SUSTAINING THE WORLD THROUGH SCIENCE AND TECHNOLOGY

Collecting Methods


Sweeping, vacuum sampling, malaise and light traps are all effective methods of collecting delphacids.  All these methods generally carry the disadvantage that you learn little about the host, although one might sweep or vacuum individual plant species.  Alternatively, beating individual plants into a white pan, and picking up planthoppers with an aspirator or collecting tube yields valuable information about hosts, but is quite labor intensive.

Sweeping has the advantage of being simple and requiring the least amount of specialized equipment.  Many short-winged forms will be captured in sweep samples, although species that dwell low on plants or in the thatch may be missed, and these are often the species of greatest interest.   A “D” frame net has been recommended by some.  Sweeping is generally more effective than malaise traps or light traps in surveying the diversity and numbers of delphacids; however, vacuum sampling may be more effective at producing the rarer taxa.  It is generally easiest to process net contents in the field by holding the net open and aspirating planthoppers as they attempt to escape.

Malaise traps are a good passive method of collecting many types of insects.  Dispersal forms can sometimes show up in numbers in malaise samples, although brachypterous forms are seldom collected.  Malaise traps are good for collecting quantitative and seasonal data on planthopper abundance.

Many delphacids come to lights, sometimes in large numbers.  Brachypters may be attracted to lights from the immediately surrounding vegetation.  On average, sweeping is more effective in surveying delphacid diversity than light collecting, but some taxa – such as Pareuidella and the New World members of the genera Euides and Nilaparavata  - are more readily taken at lights than sweeping. 

Vacuum sampling may be one of the most effective ways of collecting delphacids, particularly those taxa that dwell low on the plant or in thatch (epigeic species) that would otherwise be missed by sweeping, and would not ordinarily come to malaise or light traps.  An inexpensive vacuum sampler can be assembled by affixing a mesh net to the intake tube (by tape or rubber bands) of a gas-powered leaf blower that has been arranged for vacuuming.  This type of arrangement is excellent for sampling bunch-grasses or sedges that grow in clumps that otherwise could not be sampled by sweeping.  Samples taken this way can be processed in the field similar to a sweep sample, or specimens can be extracted by dumping the sample into a darkened container.

Additional methods would include spreading host plant vegetation flat against the ground and aspirating individuals that come up out of the vegetation.  Beamer (1946) suggested flooding vegetation growing in water to force hidden insects out.  Beamer also suggested cutting bunched vegetation close to the ground and shaking the hidden insects out of the cut portion, and by sweeping or beating the stubble.