IDENTIFICATION OF LARVAL INSTARS OF AEDES-ALBOPICTUS (SKUSE) AND AEDES TRISERIATUS (SAY) (DIPTERA, CULICIDAE) BASED ON HEAD CAPSULE SIZE

Effects of constant temperature (15, 23, 31 degrees C) on the head cap sule widths of the larval instars of Aedes albopictus (Skuse) and Aede s triseriatus (Say) were determined in the laboratory. For both specie s, head capsule widths were significantly different between instars (P <0.001). Temperature significantly affected the size of head capsules of larvae of both species. For Ae. albopictus, except for the Ist inst ar, mean head capsule widths of 2nd-4th instars tended to be larger at 23 degrees C than at 15 or 31 degrees C; while for Ae. triseriatus, m ean head capsule size was largest only at 23 degrees C for 3rd and 4th instars. However, for both species, mean head capsules widths were si gnificantly (P<0.05) larger at 23 degrees C than at the other two temp eratures only for 4th instars. The head capsule widths of all instars of Ae. triseriatus were larger than for the corresponding instars of A e. albopictus. Using classification criteria developed through discrim inant analysis, >98% of larvae of both species were identified to inst ar regardless of the temperature in which the larvae were reared.