No abstract

An experiment was conducted on age- specific variation of body mass (BM) and lipid reserves (LR) in Periplaneta americana (L.) (Blattodea: Blattidae). The BM and LR of adult females and males of P. americana fluctuated with age and the females were heavier and loaded with more lipids than the males. The BM and LR of both female and male P. americana showed positive correlation. In an another study on relationship between adult female BM and fecundity we found that an adult female fails to produce an ootheca or does not become reproductively active, until she attains a BM of 1.27 to 1.40 g; as such, 1.27 g may be considered the ‘threshold body mass’ below which a female fails to produce an ootheca. Moreover, positive and highly significant correlations between the female BM and ootheca number (ON) (r = 0.743) and BM and ootheca mass (OM) (r = 0.747) supported the idea that females with BM above the ‘threshold’ produce healthier oothecae with heavier offspring.

Application of juvenile hormone III (JH III) and a JH analogue, methoprene to last instars of Periplaneta americana suppressed adult emergence and caused morphological abnormalities such as twisted wings and asymmetry of appendages resulting in formation of either nymphoids or giant supernumerary nymphs and adultoids. The effects of JH III and methoprene were concentration dependent in inducing aberrations in morphogenetic moult as well as in significantly lowering the body mass (BM) and lipid reserves (LR) in P. americana.