Effects of endophytic B. bassiana on B. tabaci performance
To determine whether B. bassiana treated tomatoes affect the performance of B. tabaci, we compared survival, and fecundity of adult female on root irrigated tomatoes with B. bassiana, local leaf sprayed tomatoes with B. bassiana and control tomatoes. After 3 days of feeding, we found no differences in survival rate of adult females B. tabaci on B. bassiana root irrigation tomatoes, B. bassiana local leaf spray tomatoes and control tomatoes (F2,21 = 0.4196, P = 0.6627) (Fig. 1a). However, the female B. tabaci feeding on the B. bassiana root irrigation tomatoes produced fewer eggs compared with the local leaf spray and control tomatoes and there were significant differences among the three treatments. (F2,21 = 43.79, P < 0.0001) (Fig. 1b). The results of 5 days after feeding were consistent with those of 3 days (Fig. 1c, 1d).
Effects of endophytic B. bassiana on survival rate and reproduction rate of B. tabaci population
The developmental duration and survival rate of tomatoes under different treatments were significantly different (Fig. 2). The time of each developmental stages of B. tabaci in the treatment group was significantly longer than that in the control group. For example, when the survival rate of female adults in the control group was close to 45%, the time was 22 days, respectively, but the treatment time of B. bassiana on tomato was 25 days. The survival rate of different developmental stages of B. tabaci in the treatment group was significantly lower than in the control group. For example, in the control group, the highest survival rates of the first-instar nymphs, the second-instar nymphs, the third-instar nymphs, the fourth-instar nymphs and female adults of B. tabaci were 89.36%, 65.96%, 65.96%, 83.69% and 62.41%, respectively. However, the survival rates of B. tabaci on the treatment group were 80.18%, 53.15%, 48.65%, 67.57% and 48.65%, respectively.
The age-specific survival rate (lx), female age-specific fecundity (fx), age-specific fecundity (mx), and age-specific maternity (lxmx) of B. tabaci were also calculated for the group-reared method (Fig. 3). At the early stages of development for B. tabaci reared on tomato colonized by B. bassiana, the survival rate (lx) curve dropped more rapidly than it did on control tomato, indicating that the mortality rate at this stage was high on treatment tomato. The female age-specific fecundity (fx) curve on on tomato colonized by B. bassiana was lower than those on control tomato. The curve of age-specific fecundity (mx) showed that reproduction began at 19.5 days and 19 days respectively on treated tomato and control tomato. However, the age-specific fecundity (mx) curve of B. tabaci on treated tomato plants was generally lower than that of control. The age-specific maternity (lxmx) and age-specific fecundity (mx) curves showed similar trends.
The age-specific life expectancy of B. tabaci on tomato colonized by B. bassiana was lower than those of the control tomato. In addition, the reproductive value of B. tabaci on tomato colonized by B. bassiana weas lower than those of the control tomato at 1‒28 days and 39.5‒49 days, but the fecundity of the treatment group was higher than that of the control at 28.5‒39 days (Fig. 4).
Effects of endophytic B. bassiana on life table parameters of B. tabaci population
The intrinsic rate of increase, the finite rate of increase and the net reproductive rate of B. tabaci on tomato colonized by B. bassiana were significantly lower than those of the control tomato, but there was no significant difference in the mean generation time (Table 1).
Table 1
Population parameters of B. tabaci on tomato plants under different treatments
Population parameter | Control | Bb252 | P |
Intrinsic rate of increase (r) (d− 1) | 0.1283 ± 0.0033 | 0.1057 ± 0.0024 | 0.005 |
Finite rate of increase (λ) (d− 1) | 1.1369 ± 0.0066 | 1.1114 ± 0.0047 | 0.005 |
Net reproductive rate (R0) (offspring) | 35.0121 ± 3.2579 | 20.5043 ± 1.3184 | 0.002 |
Mean generation time (T) (d) | 27.7053 ± 0.7249 | 28.7297 ± 1.3204 | 0.304 |
The P values in each row represent significant differences, with P < 0.05 representing significant differences between two groups. SEs were estimated by bootstrapping (100,000 replications)
Effects of endophytic B. bassiana on feeding behavior of B. tabaci
The EPG analysis showed that B. tabaci had significantly different feeding behaviors on control and B. bassiana treated tomato plants. The duration of probing, watery salivation (E1), and phloem ingestion (E2) of B. tabaci on B. bassiana root irrigation treated tomato plants was significantly shorter than that of B. tabaci on control plants (t = 2.920, df = 33, P = 0.006 and t = 4.005, df = 33, P < 0.001 and t = 11.56, df = 33, P < 0.001, respectively) (Fig. 5b, 5d, 5e). Moreover, the total duration of non-probing (np) of B. tabaci on B. bassiana root irrigation treated tomato plants were significantly longer than that of B. tabaci on control plants (t = 2.994, df = 33, P = 0.005) (Fig. 5a). However, the duration of the stylet pathway phase (C) and the duration of potential drop (intracellular puncture) (pd) did not differ between control and B. bassiana treated plants (t = 0.4287, df = 33, P = 0.6710 and t = 1.393, df = 33, P = 0.1730, respectively) (Fig. 5c, 5f).