Diatomaceous Earth-Induced Changes in the Life-History Traits in Musca domestica L. (Diptera: Muscidae)
The present investigation was split into the following five experiments:
Experiment One: Using doses of 0.0, 0.2, 0.4, 0.6 and 0.8 mg/l00ml diatomaceous earth (DE) in the larval food medium, a mean LC50 of 0.66mg/l00ml was determined for the 31instar larvae of M domestica. Experiment Two: Here the time-course mortalities of the 3rd-instar larvae were evaluated, wh
ere larval mortalities were counted after 24h, 48h and 72h. Results indicated that longer period of DE exposure caused higher larval deaths in the experimental insects. Experiment Three: Inheritance of the effects of DE in life-history traits from parental to F2 generation showed that the DE is capable of inducing effects on all the life-history traits in a dose-dependent manner in the parental generation. In subsequent generations, the egg-hatch characteristic diminished, and except fecundity and pupal duration, all other traits were not affected statistically by DE doses. Experiment Four: Treatments of LC50 DE resulted in the increment of the length of the salivary glands in M domestica, while the gland width was unaffected. This change in salivary gland morphometrics in the flies might have induced some significant genetic alterations manifested in the altered life-history traits in the parental through F2 generations. Experiment Five: Genetic compatibility study between the regional strains of houseflies from Rajshahi (RAJ), Rangpur (RAN) and Dinajpur (DIN) involving 3 x3= 9 reciprocal crosses revealed that traits like fecundity, larval duration, number of dead larvae, pupal duration, number of dead puape and the number of adults emerged differed significantly in the experimental flies. However, despite the above differences, the regional flies were fully compatible because of the fact that the egg-hatch percentages in all the crosses were fairly above 50%. Nevertheless, the present findings have some practical implications in the sense that the fluctuations in the fecundity and egg-hatch percentages of the mating pairs could be integrated with the DE treatment protocol to achieve the maximum benefit for any control strategy for this important vector species.