Parasitism effects on P. perpusilla nymphs
Mortality as nymphs, intermediate forms or weak adults
Significant differences were observed in the nymphal mortality when nymphs of various ages were offered to the parasitoid (F = 1485.0, df = 5, 24, p < 0.0001). The mortality was 100% in the first nymphal stage, followed by the second (94.00 ± 1.00%), third (75.00 ± 1.58%), fifth (41.00 ± 1.29%) and fourth stage (38.00 ± 1.22%) nymphs (Fig. 1). The mortality as intermediate forms was 51.0, 18.0, 11.0 and 3.0% in fourth, third, fifth and second nymphal stages, respectively (F = 126.76, df = 4, 20, p < 0.0001). After completing the nymphal period, the death in parasitized nymphs as weak adults was also observed (F = 59.84, df = 4, 20, p < 0.0001). The percentage mortality as weak adult was 30.0, 11.0, 7.0 and 3.0% in fifth, fourth, third and second nymphal stages, respectively (Fig. 1).
The longevity of nymphs parasitized in the later stages (third, fourth and fifth) was prolonged significantly than in un-parasitized nymphs (F = 269.72; df = 4, 20; p < 0.0001) and the highest prolongation (+ 8.11 days) being in the fourth parasitized nymphs. While the developmental period of nymphs parasitized in the second stage was comparatively shorter (− 8.32 days) as against un-parasitized nymphs (Table 1).
Survival as normal adults
None of the nymph parasitized at the first, second, third, and fourth stage survived as normal adult. They died as weak nymphs, nymph-adult intermediates, or weak adults. In case of 5th parasitized nymphs, 18.00 ± 1.29% adults were normal. While 100% survival was observed in un-parasitized nymphs (F = 8619.74, df = 4, 20, p < 0.0001; Fig. 2).
Longevity of surviving host adults
Irrespective of host stage, females survived for a longer duration as compared to males (Fig. 3). Significantly lower longevity was found in adult females from parasitized 5th nymphal stage than on un-parasitized nymphs (t = 12.94, p = 0.0001). However, the longevity of adult males from parasitized 5th nymphal stage did not differ significantly from un-parasitized ones (t = 1.68, p = 0.0659).
Parasitism effects on P. perpusilla adults
When male and female pyrilla adults were offered to the parasitoid, significant differences were observed in mortality of parasitized and un-parasitized adults for both the sexes (for male, t = 94.00; p < 0.0001 and for female, t = 56.92; p < 0.0001). The parasitism resulted in 94.0 and 90.0% mortality of adult males and adult females, respectively. However, no mortality was recorded in un-parasitized adults for both the sexes (Fig. 4).
Irrespective of host sex, parasitized host female survived for a longer duration than the parasitized males. However, the parasitism prolonged the longevity of surviving host adults significantly for both sexes (for male, t = 12.40; p < 0.0001 and for female, t = 7.23; p < 0.0001). The longevity of parasitized males was significantly longer (+ 7.15 days) than the un-parasitized males. Similarly, parasitized females survived for a longer period (+ 5.26 days) as against un-parasitized ones (Table 2).