Biological Characteristics and Thermal Requirements of the Biological Control Agent Telenomus remus (Hymenoptera: Platygastridae) Reared on Eggs of Different Species of the Genus Spodoptera (Lepidoptera: Noctuidae)

Abstract

The biological characteristics of Telenomus remus Nixon, 1937 (Hymenoptera: Platygastridae) on eggs of Spodoptera albula (Walker, 1857); S. cosmioides Walker 1858, S. eridania (Cramer, 1782); and S. frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) were evaluated under different temperatures (19, 22, 25, 28, 31, and 34°C ± 1°C). The duration of the T. remus egg-to-adult period on eggs of all four Spodoptera species and the longevity of adults of T. remus were both inversely proportional to the increase in temperature. Parasitoid emergence was higher than 80% at temperatures from 19 to 28°C when the parasitoid was reared on eggs of S. eridania and S. frugiperda. Differently, when the parasitoid was reared on eggs of S. albula and S. cosmioides, T. remus emergence at rates of 80% or higher just occurred from 22 to 25°C and at 22°C, respectively. At 34°C, this parameter was lower than 30% for T. remus reared in all hosts. The sex ratio was 64–86% females, except for T. remus in S. cosmioides eggs at 34°C, in which temperature it was 39%. The estimated thermal requirements of T. remus, for the thermal constant (K) and the base temperature (Tbase), were: 125.39 DD and 15.139°C; 125.56 DD and 14.912°C; 142.98 DD and 14.197°C; and 149.16 DD and 13.846°C, for S. cosmioides, S. frugiperda, S. albula, and S. eridania, respectively. In general, T. remus showed good parasitism potential on all the hosts, although eggs of S. frugiperda, S. eridania, and S. albula proved to be the most suitable for mass rearing of T. remus in the laboratory. Eggs of S. cosmioides are less suitable because of the lower parasitoid emergence observed at most of the temperatures with exception of 22°C.

Biological parameters and parasitism capacity of Telenomus remus Nixon (Hymenoptera: Platygastridae) reared on natural and factitious hosts for successive generations

“…The number of parasitized S. frugiperda eggs in 24 h and the lifetime parasitism indicates a parasitism increase (recovery) after the decrease observed in the first 24 h. It is also important to observe that this noted lifetime parasitism is also similar those found when the parasitoid was reared on eggs of S. frugiperda reported in previous work (Pomari et al, 2012). Therefore, even though it might be necessary to release a higher number of T. remus when the parasitoid is from factitious host, this laboratory-produced parasitoid, reared on C. cephalonica eggs, did not lose its capacity to control S. frugiperda eggs.…”

“…Most T. remus egg-adult periods in this study did not differ more than 2 days apart, indicating that these biological parameter is not affected over the different T. remus generations on C. cephalonica eggs. Moreover, similar egg-adult period (days) had been reported when T. remus parasitized S. frugiperda eggs (Bueno et al, 2008;Pomari et al, 2012). This is a clear indication that T. remus is adapted to parasitized C. cephalonica eggs.…”

“…In this context, all tested generations supported more than 50% females indicating that the use of egg parasitoid C. cephalonica as factitious host in massive rearing does not affect the development of T. remus females. Additionally, the percentages of females obtained were similar to those observed for the host establishment and others of the same genus (Pomari et al, 2012). Thus, the smaller size of the C. cephalonica eggs in relation to the preferred hosts did not influence this biological parameter.…”

“…This parameter is dependent on different biotic and abiotic factors (Pomari et al, 2012). Nutritional requirements from T. remus immature development determines the need for a longer or shorter period of development.…”

“…The experiment was conducted in a completely randomized design with five treatments (T. remus reared on eggs of C. cephalonica for different generations -F0, F8, F13, and F19 and T. remus reared on eggs of S. frugiperda as control) and four replicates (each replicate consisting of five individualized females) in a climatic chamber, set at temperature of 25±2°C, relative humidity of 80±10% and photoperiod of 14/10 h (L/D), according to the methodology described by Pomari et al (2012) similarly to the experiment previously described. Treatments were females of T. remus reared on eggs of C. cephalonica for five different generations (F5, F6, F8, F13, and F19) exposed to parasitism for 24 h on S. frugiperda eggs.…”