Broad (br), a transcription factor containing the Broad-Tramtrack-Bric-a-brac (BTB) and zinc finger domains was shown to mediate 20-hydroxyecdysone (20E) action and pupal development in Drosophila melanogaster and Manduca sexta. We determined the key roles of br during larval-pupal metamorphosis using RNA interference (RNAi) in a coleopteran insect, Tribolium castaneum. Two major peaks of T. ca...

Ultrastructure, development and histopathology of a new densonucleosis vlrus of bloodsucking mosquitoes are described. Mosquito densonucleosis virus is infective to all 4 larval instars, pupae and adults of both sexes. Incubation periods were significantly shorter in older fourth-instar larvae than in third-instar larvae. Infected larvae die during the fourth larval instar or as pupae. The limi...

The larval growth of Liosarcophaga dux Thompson (Diptera: Sarcophagidae) was studied under varying indoor room temperatures in Malaysia. Five replicates were established. The immature growth of this species from first instar until adult emergence was 307.0+/-3.0 hours. The mean larval length measured for second instar, third instar, post-feeding stage and puparia were 6.5+/-0.5 mm (n=10), 11.8+...

Determination of the most sensitive and susceptible organismal life stage is important for use of the organism in toxicity assessments of environmental pollutants. In the present study, the sensitivities and susceptibilities of larval developmental stages of two black fly sibling species, Simulium vittatum Zetterstedt cytospecies IS-7 and S. vittatum Zetterstedt cytospecies IIIL-1, were determi...

Laboratory bioassays showed that the susceptibility of Simulium vittatum to Neoaplectana carpocapsae increased with successive larval instars. First, second, and third instar larvae were resistant to infection, while seventh instars were highly susceptible. Significant differences in intra-instar susceptibility were also evident, as mortality ranged from 58% for the smallest seventh instar larv...

Recent data suggest that oxygen limitation may induce moulting in larval insects. This oxygen-dependent induction of moulting (ODIM) hypothesis stems from the fact that the tracheal respiratory system of insects grows primarily at moults, whereas tissue mass increases massively between moults. This may result in a mismatch between oxygen supply and demand at the end of each larval instar becaus...

We studied larval development and acquisition of metabolic resources in Drosophila melanogaster selected for adult desiccation resistance. Desiccation-selected (D) flies had longer developmental times in comparison with control populations, resulting in significantly higher body mass. No differences were found in larval growth rates, suggesting that increased body mass results from the extended...

Many field studies of insects have focused on the adult stage alone, likely because immature stages are unknown in most insect species. Molecular species identification (e.g., DNA barcoding) has helped ascertain the immature stages of many insects, but larval developmental stages (instars) cannot be identified. The identification of the growth stages of collected individuals is indispensable fr...

Derived members of the endoparasitic order Strepsiptera have acquired an extreme form of sexual dimorphism whereby males undergo metamorphosis and exist as free-living adults while females remain larviform, reaching sexual maturity within their hosts. Expression of the transcription factor, broad (br) has been shown to be required for pupal development in insects in which both sexes progress th...