Hemocyte Responses of the Colorado Potato Beetle,Leptinotarsa decemlineata, and the Greater Wax Moth,Galleria mellonella, to the Entomopathogenic Nematodes,Steinernema feltiaeandHeterorhabditis bacteriophora

Abstract

Hemocyte encapsulation reactions of infective juveniles of two Iranian isolates of the entomopathogenic nematodes, Heterorhabditis bacteriophora Poinar (Rhabditina: Heterorhabditidae) and Steinernema feltiae Filipjev (Tylenchina: Steinernematidae), were compared in the economic pest Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), and the greater wax moth, Galleria mellonella L. (Lepidoptera: Pyralidae). The former was a more responsive host than the latter and the hemocyte responses occurred sooner and more extensively. Complete encapsulation of some of the nematodes occurred by 4 h post injection for H. bacteriophora in both L. decemlineata and G. mellonella, and by 2 h pi for S. feltiae in L. decemlineata. The percentage of encapsulation from 24 h to 72 h pi in L. decemlineata was 86.2% for S. feltiae and 39% for H. bacteriophora. In G. mellonella there were no encapsulation or melanization responses against S. feltiae, whereas when H. bacteriophora was encapsulated and melanized (16.7%) the encapsulation level was lower than in L. decemlineata. This study may contribute to effectively selecting entomopathogenic nematode species active against significant economic pests based on the latter's cellular immune response.

Variation in the Susceptibility of Drosophila to Different Entomopathogenic Nematodes

“…Melanization is a cellular immune response of arthropods that results in melanin production at the wound site and that contributes to pathogen killing and wound healing (11,50). Previous studies have shown that EPN infection of some insects results in rapid melanization and encapsulation of IJs although in permissive hosts IJs can escape the capsule and kill the insect (51)(52)(53). Both Xenorhabdus and Photorhabdus produce specific inhibitors of phospholipase A 2 , a key component of the melanization and encapsulation reactions, suggesting that the bacterial endosymbionts of EPNs promote nematode survival by suppressing these reactions (54,55).…”

“…Studies of larger insects, such as the Japanese beetle Popillia japonica, the house cricket Acheta domesticus, and the Colorado potato beetle Leptinotarsa decemlineata, have suggested that differences in virulence among EPNs can be attributed to differences in the abilities of EPNs to infect different hosts as well as differences in the host immune response to infection (51)(52)(53). To investigate the cause of differences in survival rates among Drosophila species exposed to different EPNs, we examined infection rates and postinfection survival rates of selected Drosophila-EPN combinations.…”

Effect of an entomopathogenic nematode,Steinernema carpocapsaeon haemocyte profile and phenoloxidase activity of the Colorado potato beetle,Leptinotarsa decemlineata

“…Cellular encapsulation of the EPNs has been reported in CPB (Armer et al, 2004;Ebrahimi, Niknam, & Dunphy, 2011;Ebrahimi, Niknam, & Lewis, 2011;Thurston et al, 1994) and, in part may decrease THC. Plasmatocytes and granulocytes are the main haemocytes involved in encapsulation response of the insects against EPNs.…”

“…Cellular encapsulation of EPNs as an immune response of different insect species has been well documented and different interactions of the bacterial, nematode and host genotypes are responsible for variable efficacy of this immune reaction (Li, Cowles, Cowles, Gaugler, & CoxFoster, 2007;Walter, Dunphy, & Mandato, 2008;Wang, Campbell, & Gaugler, 1995;Wang, Gaugler, & Cui, 1994). CPB larvae also have efficient immune responses against EPNs in which melanisation and cellular encapsulation are described (Armer, Rao, & Berry, 2004;Ebrahimi, Niknam, & Dunphy, 2011;Ebrahimi, Niknam, & Lewis, 2011;Thurston, Yule, & Dunphy, 1994). Prophenoloxidases (proPO) are the inactive form of phenoloxidases (PO) and are synthesised primarily by haemocytes, then released into plasma by cell lysis (Kanost & Gorman, 2008).…”

“…Though, both proPO system activity and cellular encapsulation are the more effective defence processes against foreign multicellular organisms, it previously was described how Steinernema feltiae is able to escape from immunological detection of the host Galleria mellonella (Lepidoptera: Pyralidae), avoiding haemocytes encapsulation and inhibiting the activity of the host proPO system (Ebrahimi, Niknam, & Dunphy, 2011;Mastore & Brivio, 2008). The majority of studies regarding the interaction between EPN and immune host system are on lepidopteran and dipteran species and few data are available regarding the huge order of Coleoptera.…”