Effects of temperature on the adults and progeny of the predaceous mite Lasioseius japonicus (Acari: Blattisociidae) fed on the cereal mite Tyrophagus putrescentiae (Acari: Acaridae)

Effect of temperature on functional response of Blattisocius mali (Acari: Blattisociidae) preying on the acarid mite Tyrophagus putrescentiae

Climate warming significantly impacts soil temperature and moisture, leading to changes in the activity of soil mites and the foraging behaviour of edaphic predatory mites. The current research aimed to investigate the effect of temperature on the functional response of the predatory soil mite Blattisocius mali Oudemans preying on either eggs or males of the mould mite Tyrophagus putrescentiae Schrank. To analyze the functional response type, the generalized functional response equation of Real was used while the functional response parameters were determined using Roger, Hassell, and Cabello et al. models. Female adult B. mali displayed Type III and Type II functional responses when preying on eggs and males, respectively across all tested temperatures, ranging between 10 °C and 35 °C. The handling time of B. mali was shorter at higher temperatures, 25 °C, 30 °C, and 35 °C when preying on either eggs or males. In contrast, the potential for prey mortality, the attack rate, and the functional response ratio were higher at higher temperatures indicating higher efficiency of B. mali at higher temperatures. The temperature strongly impacted predators' efficiency, as accelerated predator action under warming increased prey consumption. However, functional response type did not change with warmer temperatures but varied with changing prey stages from egg to male.

Temperature-induced effects on development, reproduction, and predation of Harmonia axyridis fed on first instar larvae Spodoptera litura

Since metabolism, survival, and reproduction in hexapods are closely related to temperatures; changes in the mean and variance of temperature are major aspects of global climate change. In the typical context of biological control, understanding how predator-prey systems are impacted under thermal conditions can make pest control more effective and resilient. With this view, this study investigated temperature-mediated development and predation parameters of the predator Harmonia axyridis against the potential prey Spodoptera litura. The age-stage, two-sex life table of the predator was constructed at four temperatures (i.e. 15, 20, 25, and 30°C) by feeding on the first instar larvae of S. litura. Our results showed that the mean generation time (T) decreased but the intrinsic rate of increase (r) and the finite rate of increase (λ) increased with increased temperature. The mean duration of the total preadult stage decreased with higher temperatures. The T and r were 70.47 d and 0.0769 d-1 at 15°C; 58.41 d and 0.0958 d-1 at 20°C; 38.71 d and 0.1526 d-1 at 25°C; and 29.59 d and 0.1822 d-1 at 30°C, respectively. The highest net reproductive rate (R0) and fecundity were obtained at 25°C. The highest λ (1.1998 d-1) and lowest T (29.59 d) were obtained at 30°C, whereas the maximum net predation rate (C0) was at 25°C. Total population and predation rates projections were the highest at 30°C. Based on these findings, we anticipate that biological control strategies for this predator release against S. litura should be attuned to warming scenarios to achieve better biocontrol functions.

Ectoparasites of European hedgehogs (Erinaceus europaeus) in Germany and their health impact

BACKGROUND

The European hedgehog (Erinaceus europaeus) is known for high levels of ectoparasitism that not only represents a health risk for the animals themselves, but also for pet animals and humans as hedgehogs are frequently taken into human care. In the present study, patterns of ectoparasite infestation were assessed in hedgehogs taken into care at northern German animal rehabilitation centres.

METHODS

Ectoparasites (ticks, fleas and mites) of 498 hedgehogs were collected over a period of 3 years from July 2018 to May 2021. Species were identified based on morphological characteristics and also via amplification and sequencing of the partial cytochrome c oxidase subunit 2 (COX-2) gene for fleas of the family Ceratophyllidae. Seasonal changes in infestation patterns as well as correlations with animal age, body weight and health status were assessed using generalised linear models.

RESULTS

Infestation with ticks, fleas and mites occurred throughout the year. Overall, 86.5% (431/498) of the examined hedgehogs were infested with ticks, 91.4% (455/498) with fleas and 17.7% (88/498) with mites. Ixodes ricinus and Ixodes hexagonus/Ixodes canisuga were the most common tick species detected, with the additional occurrence of one Ixodes frontalis. Significant seasonal changes were observed for I. ricinus, but not for I. hexagonus/I. canisuga. Additionally, I. ricinus nymph prevalence declined significantly as of 2020, probably as a consequence of the climate change-related drought as of 2018. In hedgehogs with flea infestations, Archaeopsylla erinacei, Ceratophyllus sciurorum, Nosopsyllus fasciatus and Ctenocephalides felis were identified. In all cases of mite infestation, Caparinia tripilis was detected, in addition to specimens of the family Macronyssidae and free-living mites of the family Acaridae. Statistical analyses showed correlations regarding the factors month, year, body weight and age, but no correlation was evident regarding the health status of the animals.

CONCLUSIONS

With a detected infestation rate of 98.6%, almost all of the examined hedgehogs were infested with at least one ectoparasite species. The seasonal activity patterns of the different ectoparasite species together with the complex annual cycle of hedgehogs lead to different seasonal patterns in ectoparasite prevalence and infestation intensities. Due to the risk of transmission of zoonotic pathogens as well as the possible negative impact on the host itself, hedgehogs should be treated against ectoparasites when taken into care facilities.