Effects of Temperature and Density on House Cricket Survival and Growth and on the Prevalence of Acheta Domesticus Densovirus

Abstract

The house cricket, Acheta domesticus, is a commonly reared insect for food and feed purposes. In 1977, a report described a colony collapse, which was caused by the single-stranded DNA virus Acheta domesticus densovirus (AdDV). Currently, there are no confirmed A. domesticus colonies free of AdDV, and viral disease outbreaks are a continuous threat to A. domesticus mass rearing. Correlations between cricket rearing density or temperature and AdDV abundance have been hypothesized, but experimental evidence is lacking. Optimised rearing conditions, including temperature and density, are key to cost-effective cricket production. In this study, house crickets were subjected to different combinations of rearing density (10, 20, 40 crickets per box) and temperature (25, 30, 35 °C) to study the effect on cricket survival, biomass, and AdDV abundance. Rearing temperature affected had a minor effect on survival, which ranged between 80 and 83%. Total cricket biomass increased with higher temperatures and higher densities. Viral abundance in crickets at the end of the rearing period was variable; however, high rearing density seemed to result in higher AdDV abundance. At 35 °C, a temperature considered suboptimal for house cricket production, viral abundance tended to be lower than at 25 or 30 °C.

Keywords: Acheta domesticus; cricket viruses; entomopathogenic viruses; house cricket; insect production; insects as food and feed; mass rearing.

Figure 1

Median cricket survival was calculated over the three experimental runs. Temperatures tested are indicated along the X-axis. The Y-axis represents survival (%), horizontal lines depict the median, boxes indicate the lower and upper quartiles, vertical lines extend to minimum and maximum values, black dots represent outliers. Different letters indicate significant differences between the treatments.

Figure 2

Total harvested biomass (g) for each treatment group. Temperatures are indicated along the X-axis per density tested, indicated above the figure (D10, D20, or D40). The boxplots show the median total biomass (bold horizontal line), boxes depict lower and upper quartiles, vertical lines extend to minimum and maximum values, black dots represent outliers. Different letters indicate significant differences between the treatments.

Figure 3

Female individual weight (g) for each treatment group. Temperatures are indicated along the X-axis per density tested, indicated above the figure (D10, D20, or D40). The boxplots show the median individual weight (bold horizontal line), boxes depict lower and upper quartiles, and vertical lines extend to minimum and maximum values, black dots represent outliers. Different letters indicate significant differences.

Figure 4

Male individual weight (g) for each treatment group. Temperatures are indicated along the X-axis per density tested, indicated above the figure (D10, D20, or D40). The boxplots show the median individual weight (bold horizontal line), boxes depict lower and upper quartiles, and vertical lines extend to minimum and maximum values, black dots represent outliers. Different letters indicate significant differences.

Figure 5

Relative viral abundance in the three experimental runs. The Y-axis represents the fold of change in viral abundance, relative to the start levels, while the X-axis represents the different temperatures (three left−hand panels) and different densities (three right-hand panels). The boxplots show the lower and upper quartiles; vertical lines extend to minimum and maximum values, black dots represent outliers. Different letters indicate significant differences between the treatments.