Effect of low temperature in the development cycle of Lucilia sericata (Meigen) (Diptera, Calliphoridae): implications for the minimum postmortem interval estimation

Knowledge of necrophagous insects' developmental data is necessary for the forensic entomologist to estimate a reliable minimum postmortem interval (PMImin).Among the most represented necrophagous species,Lucilia sericata (Diptera,Calliphoridae) is particularly interesting.It is regularly identified in samples,with a predominance in summer,and is commonly used by analysts of our entomology department (Institut de Recherche Criminelle de la Gendarmerie Nationale) to estimate the PMImin with the accumulated degree days (ADD) method.This method requires the mathematical lower thermal threshold to be known.This value dictates the quality of the applied ADD method but cannot be considered as fixed,especially when insect development occurs at temperatures close to the biological threshold.In such conditions,it is necessary to study the influence of such temperatures on development rate,as well as the consequences of estimating the period of first oviposition on cadavers,when using the ADD method.Seven replicate rearings were conducted at six different temperatures: 30 ℃,24 ℃,18 ℃,15 ℃,12 ℃ and 10 ℃.Time of development and time of emergence were recorded.The effect of low temperature on the development cycle and the reliability of the ADD method under this entire temperature spectrum were studied using different linear regression models.Calculated durations of total insect time development and experimental rearing duration were then compared.A global linear model cannot be used on the whole temperature spectrum experienced by L.sericata without resulting in an overestimation at some temperatures.We found a combination of two linear regression models to be suitable for the estimation of the total development time,depending on the temperature experienced by L.sericata.This approach allowed us to obtain a variation lower than 2% at 12 ℃ and 10 ℃ between the calculated duration and experimental duration of development.In comparison,the results obtained with a global model show a variation higher than 3% at 12 ℃ and 10%at 10℃.

Applicability of remote sensingbased surface temperature regimes in determining deciduous phenology over boreal forest

Aims The study of deciduous phenology over boreal forest is important for understanding forest ecology and better management.In this paper,our objective was to determine the phenological stages of deciduous leaf out(DLO)over the deciduous-dominant[i.e.trembling aspen(Populus tremuloides)]stands in the Canadian Province of Alberta.Methods During the period 2006–08,we used Moderate Resolution Imaging Spectroradiometer(MODIS)-based 8-day surface temperature(TS)images to calculate accumulated growing degree days(AGDD:a favourable temperature regime for plant growth).The temporal dynamics of AGDD in conjunction with in situ DLO observations were then analysed in determining the optimal threshold for DLO in 2006(i.e.80 degree days).Important Findings The implementation of the above-mentioned optimal threshold revealed reasonable agreements(i.e.on an average 91.9%of the DLO cases within ±2 periods or ±16 days of deviations during 2007–08)in comparison to the in situ observed data.The developments could be useful in various forestry-related applications,e.g.plant growth and its ability of exchanging atmospheric carbon dioxide,forest ecohydrology,risk of insect infestation,forest fire and impact of climate change,among others.

A Statistical Comparison of the Westerly Wind Bursts between the Positive and Negative Phases of the PDO

To understand the diversity of the El Ni?o–Southern Oscillation(ENSO)under the background of Pacific decadal oscillation(PDO)during recent decades,characteristics of westerly wind bursts(WWBs)during positive and negative phases of the PDO were analyzed.It is shown that,during the ENSO developing period,the El Ni?o evolution may be affected by stronger or more frequent WWBs in the positive PDO phase than in the negative PDO phase.The sustained effects of atmospheric dynamics on the equatorial ocean can be indicated by the accumulated WWB strength,which contains most WWB characteristics,including the accumulated days,occurrence frequency,strength,and spatial range of WWBs.The synoptic/climate systems that are directly related to WWBs show a wider spatial distribution in the positive PDO phase than in the negative PDO phase.