Do parasitoid density and host age affect the parasitism of Palmistichus elaeisis (Hymenoptera: Eulophidae)?

Abstract

The incidence of lepidopteran defoliants is one of the environmental factors that regulate the productivity of cultivated forests. The parasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae) has significant importance for its efficiency in the parasitism of pupae of these Lepidoptera. The objective of this study was to evaluate the development and reproduction of P. elaeisis in different densities of pupae of Spodoptera frugiperda (Lepidoptera: Noctuidae) at different ages. Pupae of 24, 48, 72 and 96 hours were exposed at densities of 1:1, 4:1, 10:1, 19:1, 31:1 and 46:1 parasitoids/host, respectively. The parasitoids remained in contact with the pupae for 72 hours in 500 mL plastic pots, conditioned in an air-conditioned room, with temperature of 25 ± 2°C, relative humidity of 70 ± 10% and photoperiod of 12 hours. It was concluded that the density of 10:1 presented great results of parasitism, and further increase of density was not needed. Pupae of 24 and 48 hours had a higher percentage of emergence. Biological variables were affected neither by parasitoid densities nor by host age.

Palmistichus elaeisis (Hymenoptera: Eulophidae) rearing in Tenebrio molitor (Coleoptera: Tenebrionidae) submitted to different diets*

“…A shorter cycle was reported for this parasitoid in pupae of T. molitor (23.42 ± 0,18 days) with the parasitoid/host density 4:1 (ZANUNCIO et al, 2008). There is a negative correlation between the increase in the number of parasitoid females per host and the length of the life cycle of P. elaeisis, since the immature competition for nutrients reduces the development time (PASTORI et al, 2012;MARTINS et al, 2019). This was also observed by exposing five densities of Melittobia digitata Dahms, 1984 (Hymenoptera: Eulophidae) per pupa of Neobellieria bullata (Parker, 1916) (Diptera: Sarcophagidae) (SILVA-TORRES;MATTHEWS, 2003).…”

“…These results demonstrate that the host species can influence the period of development of P. elaeisis. The density of parasitoids can also affect the development cycle of P. elaeisis (PASTORI et al, 2008;MARTINS et al, 2019). A shorter cycle was reported for this parasitoid in pupae of T. molitor (23.42 ± 0,18 days) with the parasitoid/host density 4:1 (ZANUNCIO et al, 2008).…”

“…Parasitoids can control populations of insect pests and stand out as one of the main groups of natural enemies. Several species of parasitoids are efficient and have been studied to be used in applied biological control programs (CRUZ et al, 2017;MARTINS et al, 2019).…”

“…Palmistichus elaeisis can parasitize pupae from several alternative hosts (BITTENCOURT; BERTI FILHO, 1999;PEREIRA et al, 2009;ZANUNCIO et al, 2008;RODRÍGUEZ-DIMATÉ et al, 2016;MARTINS et al, 2019). The development of research to maximize its production in the laboratory and allow the development of applied biological control programs is important, but it is necessary to establish low-cost and easy-to-maintain methods that provide adequate nutrition to this species (PEREIRA et al, 2010).…”

“…Size, age, nutritional quality, mechanical resistance and immunological response to natural enemies' aspects must be considered when selecting the alternative host (BRODEUR; BOIVIN, 2004;MARTINS et al, 2019).…”