Fig 1.
Body temperatures of Locusta migratoria manilensis after infection with Beauveria bassiana.
Comparison of the mean daily body temperatures of L. migratoria manilensis inoculated with 105 spores of B. bassiana /5th instar nymph, and the controls (inoculated with sterile distilled water). Asterisks denote a significant difference in body temperature between infected and non-infected insects (P < 0.05).
Fig 2.
Feeding and basking behavior of infected Locusta migratoria manilensis.
Frequency distribution of L. migratoria manilensis in zone B (basking) and zone F (feeding) in cages providing a heat gradient. Infected locusts were inoculated with Beauveria bassiana (104 spores/ 5th instar nymph). n = 30 in three biological replicates.
Fig 3.
Distribution of infected and uninfected locusts in feeding, basking and resting zones.
Distribution of control and inoculated Beauveria bassiana-infected Locusta migratoria manilensis (104 spores/5th instar nymph) in zone F (feeding), zone B (basking) and zone R (resting). An asterisk denotes a significant difference between infected and non-infected insects (P < 0.05), and NS indicates no significant difference. n = 10 locusts per treatment.
Fig 4.
Impact of thermoregulation duration on mortality of infected locusts.
The cumulative mortality of Locusta migratoria manilensis inoculated with Beauveria bassiana (104 spores/5th instar nymph) following exposure to three regimes of thermoregulation (0 h, 3 h and 6 h per day are indicated by filled squares, triangles and Xs, respectively). The 0 h regime corresponded to inoculated non-thermoregulating locusts (INTR). C-non-infected, thermoregulating locusts are indicated by filled rhombuses. (n = 30 for three biological replicates). ANOVA on mortality on day 20 is followed by LSD (different letters indicate significant differences).
Fig 5.
Effect of thermoregulation onset on mortality of infected locusts.
Mortality of Locusta migratoria manilensis inoculated with Beauveria bassiana (106 spores/5th instar nymph) and exposed to various thermoregulation durations (0 h, 24 h and 48 h post-inoculation are indicated by filled squares, triangles, circles and Xs, respectively). The 0 h regime corresponds to infected locusts allowed to thermoregulate immediately after infection. INTR indicates inoculated and non-thermoregulating locusts. C indicates non-thermoregulating and non-infected control locusts. n = 25 insects per treatment. ANOVA on mortality at day 10 is followed by LSD (different letters indicate significant differences).
Fig 6.
Impact of early termination of thermoregulation on the survival of infected locusts.
The mortality of Locusta migratoria manilensis inoculated with Beauveria bassiana (106 spores/5th instar nymph) after early termination of thermoregulation. Insects were initially allowed to thermoregulate (0, 24, or 48 h post inoculation, with INTR as a control). The opportunity to thermoregulate was ended after 10 days (so that day 11 became day 1 of post-interuption, as labeled in the figure). C represents non-thermoregulating and non-infected control locusts. INTR represents inoculated and non-thermoregulating locusts, with n = 25 insects per treatment. ANOVA was conducted on mortality at day 10 followed by LSD (different letters indicate significant differences).
Fig 7.
Mean haemocyte concentrations in haemolymph samples of Locusta migratoria manilensis inoculated with Beauveria bassiana (3×105 spores/5th instar nymph) at different days post-infection. CNTR, control non-thermoregulating insects; CTR, control thermoregulating insects; INTR, infected non-thermoregulating insects; ITR, infected thermoregulating insects. Data are given as concentration (means ± SE). 10–15 insects were infected per treatment and per interval. Different letters indicate significant differences.
Fig 8.
Mean blastospore concentrations in haemolymph samples of Locusta migratoria manilensis inoculated with Beauveria bassiana (3×105 spores/5th instar nymph), at different numbers of days post-infection. INTR, infected non-thermoregulating insects; ITR, infected thermoregulating insects. Data are given as concentration (means ± SE). 10–15 insects were infected per treatment and per interval.
Fig 9.
In vivo phagocytic activity of Locusta migratoria manilensis inoculated with Beauveria bassiana (3×105 spores/5th instar nymph) and injected with FITC-labelled silica beads at various days post-infection. CNTR means control non-thermoregulating insects; CTR, control thermoregulating insects; INTR, infected non-thermoregulating insects; and ITR, infected thermoregulating insects. Data are given as percentages (means ± SE). 8–10 insects were used per treatment and per interval. Different letters indicate significant differences.