Determination of larval instar of Conotrachelus perseae Barber (Coleoptera: Curculionidae)

Abstract

The aim of this study was to determine the number of larval instars of Conotrachelus perseae Barber. Three-hundred twenty-three larvae were collected from avocado fruit of the cultivars Hass, Fuerte and criollo (Persea americana var. drymifolia), and head capsule width of each larva was measured. Data were analyzed with Dyar's rule and Hcap program. The frequency distribution analysis showed four distinct distribution peaks of the head capsules widths. Dyar's constant averaged 1.49, where the relationship between the natural logarithm of the head capsule widths and the number of larval instar resulted in a perfect geometric growth for each larval stage. The excellent fit to a linear model indicated that no instar was overlooked, and the analysis distinguished four larval instars of C. perseae.