The Fitness of Mass Rearing Food on the Establishment of Chrysopa pallens in a Banker Plant System under Fluctuating Temperature Conditions

Banker plant systems can be used to sustain a reproducing population of biological control agents (BCAs) within a crop, thus providing long-term pest suppression. The founder population of natural enemies in banker plant systems is usually mass-reared on factitious hosts. Thus, a better understanding of the population fitness and pest control performance of mass-reared BCAs in the field is crucial when developing integrated pest management (IPM) strategies. In this study, we determined the fitness of the generalist predator, Chrysopa pallens (Hemiptera: Chrysopidae) ever cultured on different food sources (i.e., mass rearing food, Corcyra cephalonica eggs, and aphid food, Megoura japonica) preying on Aphis craccivora in a banker plant system in a greenhouse based on Chi’s age-stage, two-sex life table analysis method. The life tables and predation rate parameters of C. pallens were not significantly different between both treatments under fluctuating temperature conditions. Corcyracephalonica eggs did not significantly weaken the performances of C. pallens in a Vicia faba–A. craccivora banker plant system compared to aphids. In conclusion, C. cephalonica eggs can be used for the mass production of C. pallens as the founder population in a banker plant system. Moreover, linking the life table data with the predation rate is an effective strategy for evaluating mass rearing programs in establishing banker plant systems.

Investigating the Efficacy of a Canine Rabies Vaccine Following Storage Outside of the Cold-Chain in a Passive Cooling Device

Background: Thermostable vaccines greatly improved the reach and impact of large-scale programmes to eliminate infectious diseases such as smallpox, polio, and rinderpest. A study from 2015 demonstrated that the potency of the Nobivac® Rabies vaccine was not impacted following experimental storage at 30°C for 3 months. Whether the vaccine would remain efficacious following storage under more natural, fluctuating temperature conditions remains unknown. We carried out a randomised controlled non-inferiority trial to compare serological responses in dogs following vaccination with doses stored under cold chain conditions with those stored within a locally made Passive Cooling Device (“Zeepot”) under fluctuating temperature conditions.Materials and Methods: Nobivac® Rabies vaccine was stored under either cold-chain conditions or within the Zeepot for 2 months. Daily ambient temperatures and temperatures within the Zeepot were recorded every 3 h. Following storage, 412 domestic dogs were randomly assigned to receive either cold-chain or Zeepot stored Nobivac® Rabies vaccine. Baseline and day 28-post vaccination blood samples were collected. Serological analysis using the Fluorescent Antibody Virus Neutralisation assay was carried out with a threshold of 0.5 IU/ml to determine seroconversion. In addition, the impact of dog Body Condition Score, sex, and age on seroconversion was examined.Results: The serological response of dogs vaccinated using Nobivac® Rabies vaccine stored within the Zeepot was not inferior to the response of dogs vaccinated using cold-chain stored vaccine (z = 1.1, df = 313, p-value = 0.25). Indeed, the 28-day post-vaccination group geometric mean titre was 1.8 and 2.0 IU/ml for cold-chain vs. non-cold-chain storage, respectively. Moreover, the percentage of dogs that seroconverted in each arm was almost identical (85%). There was a positive linear trend between Body Condition Score (O.R. 2.2, 95% CI: 1.1–5.1) and seroconversion, suggesting dogs of poor condition may not respond as expected to vaccination.Conclusions: Our study demonstrated the potency of Nobivac® Rabies vaccine is not impacted following storage under elevated fluctuating temperatures within a Zeepot. These results have potentially exciting applications for scaling up mass dog vaccination programmes in low-and-middle income countries, particularly for hard-to-reach populations with limited access to power and cold-chain vaccine storage.

Short term fluctuating temperature alleviates Daphnia stoichiometric constraints

In this study, we analysed how short term temperature fluctuation interacts with nutrient limitation in the vertical migrating Daphnia commutata. We hypothesize that short term (daily) temperature fluctuation will alleviate nutrient limitation. We carried out experiments analysing growth rates, phosphorus and RNA content of D. commutate grown under four different temperature regimes and two P-limited conditions. Our experiments showed that individuals grown under fluctuating temperature grew more than at the mean temperature. We estimated the expected sizes for the 15 °C treatment based on the Q10 and for the fluctuating temperature treatment. These expected sizes for both treatments resulted well below the observed ones. The P and RNA content of individuals grown at 10 °C were significantly higher than those at 20 °C, and when individuals grown at 10 °C were translocated to 20 °C they exerted an increased growth rate. Our results suggest that, under a regime of diel vertical migration, the temperature alternation would allow migrating organisms to alleviate the effect of severe nutrient limitation maintaining population growth. Under a scenario of global warming, where epilimnetic temperatures will increase, lake temperature will interact with nutrient limitation for consumers, but, organisms may be able to face these changes if they can still regularly move from a cold hypolimnion to a warmer epilimnion.