Prevalence of the symbiont Cardinium in Culicoides (Diptera: Ceratopogonidae) vector species is associated with land surface temperature

Abstract

Prevalence of infection by bacterial symbionts may reflect their interactions with the host and has been shown to be correlated with environmental factors. Yet, it is still unclear whether infection by symbionts is determined by environmental factors affecting the early or imago stage of the host. Here, we identified and localized the symbiont Candidatus Cardinium hertigii (Bacteroidetes) in sympatric Culicoides biting midge species, examined its abundance, and studied its association with environmental factors. The prevalence of adult infection differed, with 50.7% from C. imicola, 31.4% from C. oxystoma, and 0% from C. schultzei gp., although phylogenetic analyses showed that Cardinium in these species is almost identical. In addition, prevalence of infection differed between climate regions, with lowest prevalence in the arid region and highest prevalence in the Mediterranean region. Multivariate linear regression analysis of Cardinium prevalence together with climatic and satellite imagery data-derived environmental variables revealed that infection prevalence is significantly associated with land surface temperature and explained up to 89.7% of infection prevalence variability. These findings suggest that the observed variation of Cardinium infection of the imago stage of Culicoides may be influenced by environmental conditions during the latter's early developmental stages.

Detection of Low-Level Cardinium and Wolbachia Infections in Culicoides

“…Recent studies have identified Wolbachia and Cardinium in Culicoides species collected in Japan, Israel, and the United Kingdom. These studies used conventional PCR assays to reveal a relatively low prevalence of both Wolbachia (1/34) and Cardinium (8/34) (13)(14)(15). In the present study, 20 species of Culicoides, collected predominately in southeastern Australia, were screened for the presence of these endosymbionts.…”

“…Screening studies conducted using conventional PCR assays detected Wolbachia DNA in a single Culicoides paraflavescens individual in Japan (13). "Candidatus Cardinium hertigii" (Bacteroidetes), another bacterial endosymbiont which also has a range of influences on its host insect, has been detected in four Culicoides species in Japan, two in Israel, and two in the United Kingdom (13)(14)(15). Endosymbiotic diversity in Australian Culicoides species has not been investigated previously, nor has a comparative analysis of Cardinium divergence in different Culicoides species from diverse geographical locations been reported.…”

Assessment of Survival and Body Size Variation of Culicoides imicola (Diptera: Ceratopogonidae) as Functions of “Candidatus Cardinium” (Bacteroidetes) Infection Status

“…Dead midges were removed and kept in absolute ethanol at 4°C until their identity and infection status were assessed individually as described above. Individual midges were subjected to DNA extraction and specific "Candidatus Cardinium" PCR detection as described by Morag et al (7). Under optimal conditions and under starvation, experiments were repeated three times.…”

Modeling insect population fluctuations with satellite land surface temperature

“…Accuracy in temperature measurements is important for applying integrated pest management (IPM) in both forest and agricultural settings (e.g., Fand et al, 2014;Faye et al, 2014), for exploring the possible effects of global warming on ecosystems and organisms (e.g., Logan et al, 2004;Gutierrez et al, 2009;Ponti et al, 2009) and for developing strategies for the management of vector-borne diseases of humans and animals over large geographic areas (e.g., Rogers et al, 1996;Gilioli and Mariani, 2011;Amek et al, 2012;Chen and Hsieh, 2012). Recently, land surface temperature (LST) data derived from satellites have been proposed as a possible source of temperature data to be fed into insect population models and used to explore ecological and environmental questions (Carbajal de la Fuente et al, 2009;Coops et al, 2009;Chuang et al, 2012;Lensky and Dayan, 2011;Morag et al, 2012;Steinman et al, 2012;Blum et al, 2013;Aharonson-Raz et al, 2014). Lensky and Dayan (2011) used LST data to investigate the variability in the developmental rate of an agricultural pest (Heliothis sp.)…”