Larval instars determination for the European Grapevine Moth (Lepidoptera : Tortricidae) based on the frequency distribution of head-capsule widths
Auteurs : Delbac (Lionel), Lecharpentier (Patrice) et Thiéry (Denis)
Année de publication : 2010
Publication : Crop Protection
Volume :
29
Fascicule : 6
Pagination : 623-630
Résumé :
pplyBrkRules··-·Morphological measurements such as head-capsule (HC) width can be very/ useful and accessible tools that may be employed for classifying/ Lepidopteran larval instars according to stage of life history. The/ availability of such measures is crucial in the management of larval/ pests, because their control relies upon making accurate assessment of/ the life history stage at which larvae has reached in various/ environmental conditions. Such forecasts are then used in order to/ estimate the timing of emergence for future adult populations./ Previous studies investigated the use of head-capsule widths from/ field larvae of European Grapevine Moth (EGVM), Lobesia botrana Den./ and Schiff., to describe the distributions of the five instars during/ three generations of the insect. The observations were performed in/ 1998 and 2002 in a vineyard near Bordeaux. The results presented here/ increase the scope of earlier methods by providing statistical/ confidence. Our method was calibrated on a large number of individuals/ (N = 552) issued from our insect culture and uses a nonlinear/ least-squares parameter estimation to describe the distribution of/ each larval instar inside each generation. The model was tested on a/ wild larval population (n = 3007) occurring in our experimental/ vineyard during two complete years. The instar class ranges and/ boundaries were characterized with the associated probabilities of/ misclassification. A final classification statistical model is/ developed for each instar and each generation. From this study, we/ conclude that larval HC sizes increase statistically according to the/ generation of the year, and thus is influenced by grape phenology. The/ statistical tool may be easily used either by technicians or/ scientists to determine the larval phenological development of wild/ populations of the EGVM. The extension of the model to other moths is/ discussed. [copyright]2010 Elsevier Ltd. All rights reserved. SN··-·0261-2194 UT ZOOREC:ZOOR14611075073 /ER··-·