Parasitoid Hymenoptera collected during the diurnal and nocturnal periods in Itumbiara, Goiás

NOTES AND COMMENTS

Parasitoid Hymenoptera collected during the diurnal and nocturnal periods in Itumbiara, Goiás

Marchiori, CH.I, ^*; Lussari, MA.^II; Rosa, DC.^II; Penteado-Dias, AM.^III

^ICentro Federal de Educação Tecnológica de Urutaí-UNED, CP 92, CEP 75650-000, Morrinhos, GO, Brazil

^IIInstituto Luterano de Ensino Superior de Itumbiara-ILES-ULBRA, Rua Beira Rio 1001, Bairrro Nova Aurora, CEP 75.500-000, Itumbiara, GO, Brazil

^IIIDepartamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Carlos – UFSCar, Rodovia Washington Luis, Km 235, CEP 13565-905, São Carlos, SP, Brazil

The insects of the order Hymenoptera form a diverse group of approximately 200,000 species (La Salle and Gauld, 1992). Thanks to these insects, great savings in pest control programs have been achieved. They are mostly parasitoid organisms and, in the Neotropical region, they have been little studied and are poorly known. Parasitoid Hymenoptera are the most important biological control agents and they are responsible for most of the economic and environmental benefits produced by biological control programs. They may provide support for biological and conservation studies. Their action on hosts increases with growth in their population and decreases with reductions in populations. The two interlinked populations fluctuate in relation to each other in such a way as to impede both abrupt increases and the extinction of the host population (Gauld and Bolton, 1988; La Salle and Gauld, 1992; Scatolini and Penteado–Dias, 1997).

Interest in biological controls has grown in various countries, as a response to the adverse effects of chemical pesticides on the environment and on biodiversity. Moreover, it has grown as a function of new international trends in agricultural production involving the utilization of alternative means that are less aggressive to the environment and which favor conservation and the sustainable use of biodiversity (Scatolini and Penteado-Dias, 1997).

The objective of this study was to investigate the frequency of occurrence of parasitoid Hymenoptera collected during the diurnal and nocturnal periods in Itumbiara, State of Goiás.

The experiment was carried out in an area of remnant forest located close to the urban perimeter of Itumbiara, Goiás, at the coordinates 18° 25' S and 49° 13' W, in an area of the southern part of the State that has great economic importance because of its agricultural and industrial activities. The climate of the region is of AW type, according to Köppen's classification (Rosa and Assunção, 1991) with dry winters and rainy summers. It is a type of savanna climate, in which the annual rainfall is more than ten times the rainfall in the driest month (which is less than 60 mm).

The insects were collected in a Malaise trap. The collecting flasks were put out at 6:00 P.M. and replaced by new ones at 7:00 A.M. every day for ten consecutive days, thus totaling 40 collections between May and August, 2005.

The parasitoids' preference for the diurnal or nocturnal period was analyzed by means of ANOVA, with a transformation of data to Ö x + 0.5 at the 5% probability level.

A total of 135 specimens of parasitoids was collected. These were distributed among seven superfamilies and sixteen families of Hymenoptera (Table 1). Chalcidoidea presented the greatest diversity of families, and this group together with Ichneumonoidea predominated in the native forest ecosystem.

Among the individuals collected, 39.3% were in the diurnal period and 60.7% in the nocturnal period (Table 1). The specimens and the parasitoid families did not present any preference for either of these two periods (F = 0.73; P > 0.39) and (F = 1.26; P > 0.24), respectively. Factors such as resource quality and availability, host density, climatic factors, floristic composition of the sampled fragment and the number of collections carried out may have influenced these results. According to Wallner (1987), not only climatic factors but also variations in resource quality and availability may cause changes in the population's abundance levels of these insects.

During the diurnal period, the family that was collected most was Ichneumonidae, accounting for 56.5% of the individuals collected (Table 1) with statistically significant predominance of this family in relation to the others (F = 9.23; P > 0.0001). This was probably due to its parasitizing efficiency: its species are parasitoids on eggs, larvae, pupae or imagos of other insects (Scatolini and Penteado-Dias, 1997; Ros-Ferré et al., 1997).

During the nocturnal period, the family that was collected most was Encyrtidae, accounting for 31.7% of the individuals collected (Table 1). Many genera of Encyrtidae present polyembryonic reproduction, with many parasitoids emerging from a single host. Several species of this family have been successfully utilized in biological control programs (Noyes, 1980; Gauld and Bolton, 1988).

These results contribute towards the knowledge of the entomofauna of parasitic Hymenoptera in the Itumbiara region in the southern part of the State of Goiás.

References

GAULD, ID. and BOLTON, B., 1988. The Hymenoptera. Oxford University Press, Oxford, 5th ed., 33p.

LA SALLE, J. and GAULD, ID., 1992. Parasitic Hymenoptera and biodiversity crisis. Redia, vol. 74, (appendix), p. 315-334.

NOYES, JS., 1980. A review of genera of Neotropical Encyrtidae (Hymenoptera: Chalcidoidea). Entomol. Ser., vol. 41, no. 3, p. 1253.

ROSA, RLSC. and ASSUNÇÃO, WL., 1991, Abordagem preliminar das condições climáticas de Uberlândia (MG). Soc. Nat., vol. 3, no. 2, p. 91-108.

ROS-FERRÉ, CSP., ALGARRA, A. and VENTURA, D., 1997. Estudio comparativo de las capturas realizadas com trampa malaise en Andorra com especila atención a los himenópteros (Hymenoptera). Rev. Aragon. Entomol., vol. 7, no. 1, p. 71-82.

SCATOLINI, D. and PENTEADO-DIAS, AM., 1997. Fauna de Braconidae (Hymenoptera) como bioindicadora do grau de preservação de duas localidades do Estado do Paraná. Revista Brasileira de Ecologia, vol. 1, no. 1, p.84-87.

WALLNER, WE, 1987. Factors affecting insect population dynamics: differences between outbreak and non-outbreak species. Annu. Rev. Entomol., vol. 32, p. 317-340.

Received November 10, 2006

Accepted December 11, 2006

Distributed August 31, 2007

Publication Dates

• Publication in this collection
  05 Dec 2007
• Date of issue
  Aug 2007