In the monarch butterfly the juvenile hormone effect upon immune response depends on the immune marker and is sex dependent

Abstract

In insects, juvenile hormone (JH) decreases or has any effect upon the phenoloxidase (PO) activity, and favors or decreases the Antimicrobial Peptides (AMPs) expression. Although there is no information about the differential effect of such hormone, two possibilities are that it depends on (a) the immune marker recorded and (b) sexual differences. Here, three commonly used immune markers, Phenoloxidase (PO), hydrogen peroxide (H 2 O 2 ), and lytic activity, were measured 3, 6 and 24 hours after administration of methoprene (JHa, an analog of juvenile hormone) in male and female monarch butterflies (Danaus plexippus). At 3 and 6 h post-JHa administration, the PO activity increased in females but it only increased at 3 h in males, whereas H 2 O 2 levels increased only in females at 3 h. For the remaining times the JHa had a null effect on PO and H 2 O 2 . On the other hand, the JHa had a null effect for lytic activity in both sexes at 3, 6 and 24 h. To our knowledge, this is the first report of a positive effect of a JHa on PO and H 2 O 2 and suggests that this effect is sex dependent.

Sexual dimorphism in immunity across animals: a meta‐analysis

“…Mean Hedges' g (95% C.I.) for the levels of each of five moderatother hormones with sex-specific expression patterns in insects(De Loof 1998Bear & Monteiro 2013) may at times result in a female-bias in immune response (e.g Villanueva et al 2013)…”

Secondary Sexual Traits, Immune Response, Parasites, and Pathogens

“…To date, the causes of what triggers the positive, negative, or null effects remain unknown (Tian et al, 2010;Adamo, 2011;Villanueva et al, 2013). Fifth, only one study has tested the sexual dimorphism of JH upon immune response (Villanueva et al, 2013), and more studies are needed to establish how general this observation is because if JH is the mechanisms behind the signal of males immunocompetence, then this hormone should only affect males and not the females (Jacobs and Zuk, 2011). Sixth, and most importantly from the evolutionary point of view, the consequence of the relationship between JH and secondary sexual traits on direct or indirect female benefits has not been studied.…”

“…Various studies have used high doses of JH, the effect of which may be more pharmacological than physiological on the variables under study, since natural levels of this hormone are not known in many insects (Zera, 2007). Fourth, JH does not always have a negative effect on the immune response; it could even favor some immune markers (Tian et al, 2010;Villanueva et al, 2013) or might not affect other markers (Rantala et al, 2003a;Villanueva et al, 2013). To date, the causes of what triggers the positive, negative, or null effects remain unknown (Tian et al, 2010;Adamo, 2011;Villanueva et al, 2013).…”

“…Fourth, JH does not always have a negative effect on the immune response; it could even favor some immune markers (Tian et al, 2010;Villanueva et al, 2013) or might not affect other markers (Rantala et al, 2003a;Villanueva et al, 2013). To date, the causes of what triggers the positive, negative, or null effects remain unknown (Tian et al, 2010;Adamo, 2011;Villanueva et al, 2013). Fifth, only one study has tested the sexual dimorphism of JH upon immune response (Villanueva et al, 2013), and more studies are needed to establish how general this observation is because if JH is the mechanisms behind the signal of males immunocompetence, then this hormone should only affect males and not the females (Jacobs and Zuk, 2011).…”

Does juvenile hormone prompt males to oxidative stress?

“…It must be pointed out that not all of the antioxidants analyzed showed a decrease in activity in the JHa group (here, catalase and glutathione peroxidase). Similarly, in studies of the immune system, some parameters decreased while others did not (Villanueva et al, 2013). It is tempting to speculate that basal levels of catalase and glutathione peroxidase must be maintained in the different stages of H. americana to promptly respond to stressful metabolic conditions.…”