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The effect of relative humidity on the development of the FAW egg parasitoid Telenomus remus Nixon

            By: Alice dos Reis Fortes; Aloisio Coelho Jr.; José Roberto Postali Parra

          A possible natural enemy for biological control of the Fall Armyworm, Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae), is the wasp Telenomus remus Nixon, 1937 (Hymenoptera: Platygastridae), an egg parasite used in control programs in some parts of Latin America. The efficiency of T. remus is linked to its ability to parasitize all the layers of an S. frugiperda egg mass. This gives it an advantage over parasitoids of the genus Trichogramma spp. (Hymenoptera: Trichogrammatidae), which are widely used in biological control programs but parasitize only the eggs in the surface layer of the mass.

       Among the abiotic factors that can directly influence the parasitism and biology of a parasitoid, temperature and relative humidity (RH) have been relatively well studied. The biological characteristics of T. remus reared on its natural host S. frugiperda are apparently not affected by RH. At RHs of 40%, 60% and 80%, the percentages of parasitism are 82.67%, 80.81% and 72.72% and the viabilities are 90.18%, 89.33% and 86.18%, respectively; in contrast, a sex ratio with more females is obtained at 40% RH (Pomari-Fernandes et al., 2015).

          Telenomus remus is currently being reared on its natural host S. frugiperda. However, maintaining a population of this armyworm in the laboratory for mass production is impracticable, since larval S. frugiperda cannibalize each other and must be reared individually. In search of a suitable factitious host for large-scale T. remus rearing, some investigators have evaluated Corcyra cephalonica Stainton, 1865 (Lepidoptera: Pyralidae). Tests of T. remus reared on C. cephalonica at RHs of 40%, 60% and 80% showed that the parasitoid performs best at a RH of 80%, with a parasitism capacity of 28.40%, viability of 86.18% and sex ratio of 0.85 (Pomari-Fernandes et al., 2015).
          Available data demonstrate that the RH does not affect biological parameters of T. remus over the egg-adult period, which is around 12.5 days. However, the RH may strongly affect the biological parameters of immature wasps, especially when reared on a factitious host. Temperature and RH are the abiotic factors that most influence the spatial distribution of insects; therefore, more precise studies are needed to evaluate the effect of RH on the biology of T. remus.

References used:

ALAM, M. M. Attempts at the biological control of major insect pests of maize in Barbados, W. I. Proceedings of the Caribbean Food Crops Society, v. 15, p. 127-135. 1978.

BESERRA, E. B.; PARRA, J. R. P. Biologia e parasitismo de Trichogramma atopovirilia Oatman & Platner e Trichogramma pretiosum Riley (Hymenoptera, Trichogrammatidae) em ovos de Spodoptera frugiperda (J.E. Smith) (Lepidoptera, Noctuidae). Revista Brasileira de Entomologia, v. 48, n. 1, p. 119-126, 2004.

CAVE, R. D. Biology, ecology and use in pest management of Telenomus remus. Biocontrol, v. 21, n. 1, p. 21-26, 2000.

CHAPMAN, J. W.; WILLIAMS, T.; MARTINEZ, A. M.; CISNEROS, J.; CABALLERO, P.; CAVE, R. D.; GOULSON, D. Does cannibalism in Spodoptera frugiperda (Lepidoptera: Noctuidae) reduce the risk of predation? Behavioral Ecology and Sociobiology, v. 48, p. 321–327, 2000.

FERRER, F. Biological control of agricultural insect pest in Venezuela: advances, achievements, and future perspectives. Biocontrol News and Information, v. 22, p. 67-74, 2001.

HERNÁNDEZ, D.; FERRER, F.; LINARES, B. Introducción de Telenomus remus Nixon (Hym: Scelionidae) para controlar Spodoptera frugiperda (Lep.: Noctuidae) en Yaritagua Venezuela. Agronomía Tropical, v. 39, n. 1–3, p. 45–61, 1989.

POMARI-FERNANDES, A.; QUEIROZ, A. P. de; BUENO, A. de F.; SANZOVO, A. W.; BORTOLI, S. A. de. The importance of relative humidity for Telenomus remus (Hymenoptera: Platygastridae) parasitism and development on Corcyra cephalonica (Lepidoptera: Pyralidae) and Spodoptera frugiperda (Lepidoptera: Noctuidae) eggs. Annals of the Entomological Society of America, v. 108, n. 1, p. 11–17, 2015.

QUEIROZ, A. P.; BUENO, A. de F.; POMARI-FERNANDES, A.; GRANDE, M. L. M.; BORTOLOTTO, O. C.; SILVA, D. M. da. Quality control of Telenomus remus (Hymenoptera: Platygastridae) reared on the factitious host Corcyra cephalonica (Lepidoptera: Pyralidae) for successive generations. Bulletin of Entomological Research, s.v. October, p. 1–8, 2017a.

QUEIROZ, A. P.; BUENO, A. de F.; POMARI-FERNANDES, A.; BORTOLOTTO, O. C.; MIKAMI, A. Y.; OLIVE, L. Influence of host preference, mating, and release density on the parasitism of Telenomus remus (Nixon) (Hymenoptera, Platygastridae). Revista Brasileira de Entomologia, v. 61, n. 1, p. 86–90, 2017b. 

POMARI, A. F.; BUENO, A. de F.; BUENO, R. C. O. de F.; MENEZES JUNIOR, A. de O.; FONSEA, A. C. P. F. Releasing number of Telenomus remus (Nixon) (Hymenoptera: Platygastridae) against Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) in corn, cotton and soybean. Ciência Rural, v. 43, n. 3, p. 377–382, 2013.

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Manju Thakur
Manju Thakur (@manju_ento)
18 days ago

Hi  Alice dos Reis Fortes -This is very nice research. This would help us to connect to how the climate change might effect the natural enemies abundance and activity.

Aloisio Coelho Jr.
Aloisio Coelho Jr. (@aloisiocoelho)
Reply to  Manju Thakur
5 days ago

Hi Manju, certainly, but in our case we can use these informations to improve the mass-rearing and also to understand how T. remus will spread on fields.

Manju Thakur
Manju Thakur (@manju_ento)
Reply to  Aloisio Coelho Jr.
3 days ago

 Aloisio Coelho Jr. You are right! Would be interesting to hear more updates on outcomes of your research.