Length-weight relationship of fishes from Anambra ... - Zoo-unn.org

Oviposition, fecundity and development of the hide beetle49Table 1: Developmental parameters of D. maculatus in different fish moisture levelsTreatments Fishmoisturecontents(%)Preovipositionperiod(days)Ovipositionperiod(days)Numberof eggslaidNumberof eggshatchingto larvae(%)Number oflarvaedevelopingto pupae(%)No. ofpupaeemergingas adult(%)Control 14 12 20 54 43(79.63) 14(33.56) 10(71.43)1 36 5 8 164 115(70.12) 29(25.22) 21(72.41)2 41 6 7 59 39(66.10) 14(35.54) 12(85.71)3 56 5 9 147 133(90.48) 22(16.54) 20(90.9)4 66 5 6 97 73(75.26) 28(38.36) 14(50.0)5 73 4 8 246 102(41.46) 28(27.45) 24(85.71)6 77 3 8 598 120(20.07) 30(25.0) 20(66.07)Duration of larvalemergence (days)2520151050y = -0.185x + 21.448r = 0.960 50 100Fish moisture content (%)Figure 1: Duration of larvalemergence in relation to fishmoisture contentfifth instars measured 3.28±0.71 mm (range 2-4 mm), 6.06±0.82 mm (range 5-7 mm),8.04±0.75 mm (range 7-9.5 mm), 10.83±0.97mm (range 10-12 mm) and 13.0±0.29 mm(range 12.5 – 13.5 mm) in length respectively.Thus, the larvae grew bigger as they becameolder. The larvae bored into the fish flesh andhead capsule and fed voraciously, reducing thefish to fragments and powder. The late instarlarvae were found mostly in the head capsule.The mean larval developmental period increasedwith increase in fish moisture content and therewas a very strong correlation between them (r= 0.93) (Fig.2). The mean larval developmentalperiod lasted from 16 to 23 days. Over 61% ofthe larvae in each treatment died and,therefore, did not develop to the pupal stage,though virtually no correlation existed betweenthe percentage dead larvae and fish moisturecontent (r = 0.23). The pre-pupa stage lasted2-4 days. It was reached when the late instarMean larval developmentperiod (days)2524232221201918171615y = 0.1121x + 14.474r = 0.930 50 100Fish moisture content (%)Figure 2: Mean larvaldevelopment period in relationto fish moisture contentlarvae stopped all physical activities, such asfeeding and movement.Pupal Development: The percentage ofpupae which emerged from the larvae in eachtreatment was remarkably low. It ranged from17% in treatment 3 to 38% in treatment 4,though no definite pattern was discerned (Table1). A strong positive correlation (r = 0.86)existed in the inverse relationship between thetime it took all the pupae to emerge and fishmoisture content (Fig. 3). The pupae werewhite in colour and measured 7.65±0.79 mm(range 7-8.6 mm) in length. The percentagedead pupae fluctuated without any definitepattern and showed a total lack of correlation (r= 0.09) with the fish moisture content.Adult: Between 50 and 91% of adults emergedfrom the pupae in all treatments (Table 1). Thenewly hatched adult, often found in the headcapsule, had reddish-brown head and yellowish-