnesia (Greece) during 1988 and 1989. The upper parts of the tree canopy and the sections ori­entated to South and west were infested heavier during winter and spring. Later in the scason the infestation was diffused within the tree canopy and at the end of the season a rather uniform pattern of distribution was observed. During the first oviposition period (February-March), the preferred oviposition sites were flower buds white during spring (second generation) they were the leaves of flower buds and young shoots. Sampling strategy for the study of populations of immature stages of pear psylla is discussed on the oasis of these findings.

Selection for monocrotophos resistance in pear psylla,Cacopsylla pyri(L.) (Hom., Psyllidae)

1995 ◽  
Vol 119 (1-5) ◽  
pp. 507-510 ◽  
Author(s):  
S. Berrada ◽  
T. X. Nguyen ◽  
D. Merzoug ◽  
D. Fournier
Keyword(s):  
Cacopsylla Pyri ◽  
Pear Psylla ◽  
Selection For

Liver Glycogen Reserves of Interacting Resident and Introduced Trout Populations

1961 ◽  
Vol 18 (1) ◽  
pp. 125-135 ◽  
Author(s):  
P. W. Hochachka
Keyword(s):  
Population Density ◽  
Liver Glycogen ◽  
Salmo Gairdneri ◽  
Recovery Rates ◽  
Introduced Populations ◽  
Wild Trout ◽  
Low Levels ◽  
Glycogen Stores ◽  
Salmo Clarki

Three groups of trout, two introduced populations of Salmo gairdneri and a resident Salmo clarki, were studied in stream sections. Liver glycogen deposits, which were reduced to low levels during transportation to the stream, were restored in 2 to 3 weeks in all groups, with recovery rates being approximately inverse to the population density. Within the hatchery groups, larger fish laid down greater glycogen stores. Wild trout maintained their high glycogen reserves throughout the experiment.

Causes of Variations in Effectiveness of Bracon cephi (Gahan) (Hymenoptera: Braconidae) as a Parasite of the Wheat Stem Sawfly

1963 ◽  
Vol 95 (2) ◽  
pp. 113-126 ◽  
Author(s):  
N. D. Holmes ◽  
W. A. Nelson ◽  
L. K. Peterson ◽  
C. W. Farstad
Keyword(s):  
Host Plants ◽  
First Generation ◽  
Second Generation ◽  
Wheat Stem Sawfly ◽  
Sawfly Larvae ◽  
Early Ripening ◽  
Low Levels ◽  
One Year ◽  
High Level

AbstractAdults of B. cephi emerged at the same time as the adults of their host, the wheat stem sawfly, and started to oviposit about mid-July. The second generation started to emerge between August 5 and 15. This generation, which was complete in some years, was apparently only partial in years in which adults of the first generation continued to oviposit late in the season. In most cases the larvae of Bracon that were present at harvest time were from eggs laid after August 1.Most of the overwintering B. cephi were located in the lower internodes of the sawfly-infested wheat stems. Although B. cephi attacked some sawfly larvae in their stubs most sawflies escaped parasitism once they had cut their host stems.High host densities per stem in hollow-stemmed wheats were detrimental to Bracon during the early part of the season as the unparasitized sawfly larvae in stems containing B. cephi destroyed the parasite larvae.The sawfly-susceptible wheats were more suitable than the resistant for parasitism. Generally, differences in parasitism between wheats and between barleys were caused by differences in length of survival of the sawfly larvae in the different host plants; longer survival led to higher parasitism.The fluctuations in amounts of parasitism mainly depended on the synchronization of development between B. cephi and the sawfly. Parasitism increased when the sawfly larvae cut their host stems sufficiently late to allow establishment by the second generation of B. cephi and decreased when the sawfly cut too early for parasitism by the second generation. The date of ripening of the host plant governs the date of cutting by the sawfly; hence, the amount of parasitism is influenced by the levels of soil moisture and temperature during the growing season, by differences in rate of development of various plant hosts, and by the date of seeding. Low levels of parasitism resulted from early ripening of the sawfly host plants in two consecutive years, whereas a moderately high level occurred even though the weather of the current year was conducive to early ripening, provided that the wheat in the preceding year had ripened late. It appears that moderate to high levels of parasitism required that the crop ripen late in at least one year out of two.

DESIGN OF A SAMPLING PLAN FOR STUDIES ON THE POPULATION DYNAMICS OF THE CABBAGE MAGGOT, HYLEMYA BRASSICAE (DIPTERA: ANTHOMYIIDAE)

1970 ◽  
Vol 102 (12) ◽  
pp. 1513-1518 ◽  
Author(s):  
M. K. Mukerji ◽  
D. G. Harcourt
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Plant Root ◽  
Immature Stages ◽  
Southwestern Part ◽  
Sample Unit ◽  
Diameter Core ◽  
Sampling Variation ◽  
Hylemya Brassicae ◽  
Cabbage Maggot

AbstractA study of sampling variation in field populations of the cabbage maggot, Hylemya brassicae (Bouché), on cabbage in Ontario, revealed that inter-plant and block differences were rarely significant. For the immature stages, the most appropriate sample unit was the plant root together with a 4- to 6-in. diameter core of soil. The number of samples required was inversely proportional to population density; this relationship was graphed for three levels of sampling precision.The insect is bivoltine in eastern Ontario but has three generations in the southwestern part of the province.

scholarly journals Efficacy of Spirotetramat in the Control of Pear Psylla (Cacopsylla Pyri L.) on Pear Trees in Poland

2012 ◽  
Vol 20 (2) ◽  
pp. 91-106 ◽  
Author(s):  
Krystyna Jaworska ◽  
Remigiusz W. Olszak ◽  
Barbara H. Łabanowska ◽  
Mirosław Korzeniowski
Keyword(s):  
Field Experiments ◽  
Early Stage ◽  
Single Application ◽  
Pest Population ◽  
Total Reduction ◽  
Cacopsylla Pyri ◽  
Summer Generation ◽  
Pear Psylla ◽  
Pear Trees ◽  
Very High

Abstract The effectiveness of spirotetramat in the control of pear psylla (Cacopsylla pyri) on pear trees was investigated in five field experiments, carried out in years 2009- 2011. One or two treatments were applied in June; the first treatment in the early stage of larvae hatching from eggs deposited by females from the summer generation, whilst the second application was carried out about two weeks later. In all the experiments, spirotetramat as Movento 100 SC applied at a dose of 2.25 l/ha effectively reduced the pest population after only a single application (total reduction of larvae after one week post-treatment 75.3-91.4%, and 83.7-97.6% at two weeks posttreatment). Movento 100 SC applied after a single application at a lower dose of 1.8 l/ha had a slightly worse effect (the total reduction of larvae at one week posttreatment was at the level of 58.4-91.3%, and two weeks after application at the level of 56-92.6%) - but in this case only a few larvae at stages L4 and L5 were found on pear shoots. The effectiveness of spirotetramat at both doses after two applications was very high.In comparison with standard insecticides the efficacy of spirotetramat was higher or not significantly different. In two experiments the application of standard compounds such as diflubenzuron and novaluron was not effective in controlling pear psylla and therefore did not prevent damage to pear trees. This may suggest that local populations of the pest are resistant to these measures, especially since they have been used for many years to control other pests of pear trees

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