Vertical distribution profile of Colorado potato beetle [Coleoptera: Chrysomelidae] in flight above host, resistant host and non-host fields

Abstract

We evaluated the vertical stratification of Colorado potato beetle (Leptinotarsa decemlineata) (CPB) populations in flight above fields of conventional potato, an insect resistant potato field expressing genes for Bacillus thuringiensis tenebrionis (Btt) toxins and a non-host clover field. Flight interception traps at 0 - 1.2, 1.2 - 2.4 and 2.4 - 3.6 m above ground were used to determine the vertical profiles of the aerial population over each crop for a growing season. The distribution of overwintered and summer CPB catches above conventional potatoes was similar with a significant effect of trap height on catch. The same vertical distribution profile was observed for overwintered CPB and a similar trend for summer CPB above the insect resistant field. Few overwintered beetles were captured over the clover field but enough summer CPBs were caught to detect a trend similar to that on resistant potatoes. Additional data show that more than 70% of CPBs fly less than 4 m in distance at a height of less than 2 m. These data suggest that the vertical flight profiles observed result from local dispersal of resident populations, or low level flights of summer beetles, but not from high level flights of dispersing overwintered adults.

Harmonic radar: efficacy at detecting and recovering insects on agricultural host plants

“…Spencer et al 4 determined that 85–90% of western corn rootworm movements are local and of short distance (4.6–9.1 m day −1 ). The relationship between the height of flight at take‐off and the distance flown by adult Colorado potato beetle was studied5 by visually observing individuals leaving a release point at the centre of a 10 m radius potato field arena. Likewise, behavioural studies of adult plum curculios labelled with the radioisotope Zn 65 allowed a better understanding of its field behaviour,6 and, ultimately, the results were used to design optimal management strategies 7…”

Contribution of habitat type to residency and dispersal choices by overwintered and summer adult Colorado potato beetles

“…The relative quality or plant phenology of habitats (Mbungu & Boiteau, ) could generate different CPB dispersal rates. MacQuarrie & Boiteau () observed more flights from summer CPB exposed to poor host than to conventional potato. Each seasonal beetle type is likely to have evolved different dispersal strategies (Jermy et al., ; Weber & Ferro, ).…”

“…Each seasonal beetle type is likely to have evolved different dispersal strategies (Jermy et al., ; Weber & Ferro, ). MacQuarrie & Boiteau () recorded summer CPB flights, but essentially no overwintered beetle flights, in a pasture. They suggested that overwintered CPB limit their dispersal to within host fields or to higher altitude across non‐host fields.…”

“…Alternatively, dispersal level may be similar between host and non-host habitats but the number of CPB dispersing by flight over that by walking (dispersal mode) could differ. Emigration from potato by flight may have been underestimated because flight is difficult to monitor (MacQuarrie & Boiteau, 2003;Boiteau et al, 2014). Also, mixed vegetation crop borders act as temporary barriers to walking CPB but not to flight (Boiteau et al, 2014).…”

“…Our objective was to determine whether adult CPB emigration rates and the ratio of dispersal by flight over walking differ between host and non-host habitats, and whether seasonality and hunger level contribute to the possible differences. The ability of CPB to disappear from sight in the crop or surrounding vegetation makes it difficult to visually track the dispersal of the CPB over any significant period of time (MacQuarrie & Boiteau, 2003). The use of box-plots ( Figure 1) made it possible to quantify the walking and flight dispersal of released marked overwintered and summer CPB over a period of 4 days simultaneously in six habitats.…”