Positive mortality effects in container mosquitoes

Cohorts of 150 newly-hatched <i>Aedes aegypti, A. albopictus, A. triseriatus, </i>and <i>Culex pipiens</i> were separately reared in 500 mL plastic containers. Cohorts were randomly assigned a treatment of either simulated mortality random harvest of 0, 10, 30, 50, or 70% removal on day 2 of the experiment, or mortality from predation by 1, 2, or 3 female <i>Mesocyclops longisetus </i>added on day 0 and removed on day 2. Any random harvest treatment cohorts that had fewer survivors than the number required to simulate their assigned mortality percentages from 150 had larvae added to reach the appropriate number. The conspecific larvae removed from other harvest treatments were used for these additions to ensure they were reared under the same conditions. On day 2, the number of survivors was counted for each cohort, and the amount of mortality experienced up to that point (Day2mort) was calculated as (#survivors - 150)/150. The experiment was conducted in 8 unbalanced temporal blocks. Four days prior to the start of the experiment, the experimental containers were filled with 400mL reverse-osmosis water, 1g dried live oak (<i>Quercus virginiana</i>) leaves, 0.05g dried decorated crickets (<i>Gryllodes sigillatus</i>), and 100 microliters microbial inoculum collected from a rain-filled bucket. Lids were placed on the containers with holes punched for ventilation. 0.5g dried oak leaves and 0.025g dried decorated crickets were added on days 16 and 30 for the three <i>Aedes </i>species cohorts and on days 9, 16, 23, and 30 for the <i>C. pipiens </i>cohorts. Containers were housed in an environmental chamber at 25C with a 14:10 light:dark photoperiod throughout the experiment.Containers were checked daily for pupae, which were removed, placed in glass vials with water and cotton stoppers, and housed in the same environmental chamber. Pupae were checked daily for adults, which were removed and sexed. The number of days to pupation (DaystoP) and to adulthood (DaystoA) were recorded for each individual.