Water relations of insecticide resistant and susceptible German cockroaches (dictyoptera: Blattellidae)

Abstract

1. 1. Percentage total body water content (%TBW), cuticular permeability (CP), and rate of water loss were determined for insecticide resistant and susceptible strains of the German cockroach, Blatlella germanica (L.). 2. 2. Initial body mass ranged from means of95.52–122.72mg, for female insecticide susceptible (ACY strain) and resistant (Maple) strains, respectively. Initial body mass of males ranged from means of 58.36 mg for a resistant strain (109) to 65.18 mg for a susceptible strain (Black). There were no differences in initial mass of nymphs among strains. 3. 3. Mean % total body water (%TBW) ranged from 68.21 to 71.95 for adult males, 66.78–71.89 for adult females and 70.56–71.61 for nymphs. ACY strain adults had greater %TBW than the other strains. There were no differences in %TBW of nymphs among strains. 4. 4. Mean cuticular permeabiity was not affected by initial mass for any stage or strain and ranged from 11.34 to 32.69 μg/cm 2/hr/mmHg for nymphal and male susceptible strain (Black) B. germanica, respectively. 5. 5. Cumulative mass and %TBW lost increased linearly with desiccation time. 6. 6. Water relations of B. germanica are not related to levels of insecticide resistance.