DETECTABILITY OF HALYOMORPHA HALYS (HEMIPTERA: PENTATOMIDAE) BY PORTABLE HARMONIC RADAR IN AGRICULTURAL LANDSCAPES

Abstract

Harmonic radar technology enhances capability to track the movement of individual small insects under field conditions. To maximize the capacity of this technology, it is necessary that radar tags must be securely attached to insects and that the tags remain functional when subjected to mechanical stress. In this study, a series of experiments was carried out to test an improved harmonic radar tag designed to be more resistant to mechanical stresses and to establish that a portable harmonic radar system can effectively detect adult Halyomorpha halys Stal (Hemiptera: Pentatomidae) on various structures in different landscapes. The functional resistance of radar tags to similar to 1-m free falls on a hard surface was improved significantly by reinforcing the adhesive bond between the radar transponder and the radar wire by application of cyanoacrylate glue. This measure did not affect the detectability of radar tags, and it significantly increased the resistance of radar tags against random mechanical impacts inflicted on the insects and tags. The success rates of locating radar-tagged H. halys were compared among different landscapes, including a mowed grass-covered plot (250 m(2)), a mature peach tree plot (50 m(2)), and an unmanaged hedgerow (50 m(2)). The success rates were > 90% in all landscapes tested. There was no significant difference in the search time needed to locate tagged adults. In general, it took less than 2 min to detect and recover H. halys. The success rates of locating radar-tagged H. halys were also compared among different locations within mature fruit trees. There was no significant difference in the success rates between the inner third (87%) and the outer third of the host tree canopy (100%). However, a significantly longer period of time was required to locate H. halys in the inner canopy (372 s +/- 95 SE) compared with the outer canopy (148 s +/- 39 SE). When H. halys were concealed in the lower, middle and upper thirds of the outer tree canopy, the success rates of locating tagged adults were consistently 95% or greater at all canopy heights with no significant difference in search times needed to locate tagged adults. The results of this study provide context for researchers to reliably use this radar system in the field to study the dispersal biology of H. halys.