DEVELOPMENT OF DIAPREPES-ABBREVIATUS (COLEOPTERA, CURCULIONIDAE) ON ARTIFICIAL AND CITRUS ROOT SUBSTRATES

Measurement of head capsule widths showed that larvae of D. abbreviatu s generally have 10 or 11 instars when reared on artificial diet. The growth ratio for head capsules was greater during stadia for the 1-5th instars and declined after the Gth. Head capsule widths and larval gr owth increased steadily for 71 d, at which time, all larvae were 7-10t h instar. Larval growth reached a plateau at 114 d during stadia at 9- 11th instar and remained unchanged to 188 d, The mean time for develop ment of Ist to 7th instars was less compared with instars >7th. A freq uency distribution based on head capsule size for greenhouse- and fiel d-collected larvae fed citrus roots over time had similar stadia peaks to larvae reared on artificial diet in the laboratory. Weight of larv ae with head capsule widths <1.0 mm increased slowly within stadia, wh ereas a greater increase in larval weight was observed for larvae with capsule widths >1.0 mm. Variation in larval Height for each stadium w as also greater for larvae with head capsule widths >1.0 mm. Most larv al weight gain occurred during stadia at 6-8th instar, suggesting high er food consumption at these developmental stages. Larval weight incre ased steadily within the initial 71 d but declined slowly thereafter. The mean weight for instars reared on artificial diet was greater than for either greenhouse- or field-collected larvae. The mean weight for larvae fed citrus roots in the greenhouse was smaller than for larvae feeding on roots in the field. On artificial diet, only a few larvae developed to pupae. Approximately 70% of the larvae pupated at the 10t h instar, whereas others pupated at the 11th instar, The mean time +/- SEM required for larval development to pupae, larvae to adult, and pu pae to adult was 153.3 +/- 28.0 d, 158.3 +/- 20.7 d, and 17 +/- 3.8 d, respectively. Mean larval weight before pupation was 480.1 +/- 102.5 mg, mean pupal weight 378.2 +/- 66.1 mg, and mean adult weight 276.0 /- 51.6 mg. Larvae lost 20.3% of their live weight during metamorphosi s to pupae and pupae lost 24.7% of their in weight in becoming adults.