Canopy distribution and microclimate preferences of sterile and wild Queensland fruit flies

Abstract

Insects tend to live within well-defined habitats, and at smaller scales can have distinct microhabitat preferences. These preferences are important, but often overlooked, in applications of the sterile insect technique. Different microhabitat preferences of sterile and wild insects may reflect differences in environmental tolerance and may lead to spatial separation in the field, both of which may reduce the control program efficiency. In this study, we compared the diurnal microhabitat distributions of mass-reared (fertile and sterile) and wild Queensland fruit flies, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). Flies were individually tagged and released into field cages containing citrus trees. We recorded their locations in the canopies (height from ground, distance from canopy center), behavior (resting, grooming, walking, feeding), and the abiotic conditions on occupied leaves (temperature, humidity, light intensity) throughout the day. Flies from all groups moved lower in the canopy when temperature and light intensity were high, and humidity was low; lower canopy regions provided shelter from these conditions. Fertile and sterile mass-reared flies of both sexes were generally lower in the canopies than wild flies. Flies generally fed from the top sides of leaves that were lower in the canopy, suggesting food sources in these locations. Our observations suggest that mass-reared and wild B. tryoni occupy different locations in tree canopies, which could indicate different tolerances to environmental extremes and may result in spatial separation of sterile and wild flies when assessed at a landscape scale.

Hierarchizing multi-scale environmental effects on agricultural pest population dynamics: a case study on the annual onset ofBactrocera dorsalispopulation growth in Senegalese orchards

“…As temperatures above 35°C challenge all components of BD life history, spatial and inter-annual weather variability in the Niayes region is likely to interact with local factors providing higher levels of humidity and shading (e.g. water bodies and groundwater, vegetation and soil moisture, canopy structure) to create favourable microhabitats allowing BD to mitigate hydric and thermal stress during the dry season (Inskeep et al, 2021; Mutamiswa et al, 2021). In addition to physical factors, the boosting approach also identified three landscape features that influenced the timing of the annual re-infestation of mango orchards.…”

Male Mediterranean fruit flies prefer warmer temperatures that improve sexual performance

“…For fruit flies, even within orchards planted with single cultivars, there are opportunities to locate cooler, more sheltered microhabitats due to the complex three-dimensional structure and evaporative cooling afforded by tree canopies (Pincebourde et al, 2012). Thermoregulatory behaviour has been noted in orchard tree canopies by C. capitata, and also in the Queensland fruit fly, Bactrocera tryoni, where flies moved lower in the canopy to avoid the heat of the day (Inskeep et al, 2021;Kaspi and Yuval, 1999).…”

Raspberry ketone feeding makes Queensland fruit fly, Bactrocera tryoni (Froggatt), more vulnerable to desiccation but not starvation

“…However, nature is unpredictable in terms of food availability, and natural sources of protein are thought to be often scarce and poor quality 32,33 . Factors like the fruiting status of trees, season, canopy distribution and microclimate affect protein availability 34,35 …”

“…32,33 Factors like the fruiting status of trees, season, canopy distribution and microclimate affect protein availability. 34,35 There are diverse strategies by which animals can respond adaptively to adverse environments. Insects have evolved behavioral, morphological and physiological adaptations such as reduced cuticular permeability, reduced excretory water loss, increasing water storage, enhancing tolerance to water loss and differences in the quantity and composition of cuticular lipids to balance water in warmer and drier environments.…”