Changes in haemolymph parameters and insect ability to respond to immune challenge during overwintering

Abstract

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Fungal ectoparasites increase winter mortality of ladybird hosts despite limited effects on their immune system

“…One possible explanation for the decrease in immune system parameters lies in the reflex bleeding method used for haemolymph sampling during autumn, which can represent a specific type of immune challenge to ladybirds [39]. Alternatively, the fact that ladybirds with lower haemolymph parameters values had a slightly lower winter survival can artificially increase average haemolymph parameters for a group of ladybirds sampled after overwintering, as was performed in R ̌erǐcha et al [16]. Although ladybird survival was not significantly affected by haemolymph parameters in the present study, there was at least a tendency toward this pattern; detailed inspection of our data indicates that individuals with the lowest preoverwintering antimicrobial activity against E. coli did not survive until spring (see also data points in figure 2c).…”

“…However, the repeatability of the method is considerably high (intraclass correlation coefficient is close to 0.9; M. R ̌erǐcha 2019, personal observation). Later, the antimicrobial activity of haemolymph against Gram-negative bacteria was measured luminometrically from frozen samples using bioluminescent E. coli K12, which contains luxABCDEamp plasmid for expression of bacterial luciferase and its substrate (for methodological details, see [16,40]). Briefly, 40 µl of haemolymph diluted in an anticoagulant buffer (100-fold dilution) were mixed in a reaction well with 120 µl of a bacteria working solution containing 100 000 bacterial cells in a phosphate buffer (pH 7).…”

“…ones, but this topic has been only rarely investigated. Food availability and quality prior to overwintering was previously identified as an important factor determining overwintering success [6,12], and the potential role of predators, parasites and pathogens has been proposed [13][14][15][16].…”

“…It should be noted that Řeřicha et al . [16] have shown that the Ha. axyridis immune system and ability to respond to bacterial infection are weakened after winter, which can also indicate increased susceptibility to other pathogens during the winter season.…”

The Influence of Daily Temperature Fluctuation on the Efficacy of Bioinsecticides on Spotted Wing Drosophila Larvae

“…Given that temperature fluctuations can influence both the behavior and physiology of both bioinsecticides and target larvae [ 20 , 21 , 25 , 26 , 27 ], in this study, we considered the effects resulting from the interaction between the two players involved in biocontrol. However, to gain an in-depth picture of their response to temperature alterations occurring in many current climate scenarios, we are investigating (work in progress) the effects of DTFs on the modulation of the host insect immune processes and the infection capability of organisms used as bioinsecticides, which is known to be key factors in the success of biocontrol [ 67 , 68 ].…”