Investment in immune function under chronic and acute immune challenge in an insect

Abstract

Summary In this paper we investigate the relationship between the chronic burden of mid‐gut parasites (eugregarine trophozooites) and the effect of an acute haemolymph challenge (a nylon insert) on two important insect immune effector systems (phenol oxidase (PO) and the encapsulation response) in a field‐population of damselflies. PO levels in the haemolymph, and the magnitude of the encapsulation response were maintained, regardless of chronic and subsequent acute experimental immune challenges. The maintenance of these effector systems is therefore probably an important life‐history requirement in these damselflies. Investment in mid‐gut PO levels was significantly negatively related to the animal's chronic parasite burden after an acute experimental challenge in the haemolymph, suggesting that maintaining PO levels across two physiological compartments (haemolymph and mid‐gut) is costly. The results suggest that the immune effector system activity in different physiological compartments in an insect's body is affected by chronic parasite burdens in the face of the demands imposed by an acute immune insult.

Sex differences in immune defenses and response to parasitism in monarch butterflies

“…Together, these findings suggest that (1) production of hemocytes increased in the presence of a debilitating parasite, and (2) males and females may differ in baseline hemocyte production and response to infection. Previous work has demonstrated that insects can show increased expression of immune defenses, including hemocyte concentrations, following acute challenges by foreign materials (Freitak et al 2003;Robb and Forbes 2006) although patterns vary with insect species and the specific immune effector traits assayed (Siva-Jothy et al 2001;Yourth et al 2002;Adamo 2004;Chernysh et al 2004;Armitage and Siva-Jothy 2005). The increased hemocyte production observed here indicates that this immune effector trait might be an inducible (rather than constitutive) defense under some circumstances.…”

Effects of age and gender on immune function of dragonflies (Odonata, Lestidae) from a wild population

“…It is noteworthy that only Nigam et al (1997) show that high PO expression per se indicates higher immunocompetence; otherwise this can only be concluded indirectly from studies like Gorman et al (1996) and Siva-Jothy et al (2001). To demonstrate that higher PO activity in females is advantageous, in future experiments higher female survival should be established in infections where PO activity is used as a defense mechanism.…”

Immune Suppression and the Cost of Reproduction in the Ground Cricket, Allonemobius Socius

“…(2) Phenoloxidase activity provided a measure of the hemolymph-bound enzyme, prophenoloxidase, which is also a key component of invertebrate innate immunity (Sö derhäll and Cerenius 1998;Siva-Jothy et al 2001;Rolf and Siva-Jothy 2002). (3) Lytic activity provided a measure of another hemolymph-bound enzyme, lysozyme, which provides a general defense against bacterial insults (Rantala and Kortet 2003).…”

“…(4) Encapsulation ability provided a measure of the degree to which a macroscopic invading body (e.g., parasitoid egg) is engulfed by hemocytes and melanized, thereby killing the invader. Encapsulation requires the coordination of several cell-mediated and humoral immune components (Ratcliff 1993) and therefore provides a simple and reliable assay as to the direct effectiveness of an individual's immune system (Siva-Jothy et al 2001).…”