Population dynamics of the coconut caterpillar, Opisina arenosella Walker (Lepidoptera: Xyloryctidae), in Sri Lanka

1988 ◽  
Vol 78 (3) ◽  
pp. 479-492 ◽  
Author(s):  
P. A. C. R. Perera ◽  
M. P. Hassell ◽  
H. C. J. Godfray
Keyword(s):  
Population Dynamics ◽  
Sri Lanka ◽  
Dynamics Analysis ◽  
Triggering Mechanism ◽  
Working Hypothesis ◽  
Opisina Arenosella ◽  
Population Outbreaks ◽  
Pupal Parasitism ◽  
Generation Period

AbstractOpisina arenosella Walker is a defoliating pest of coconut in Sri Lanka. A first attempt was made to understand its population dynamics. Analysis of records of population outbreaks throughout the country from 1965 to 1985 revealed cycles in the population of approximately one generation period, giving the population the appearance of partially discrete generations. There was also evidence for longer cycles of six-month period. Outbreaks occurred throughout the coconut-growing regions of Sri Lanka, and the numbers of outbreaks per year in different provinces were sometimes correlated, indicating a common, probably climatic, triggering mechanism. Parasitism remained high throughout the outbreaks and there was some evidence that pupal parasitism increased towards the end of an outbreak. A working hypothesis that explains the population dynamics of O. arenosella and the origin of outbreaks is presented.

scholarly journals Population dynamics of the coconut caterpillar, Opisina arenosella Walker (Lepidoptera: Xyloryctidae), in Sri Lanka

COCOS ◽  
2010 ◽  
Vol 7 (0) ◽  
pp. 42 ◽  
Author(s):  
P. A. C. R. PERERA ◽  
M. P. HASSELL ◽  
H. C. J. GODFRAY
Keyword(s):  
Population Dynamics ◽  
Sri Lanka ◽  
Opisina Arenosella

scholarly journals Population Dynamics and Breeding Preference of Aedes Aegypti and Ae. Albopictus Attributing to Dengue Threat in Kelaniya Medical Officer of Health Area in Sri Lanka

2021 ◽  
Author(s):  
L D Amarasinghe ◽  
P. V J. Nadeeka
Keyword(s):  
Population Dynamics ◽  
Sri Lanka ◽  
Aedes Aegypti ◽  
Medical Officer ◽  
Abundant Species ◽  
Mixed Population ◽  
Weather Factors ◽  
Dengue Transmission ◽  
Risk Areas ◽  
Indoor And Outdoor

Abstract Background Aedes aegypti and Ae. albopictus are the two species of dengue vector mosquitoes in Sri Lanka. Indoor and outdoor distribution of these species, their population dynamics and breeding preference are important factors determining the dengue transmission. Gampaha district in Sri Lanka reported to have frequent dengue epidemics from recent past, hence this study was conducted.Methods Ovitrap surveillance was conducted to determine the vector species distribution in indoor and outdoor in Kelaniya Medical Officer of Health (MOH) area of the Gampaha district. Larvae were reared in the laboratory until adults were emerged to identify species morphologically. Breeding preference of vector mosquitoes were carried out by physically observing the presence of mosquito larvae in water collected receptacles in the area. Results Aedes aegypti and Ae. albopictus were reported to distribute throughout Kelaniya MOH area as a mixed population. Ae. albopictus is the most abundant species both indoor and outdoor in Kelaniya MOH area compared to Ae. aegypti. Weather factors, rain days and wind positively correlated with Aedes population. Conclusions Aedes aegypti and Ae. albopictus are frequently present in Kelaniya MOH area as mixed population. High risk areas of the study area were identified.

Two New Competition Indexes on the Basis of Lotka-Volterra Competition Model

2013 ◽  
Author(s):  
Huayong Zhang ◽  
Tousheng Huang ◽  
Liming Dai
Keyword(s):  
Population Dynamics ◽  
Equilibrium Point ◽  
Interspecific Competition ◽  
Competition Model ◽  
Volterra Model ◽  
Dynamics Analysis ◽  
Competitive Process ◽  
Stability Of Equilibrium ◽  
The Stability ◽  
Strength Of Competition

In this research, two competition indexes, competing capacity and competing tensor, are brought forward to better understand the interspecific competition between species. With the employment of the two indexes, the competitive process in Lotka-Volterra model can be described much clearly. The strength of competition for a species is divided into three competition grades according to the competing tensor. In the interspecific competition, when two species are in different competition grades, the weak species will be excluded; when two species are in the same grade, the coexistent equilibrium will present. Two cases are studied with the methods by employing the two indexes. In the second case, the stability of equilibrium point is determined by the competing tensor. The new indexes have shown potential in population dynamics analysis.

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