An explanation for courting traits is that they convey information about the bearer's condition to conspecifics, more specifically immune ability. Here we test a series of immune-based assumptions in the territorial damselfly Hetaerina americana, whose males bear wing pigmentation patterns, which are maintained via male-male competition. H. americana males emerge and take some time to mature sexually, after which, depending on their fat reserves, may start defending territories where females arrive at for copulation. Territorial males are eventually defeated and lose their territories. This loss is a consequence of a reduction in muscular fat reserves. We tested whether: (a) territorial males had more pigmented wings, more intense melaninebased immune response (encapsulation response to a nylon filament implant) and higher fat reserves than nonterritorial males; (b) pigmentation is related to immunity and fat reserves; (c) the immune response held constant in two different episodes (3 days between each) in the same male during territorial tenure; and (d) immune response and fat reserves decreased after experimentally simulated fighting event. Our results agree with current views of immune ability and courting traits: (1) territorial males had more wing pigmentation, higher immune responses and fat reserves than non-territorial males; (2) pigmentation was also correlated with immunity and fat reserves; and (3) immune response was similarly intense in the two episodes during territorial tenure. However, this response and fat reserves were considerably lower after fighting compared to that of territorial males and non-territorial males. Our work points out a link between fat reserves and immune ability which agree with previous studies in insects. Given, however, that in this species the use of wing pigmentation via male-male competition is more likely to provide information about current fat reserves than immunity, it is suggested that immune ability is only indirectly selected and may not be the information that pigmentation would convey to conspecifics.

Abstract. 1. Immune priming refers to improved protection of the host after a second encounter with the same parasite or pathogen. This phenomenon is similar to that of adaptive immunity in vertebrates.2. There is evidence to suggest that this improved protection can be species/ strain-specific and can protect organisms for a lifetime. These two attributes, along with a biphasic immune response, are essential characteristics of immune priming and form the basis for the effectiveness of resistance to parasites and pathogens.3. This paper considers the effect of immune priming within and across generations, the influence of a heterologous challenge during immune priming and the importance of testing the immune response with natural pathogens.4. The analysis presented takes into account the multifaceted nature of the invertebrate immune response. The lack of evidence suggesting that the bacterial microbiome plays a complementary role in the immune priming outcome is discussed.5. Finally, the cost of immune priming is explored. This is a poorly investigated issue, which could help to explain why there is a paucity of evidence in support of immune priming.

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Here we report the presence of the entomopathogenic nematode Rhabditis (Rhabditoides) regina affecting white grubs (Phyllophaga sp. and Anomala sp.) in Mexico and R. regina-associated bacteria. Bioassays were performed to test the entomopathogenic capacity of dauer and L2 and L3 (combined) larval stages. Furthermore, we determined the diversity of bacteria from laboratory nematodes cultivated for 2 years (dauer and L2-L3 larvae) and from field nematodes (dauer and L2-L3 larvae) in addition to the virulence in Galleria mellonella larvae of some bacterial species from both laboratory and field nematodes. Dauer and non-dauer larvae of R. regina killed G. mellonella. Bacteria such as Serratia sp. (isolated from field nematodes) and Klebsiella sp. (isolated from larvae of laboratory and field nematodes) may explain R. regina entomopathogenic capabilities. Different bacteria were found in nematodes after subculturing in the laboratory suggesting that R. regina may acquire bacteria in different environments. However, there were some consistently found bacteria from laboratory and field nematodes such as Pseudochrobactrum sp., Comamonas sp., Alcaligenes sp., Klebsiella sp., Acinetobacter sp., and Leucobacter sp. that may constitute the nematode microbiome. Results showed that some bacteria contributing to entomopathogenicity may be lost in the laboratory representing a disadvantage when nematodes are cultivated to be used for biological control.