The potential of portable harmonic radar technology for the tracking of beneficial insects
Titel:
The potential of portable harmonic radar technology for the tracking of beneficial insects
Auteur:
Boiteau, Gilles Colpitts, Bruce
Verschenen in:
International journal of pest management
Paginering:
Jaargang 50 (2004) nr. 3 pagina's 233-242
Jaar:
2004-07
Inhoud:
Visual observation enables a good understanding of beneficial insect behaviour within a locality, but once the rapidly dispersing beneficial insects walk or fly, they are soon lost from view. The harmonic radar tracking system developed to follow Colorado potato beetles, Leptinotarsa decemlineata (Say) in flight is proposed as a useful technique to increase the study range of beneficial insects from that of the plant to that of the landscape. These insects belong to a wide array of orders and families and many are small in size. Nevertheless, we estimated that some 15% of beneficial insects are at least similar in length to the chrysomelid beetle for which the feasibility of using a portable harmonic radar has been successfully demonstrated. As for the Colorado beetle, the pulsed radar transmitter, the tag, the antenna gain and the receiver of the portable radar system must be carefully designed to provide both a sufficient tracking range and a sufficient beam width. The construction of the tag is strongly limited by the load-carrying ability of the beneficial insect to be tracked. For the tracking of normal insect dispersal tags must, by definition, be lighter than the maximum carrying ability for extra loads and within the wing loading range of each species. It has been shown that in herbivorous insects and mosquitoes the ability to fly may be traded against the opportunity to acquire a large meal. This trade-off, which limits the ability of the insects to carry extra loads, should be less likely to occur with beneficial species that have to remain highly mobile to locate and capture prey for example. This was supported by our findings for Hippodamia convergens and Harmonia axyridis (Coccinellidae), both of which retain their ability to fly over the full range of their wing loading values. Tests conducted in the laboratory showed that these two beneficial insects can display normal flight behaviour with tags representing a similar percentage of their body mass as those successfully developed for the Colorado beetle and only slightly higher than for the other ones reported in the literature. The application of the portable harmonic radar technology to the study of flight by beneficial insects is therefore feasible and worth developing further. The main challenge is in the development of electronic tags with a sufficiently small absolute mass. Many options available immediately and others with potential are discussed.
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