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

Abstract

The walking and flight dispersal of marked overwintered and summer Colorado potato beetles (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), released in field box‐plots was monitored simultaneously in six habitats over a period of 4 days. The emigration out of plots by walking beetles was calculated from the catch in linear pitfall traps completely surrounding each box‐plot and emigration flight was estimated from the number of beetles missing from the plot or captured by the trap. Overwintered beetles dispersed sooner after release than summer beetles. Overall, the mean number of beetles retained by the habitat was significantly higher in the host habitat (potato) than in any non‐host habitat tested (soybean, pasture, bare ground, water, woodland). Unexpectedly, there was no or little difference in overall beetle retention between non‐host habitats except for higher retention in the water habitat. No difference in the ratio of flight over walking could be detected by the study between overwintered and summer CPB except in the water and woodland habitats. Twenty‐four hours after release, the highest ratios were obtained in the water and woodland habitats and the lowest in the bare‐ground habitat, but ratios were similar for all habitats, except water, after 96 h. As a population, under these experimental conditions, 96 h after release, it seems that CPB displayed a slight preference for flight over walking, with walking as a default mode. A fed and starved pre‐release treatment had no effect on dispersal rates or mode of dispersal. Essentially, our results showed that over a 96‐h period, northeastern North American CPB emigrated at similar rates from the various non‐host habitats encountered, except for water, using walking as much as flight. The host habitat retained CPB significantly longer than non‐host habitats but with a mode of dispersal ratio similar to that in non‐host habitats. The impact on dispersal of the various habitats encountered by CPB in the agro‐ecosystem was less important than expected suggesting that the interaction of environmental parameters is likely to have the most significant impact in determining dispersal rates and dispersal modes.

Measuring host plant selection and retention of Halyomorpha halys by a trap crop

“…Each model contained the release habitat (pepper or trap crop), sampling period (flowering, fruiting, or post‐harvest), and sex (male or female) as explanatory variables, and release date as a random blocking variable to control for abiotic variables. The second‐order interaction between sampling period and release habitat was also included on the basis that different habitats have varying retention capacities (e.g., Boiteau & Mackinley, ), and that phenology of crops often impacts the abundance of H. halys (Martinson et al., ). In addition, the model examining distance moved also contained the time since release (1, 3, 6, or 24 h after release) as an additional explanatory variable.…”

Effects of contemporary agricultural land cover on Colorado potato beetle genetic differentiation in the Columbia Basin and Central Sands

“…In the spring, beetles emerge from overwintering sites in the soil, and typically walk, rather than fly, in search of the nearest potato crop, orienting by olfactory cues (Boiteau, Alyokhin, & Ferro, 2003). Greater distances between potato fields together with unfavorable composition of the intervening landscape can impede navigation of CPB and make it difficult for CPB to reach a potato field; for example, water bodies, cereal crops, and grassland present barriers to CPB movement (Boiteau & MacKinley, 2015Huseth et al, 2012;Lashomb & Ng, 1984). On the other hand, because potato attracts and retains CPB, areas with sparse potato land cover could unexpectedly enhance connectivity, because successful migrants must travel farther than beetles from areas with dense potato land cover.…”

Response of adult Colorado potato beetles (Coleoptera: Chrysomelidae) to water in the landscape

“…The temperature and light conditions during the laboratory trials were not conducive to beetle flight. Outdoors, Boiteau and MacKinley (2015) found that of more than 80% of Colorado potato beetles released on a platform in the middle of a water surface had abandoned it after 96 hours, with 64% flying off (rather than swimming off), demonstrating that flight can play an important role in improving their survival once drifting beetles have encountered driftwood or other floating debris.…”

“…This near water density combined to the hydrophobic cuticle makes the beetle very buoyant. Supported by the water surface tension, these floating beetles can easily be dispersed by wind as observed by Boiteau and MacKinley (2015) in water-filled outdoor box plots. Adding soap to the water of some of our test bottles removed the water surface tension and beetles immediately sank just below the water surface.…”

“…The ability of the Colorado potato beetle to swim, tolerate submergence and float on water all help increase the probability of surviving the threat of drowning and transform a water barrier into a non-barrier. Changing temperature above water that may at times force beetles to land on their surface (Hurst 1975) may also make it possible for them to fly off floating debris (Boiteau and MacKinley 2015). It is not clear how far above water the Colorado potato beetle can fly but the absence of successful Colorado potato beetle mass flight over the English Channel provides us with a maximum upper limit of 30 km (Hurst 1975).…”