MESOCYCLOPS LONGISETUS EFFECTS ON SURVIVORSHIP OF AEDES-AEGYPTI IMMATURE STAGES IN CAR TIRES

The effect of the introduction of the entomophagous copepod Mesocyclop s longisetus (Acuacultura F.C.B. strain) on the survival of Aedes aegy pti immature stages in car tyres was evaluated under semi-natural cond itions in the municipality of Merida, Yucatan, Mexico. Life tables wer e constructed for the immature stages of the mosquito in the presence and absence of M. longisetus, and the survival data were compared usin g log-linear models. The data set was adjusted using the GLIM statisti cal package and the quality of adjustment was evaluated with a chi-squ ared test. Survivorship curves were constructed for each treatment. In the absence of M. longisetus, the survivorship of Ae. aegypti immatur e stages averaged 9%. The highest mortality rate was observed during t he fourth larval instar (54%) and the resulting survival pattern corre sponded to a type II survivorship curve. The mortality rate of Ae. aeg ypti first-instar larvae (fifty per tyre) increased more than 200-fold in the presence of M. longisetus (twenty per tyre) and the highest mo rtality was during the first two larval instars, where it reached 98.9 %, with a resulting survivorship of 0.2%. Overall mortality was sixfol d greater in the presence of the copepod than in its absence. The surv ival pattern of immature stages of Ae. aegypti in the presence of the copepod corresponded to a type III survivorship curve. As M. longisetu s was so effective against Ae. aegypti immature stages in tyres under seminatural conditions, its long-term effectiveness should be evaluate d under socially and ecologically realistic field conditions in Mexico .