Estimation of Accumulated Degree Day Value of Six Landmarks within the Pupal Stage of Lucilia sericata

The present paper investigates the pupal development times ofLucilia sericata which were studied in the laboratory at six different constant temperatures （20, 22, 24, 26, 28 ℃ each ± ℃）. Lower thresholds （tL） for development were estimated from the linear regression of the developmental rates on each temperature. These data have made it possible to calculate the ADD （Accumulated Degree-Days） necessary for L. sericata to complete the larval stage and to achieve adult emergence. The minimal duration of development from oviposition to adult emergence was found to be inversely related to temperature. Additionally, six landmarks in pupal development are showed and for each of the landmarks the ADD value was calculated for every rearing temperature involved. These data assist in calculating the duration of the pupal stage based on morphological characteristics and would be of great value for future forensic entomological casework.

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.