Pupal Development of <I>Aethina tumida</I> (Coleoptera: Nitidulidae) in Thermo-Hygrometric Soil Conditions Encountered in Temperate Climates

Abstract

The pupal development of Aethina tumida Murray (Coleoptera: Nitidulidae) was studied at various combinations of thermo-hygrometric soil conditions (temperatures of 16, 18, and 20 degrees C and soil water content levels of 0.37, 0.56, and 0.73 m3 water per cubic meter of dry soil) representative of southeastern Canada. Survivorship and development duration of A. tumida pupae, as well as sex ratio and life span of emerging adults, were assessed. Assays were conducted in growth chambers on an average of 50 third-instar larvae per thermo-hygrometric combination. Results show that survivorship of pupae decreased with lower temperature and higher soil water content. Pupal development time shortened as temperature increased (69-78 d at 16 degrees C, 47-54 d at 18 degrees C, and 36-39 d at 20 degrees C), but was longer in dryer soil. Optimal soil water content for pupal development was 0.56 m3 water per cubic meter of soil. We estimated that the minimum development temperature for pupae is between 10.2 and 13.2 degrees C, depending on soil water content. The sex ratio of emerging adults was influenced by soil water content. We measured one female to one male for dry and intermediately wet soils and three females to one male for wet soils. Higher soil water content reduced the life span of emerging adults by half. This study contributes to a better understanding of A. tumida population dynamics in eastern Canada.

Global warming promotes biological invasion of a honey bee pest

“…Green dashes lines indicate the optimal temperature for composite pupal performance (d) and visualise a decrease in development time from 43 days according to T opt to 18 days (c) while survival rate decreased only to 87% (a). Point colours indicate data sources: black, Bernier et al (); red, Ellis et al (); green, Meikle and Diaz (); dark blue, Meikle and Patt (); light blue, unpublished data from new experiment 1; magenta, unpublished data from new experiment 2 (see Table S1 and Method S1)…”

“…In contrast to other beetles, which can complete an entire life cycle within host colonies (Krishnan, Neumann, Ahmad, & Pimid, ), SHBs have to pupate in the soil to complete their life cycle (Ellis, Hepburn, Luckman, & Elzen, ; Lundie, ). SHB pupation success (survival rate) and the duration of pupation are governed by soil humidity and temperature (Akinwande & Neumann, ; Bernier, Fournier, & Giovenazzo, ; Ellis et al, ; Meikle & Diaz, ; Meikle & Patt, ). It is therefore apparent that abiotic factors can play a key role in explaining the performance and thus invasion success of this species.…”

Small hive beetle diagnosis and risk management options

“…Since the majority of SHB was found on the bottom boards (Neumann and Hoffmann, 2008) a trap located there presumably has a better chance of catching beetles compared to other locations in the hive (in case of nonscreened bottom boards). Comparing Beetle BarnTM, HoodTM and AJ's Beetle EaterTM traps did not reveal significant differences in efficacy of traps over different sampling dates (Bernier et al, 2014), probably because this study did not estimate the non-detection errors of any of the tested traps. The use of yeast-induced pollen dough as a bait in bottom board traps has been reported to capture significantly more beetles than unbaited traps , but again also this study failed to deliver a convincing sensitivity.…”

“…The control-type trap (Beetle Blaster) is placed between the top bars of two frames adding some mineral or vegetal oils and vinegar as bait. The latter type of bait is used because of its presumed attractive effect on Nitidulidae beetles, although there are no clear data underpinning it (Bernier et al, 2014). This trap can be used for both diagnostic and control purposes.…”

“…Propolisation of trap openings has to be checked and propolis removed if present. Trap efficacy could be compromised if propolis is not removed (Bernier et al, 2014).…”