| Abstrakt: |
Abstract: a1_Though extra instars are often associated with poor conditions and thought to be a compensation for a low growth rate, the reasons why they are necessary, and for variable instar number existing under standard rearing conditions, are not yet clear. In standard rearing conditions, approximately half of Pseudocoremia suavis larvae had five instars (Type I larvae), and half six instars (Type II larvae). Type II larvae took longer to pupate and reached higher pupal weights than Type I larvae. The extra instar was not related to sexual size dimorphism; Type II larvae were not more likely to be females. Females of both Types pupated later than males and had higher pupal weights; this weight gain was achieved wholly via an extended final instar. Relative growth rates (RGR), instar durations and larval weights on weigh days were otherwise the same for both sexes. For most of the larval period, Type II larvae had lower RGR and lower weights than Type I larvae. They also had shorter 3rd, 4th and 5th instars than Type I larvae, and the estimated weights at each moult were significantly lower. |
