Campoletis sonorensis

Parasitoid success of C. sonorensis was similar on T. ni and C. chalcites (F 1,18 = 1.28, P = 0.273; Fig. 1). Host success and host mortality were higher amongst parasitised T. ni than amongst C. chalcites, but parasitoid cocoon mortality was lower (F 1,18 = 8.05, P = 0.011; F 1,11.38 = 25.07, P <0.001; F 1,10.61 = 12.68; P = 0.005, respectively; Fig. 1). Host mortality was higher amongst parasitised T. ni than amongst nonparasitised T. ni (F 1,18 = 7.31, P = 0.015; Means ± SE: 4.00 ± 0.73 and 1.80 ± 0.36 dead larvae, respectively), but for C. chalcites, host mortality amongst parasitised larvae was similar to that amongst nonparasitised larvae (F 1,18 = 1.16, P = 0.296; Means ± SE:

1.60 ± 0.43 and 2.20 ± 0.36 dead larvae, respectively). The host success of parasitised hosts was mostly associated with the cuticular encystment of parasitoid eggs (Vinson and Iwantsch 1980b; Namba et al. 2004). On more than 50% of the surviving parasitised hosts, host larvae were observed moving the parasitoid eggs from the insertion locations in their bodies to the ends of their bodies, then isolating the eggs in bubble-like extensions that developed on top of the hosts’ last abdominal segments.

Multinomial logistic regression indicated a difference in the interaction of host success (Wald = 17.545; df = 1; P = 0.001), host mortality (Wald = 10.995; df = 1; P = 0.001), and parasitoid cocoon mortality (Wald = 14.798; df = 1; P = 0.001) with parasitoid success between parasitised T. ni and C. chalcites by C. sonorensis . The success of C. sonorensis declined more on T. ni than on C. chalcites with the increase of host success (Coefficient = 2.577) and host mortality (Coefficient = 1.066); however, it declined less than on C. chalcites with the increase of parasitoid cocoon mortality (Coefficient = − 1.555).

The development times from oviposition to cocoon formation, cocoon to adult emergence, and oviposition to adult emergence of C. sonorensis reared on T. ni were shorter than on C. chalcites (U = 1562.50, P <0.001; U = 6567.00, P = 0.010; U = 1900.50, P <0.001, respectively; Fig. 2). The mean sex ratio was slightly female-biased on T. ni (0.48 ± 0.08) and male-biased on C. chalcites (0.66 ± 0.08), but not significantly different between them (F 1,18 = 2.65, P = 0.121).