The assessment of arthropod abundance in crops is critical for investigating population dynamics of species and species interactions. However, acquiring reliable population estimates that reflects the true abundances of arthropods in the field is challenging. Here we describe the modification and application of a leaf blower-vac for suction sampling of arthropods in rice.
In the first section of this video, we will explain the stepwise modification of a leaf blower-vac for suction sampling. In the second part, we will explain how to use the blower-vac sampler in the field. In the third part, we will show the sampling results.
First, we need to collect all parts that are necessary for the modification. For this video, we used an Oleo-Mac BV300 Leaf Blower-Vac that is commercially available. PVC pipe one has a diameter of 110mm and will be connected to the blower-vac.
PVC pipe two is a standard 110mm diameter pipe and will be used to connect PVC pipe one to PVC pipe three, which will reduce the pipe diameter from 110mm to 50mm. PVC pipe four is a standard 50mm diameter pipe and will be used to connect PVC pipes three and five. PVC pipe five will further reduce the pipe diameter to 32mm.
PVC pipe six will enlarge the diameter of the mouth part from 32mm to 63mm. PVC pipe seven is a standard 63mm diameter pipe which will form the suction mouth of the machine. The end of this pipe will be connected to the hose.
The hose should fit the diameter of pipe five and six, and should be about one meter long. It should be reinforced with metal because it has to withstand the considerable suction force of the blower-vac. Metal hose clamp one will be used to fasten the hose to pipe five.
A second metal hose clamp will be used to fasten the hose to the mouth part. A metal gauze is used to prevent material to be sucked into the machine. The connection between the PVC pipes and the hose will be sealed by thread seal tape.
UPVC Glue will used to connect the PVC pipes. Finally, three screws are needed to connect the pipes to the machine. Keep in mind, that a different size of PVC pipe one may be needed, depending on the type of machine that you are using.
The other pipes may then need to be changed accordingly. Important here is that the outer diameter of the open end of pipe one seamlessly fits the inner diameter of the suction mouth of the machine for optimal performance. Furthermore, the diameter of pipe seven should not be too big or too small.
A too big pipe will reduce the suction power. While a too small pipe will reduce the sampling efficiency because of the smaller sampling area. Now that we have collected all parts, we can start to assemble the blower-vac sampler.
Take the pipes, UPVC Glue and thread seal tape. Clean all surfaces that need to be glued together. Connect pipe one to pipe two by adding a thin layer of glue to the inner part of pipe one and a thick layer of glue to the outer part of pipe two.
speaker pauses six seconds*Then insert pipe two into pipe one immediately after adding the glue and remove any excess glue. Next, connect pipe two to three by adding the glue in a similar way and insert pipe two into pipe three. speaker pauses 10 seconds*Repeat these steps to connect pipe three to four, pipe four to five and pipe six to seven and let the glue dry.
The result should look like this. Now you can connect pipe one to five to the leaf blower-vac. Insert the open end of pipe one into the inlet of the leaf blower-vac.
Make sure that the pipe does not touch the fan. Drill three evenly spaced holes through the machine and pipe. Approximately five millimeters from the edge of the connection and fix the pipe to the machine using three screws.
Do not use glue to connect the PVC pipe to the machine because you should be able to open it to clean the fan. Now we can connect the hose. First, put thread seal tape to the open ends of pipe five and six to make a seamless connection between the pipes and the hose.
Then connect the hose to pipe end five using the metal hose clamp. Cover pipe end six with the piece of metal gauze and connect the hose to pipe end six while keeping the metal gauze in place. The metal gauze in the suction mouth prevents debris to enter the machine.
The blower-vac sampler is now ready for use. However, before you use it, first check whether all connections are tight. The second step is to prepare the sampling enclosure.
Take a 50 liter bucket with a 40cm bottom diameter and remove it's bottom. The bottom area will be approximately one eighths of a square meter. Attach nylon mesh sleeve with a length of approximately one meter, to the top of the bucket using a rubberband.
After assemblage, the blower-vac sampler can be used for arthropod sampling in the field. Once arrived at the study site, you can start the machine. With the machine running, you can insert a sampling net into the mouth part and secure it with a rubberband.
speaker pauses five seconds*Now that the machine is ready to use, another person can abruptly place the enclosure over the plants of the sampling location. Make sure that the sleeve is closed to prevent arthropods from escaping from the top of the enclosure. Push the bottom of the bucket firmly into the soil so that no arthropods can escape from the bottom of the enclosure.
Remove all arthropods from inside the enclosure in a top-down spiraling way for a standardized sampling duration. The sampling time should be adjusted to the plant size, structure and planting density to maintain a similar level of efficiency. Sampling efficiency should be checked by careful official inspection of the enclosed area after sampling.
speaker pauses four seconds*After finishing the sample, remove the rubberband from the sampling net, rapidly close the net and take it out of the mouth part of the blower-vac while keeping the machine running to prevent arthropods from escaping. The sampling net can be closed with a knot or by using a rubberband. speaker pauses 10 seconds*Once the sample has been safely secured, the next sample can be taken.
We conducted eight samples in a ripening stage rice field, with a three minute sampling duration. No arthropods were found within the enclosure upon official inspection after each sample was taken. A total of 298 arthropods belonging to eight orders were collected.
The mean number of individuals per sample was 37 four. The top three most dominant orders are Hemiptera, Araneae and Diptera. In each sample, our three minute sampling was divided into six sub-samples of 30 seconds each.
The first 30 seconds yielded more than half of the total number of individuals. After two minutes sampling, the relative yield as a percentage of the number collected after three minutes, was 92.4%After two and a half minutes the relative yield was 97.3%In conclusion, the modification of the blower-vac described here, is easy to carry out. Easy to use in the field and our results show that the blower-vac sampler is efficient.
Which enables us to acquire reliable population estimates that reflect the true abundances of arthropods in rice fields. Thanks for watching and good luck building your own blower-vac sampler.
