Copidosoma floridanum

Pacheco, Henry Murillo, Vanlaerhoven, Sherah & Garcia, M. Angeles Marcos, 2021, Host suitability of Trichoplusia ni and Chrysodeixis chalcites (Lepidoptera: Noctuidae) for native and nonnative parasitoids expanding their host range, The Canadian Entomologist 153 (2), pp. 137-149 : 143

Copidosoma floridanum

Copidosoma floridanum could not develop on C. chalcites even though on additional replicates to the trial we confirmed that, during parasitism, eggs were oviposited inside host eggs. The trial on C. chalcites was repeated an additional three times (the last two times using individuals from new specimens collected from tomato fields), and parasitoid development was always unsuccessful. On T. ni as host, the mean (± SE) success of C. floridanum was 24.5 ± 2.88 out of 50 larvae, its mean brood size was 1478.05 ± 20.25 parasitoids per larvae (range: 761–2037), and its development time from oviposition to adult emergence was 33.44 ± 0.14 days, from oviposition to cocoon formation was 21.81 ± 0.13 days, and from cocoon to adult emergence was 11.68 ± 0.06 days.

Host mortality on parasitised hosts (T. ni = 4.40 ± 1.02 dead larvae; C. chalcites = 1.40 ± 0.37 dead larvae) was similar (T. ni: U = 49.00, P = 0.971; C. chalcites : F 1,18 = 1.301, P = 0.269) to their respective nonparasitised hosts (T. ni = 3.70 ± 0.80 dead larvae; C. chalcites = 0.90 ± 0.23 dead larvae). The host success was also similar (T. ni: F 1,18 = 0.542, P = 0.471; C. chalcites : F 1,18 = 0.746, P = 0.399) between parasitised (T. ni = 35.80 ± 2.98 larvae; C. chalcites = 32.10 ± 2.32 larvae) and nonparasitised hosts (T. ni = 33.10 ± 2.14 larvae; C. chalcites = 29.10 ± 2.58 larvae). Host mortality was higher in T. ni than in C. chalcites , host success was lower in T. ni than in C. chalcites and was similar between parasitised hosts (F 1,18 = 7.584, P = 0.018; F 1,18 = 47.335, P <0.001; F 1,18 = 0.959, P = 0.340, respectively; Fig. 4 ).

The development times from oviposition to pupa formation and from pupa to adult emergence were similar for hosts that developed into moths from parasitised T. ni and from nonparasitised T. ni eggs, but the time from egg to adult emergence was longer for those developing from parasitised hosts (U = 8748.50, P = 0.076; U = 10 467.50, P = 0.615; U = 11 793.00, P = 0.028, respectively; Fig. 5 ). The times from oviposition to pupa formation and from oviposition to adult emergence were longer for hosts that developed into moths from parasitised C. chalcites than for those developing from nonparasitised eggs, but the time from pupa to adult emergence did not differ significantly (U = 62 164.00, P <0.001; U = 61 545.50, P <0.001; U = 43 863.00, P = 0.404, respectively; Fig. 5 ).

The development times from oviposition to pupa formation, from pupa to adult emergence, and from oviposition to adult emergence were shorter for hosts that developed into moths from parasitised T. ni than the development times for parasitised C. chalcites (U = 20 287.00, P <0.001; U = 16 150.50, P <0.001; U = 20 252.50, P <0.001, respectively; Fig. 5 ). Development times from oviposition to pupa formation, from pupa to adult emergence, and from oviposition to adult emergence were shorter for hosts that developed into moths from nonparasitised T. ni than for nonparasitised C. chalcites (U = 1834.00, P <0.001; U = 67 703.50, P <0.001; U = 81 246.00, P <0.001, respectively; Fig. 5 ).

Figures

Fig. 4. Suitability parameters of hosts Trichoplusia ni and Chrysodeixis chalcites parasitised by Copidosoma floridanum. Host mortality is expressed as the number of hosts that died after parasitism without developing into moths or parasitoids. The host success is measured as the number of hosts that develop into adult moths, whether the host was parasitised or not. Sample size = 50; replicates = 10. Notes: Means (±SE) with the same letter are not significantly different (P> 0.05). Parameters were analysed using ANOVA for each variable response between host species separately.

Fig. 5. Development times for hosts Trichoplusia ni and Chrysodeixis chalcites that survived parasitism by Copidosoma floridanum and for nonparasitised hosts. White: days from oviposition to pupa formation; light grey: days from pupa to adult emergence; dark grey: days from oviposition to adult emergence. Letters outside parentheses indicate a comparison between host species inside each group (parasitised or nonparasitised). Letters inside parentheses indicate a comparison between parasitised and nonparasitised within host species.Means (±SE) with the same letter are not significantly different (P> 0.05). Parameters were analysed using Mann–Whitney U tests for independent samples by developmental parameters separately, as indicated above for letters outside and inside parentheses.