No abstract

The recent introduction of the concept of refuge areas for the management of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera : Chrysomelidae), on resistant potato highlighted the existence of important gaps in our knowledge and understanding of this pest's movement within and between habitats. The objective of this review is to synthesize the information available for the benefit of crop managers and to identify subject areas in need of additional research. A traditional, somewhat encyclopedic, review of the old and recent literature on research methods, basics of flight and walking, as well as abiotic and biotic conditions for dispersal, revealed a considerable volume of information accumulated since the early 1900s. There is a consensus on the role of abiotic factors on flight and walking, but a better understanding of the biotic factors will be required before the variability of the dispersal response can be fully explained or predicted. Cybernetic models of orientation proposed in the literature were pulled together into a schematic representation of the orientation process in walking L. decemlineata. The model begins the integration of the different conditions and underlying suggested mechanisms responsible for the orientation of the walking beetle. There is remarkably little information on the orientation of potato beetles during flight. Finally, the seasonality of walking and flight dispersal is reviewed in relation to the host habitat and overwintering sites.

The wing loading of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), was found to decrease slightly with increasing size over a wide range of individual sizes and independent of sex. This makes it possible to use tags of the same weight for beetles of all sizes and suggests that if the addition of light electronic tags has any effect on the beetle's flight it will be similar across beetle size. The wing loading of individual potato beetles ranged from an average minimum 10.9 N m −2 to an average maximum of 15.6 N m −2 as their weights fluctuated over time following water and food uptake or dispersal. However, tests carried out in flight chambers indicate that beetles become incapable of upward flight as they go beyond an average wing loading of 11.8 N m −2 , that is 101 µN (10.3 mg) beyond their minimum weight. It is estimated from our results that electronic tags should weigh no more than 23-33% of the potato beetle's acceptable extra loading for the technique to have no or minimal impact on the number and quality of upward flights taken.

We evaluated the effectiveness of three cyanoacrylate glues (trade names: Krazy [Elmer's Products Inc., Westerville, OH], Loctite [Henkel Corporation, Rocky Hill, CT], and FSA [Barnes Distribution, Cleveland, OH]) to attach harmonic radar tags securely on adult Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) and quantified the effect of the radar tag attachment on insect survivorship and mobility. In the laboratory, the strength of the glue bond between the radar tag and H. halys pronotum was significantly increased when the pronotum was sanded to remove cuticular waxes. The adhesive bond of the radar tag to the sanded pronotum of H. halys had strength of 160-190-g force and there was no significant difference among the three types of glue tested. The three glues had no measurable effect on the survivorship of radar-tagged H. halys over 7 d, compared with untagged insects. Over a 7-d period in the laboratory, horizontal distance traveled, horizontal walking velocity, and vertical climbing distance were all unaffected by the presence of the tags regardless of glue. A field experiment was conducted to compare the free flight behavior of untagged and radar-tagged H. halys. Adults were released on a vertical dowel and their flights were tracked visually up to ≍200 m from the release point. There was no significant difference in take-off time or in flight distance, time, or speed between untagged and radar-tagged individuals. In addition, prevailing flight direction was not significantly different between untagged and radar-tagged individuals. The absence of measurable impact of the radar tag attachment on H. halys survivorship or mobility validates the use of harmonic radar tags to study the dispersal ecology of this insect in field conditions.

The ability of three cyanoacrylate glues to ensure a durable bond between the Colorado potato beetle, Leptinotarsa decemlineata (Say), the plum curculio, Conotrachelus nenuphar (Herbst), or the corn rootworms (Western Corn Rootworm, Diabrotica virgifera virgifera LeConte and Northern Corn Rootworm, Diabrotica longicornis Smith and Lawrence) and the harmonic radar tag without impact on behavior and survival was assessed as part of a study on the use of harmonic radar technology to track these insect pests. Droplets of 0.1 mg of Krazy Glue, Loctite, and Bowman FSA applied to the pronotum had no effect on the survival of the Colorado potato beetle or plum curculio after 5 and 7 d, but caused > 40% mortality after only 4 h with both the western and northern corn rootworms. The three glues created an effective bond lasting 4-5 d between the harmonic radar tag and the Colorado potato beetle in > 85% of cases and the plum curculio in almost 50% of cases. There was no detectable impact of the glue treatment on feeding or walking behavior of the Colorado potato beetle. Analysis of the same behaviors with the plum curculio showed no impact on the ability to walk on a vertical surface, the speed of travel, or the duration of travel. There was no significant impact on feeding by female plum curculio but indication that males treated with Krazy Glue fed less. Overall, results quantified the effectiveness of the cyanoacrylate glues at providing a durable bond with no significant impact on mobility or behavior of the Colorado potato beetle or plum curculios. However, the toxicity of the glues against the corn rootworms suggests that similar toxicity or sublethal effects may exist with other insects.