Dk. Giles et Lr. Wunderlich, ELECTRONICALLY CONTROLLED DELIVERY SYSTEM FOR BENEFICIAL INSECT EGGS IN LIQUID SUSPENSIONS, Transactions of the ASAE, 41(3), 1998, pp. 839-847
A mechanical system was developed to meter and discharge liquid suspen
sions of insect eggs for release of biological pest control agents. Th
e system consisted of a reservoir that was pressurized by compressed a
ir which distended the bottom surface of the reservoir agitated the su
spension and forced it through a liquid supply tube which terminated i
n a tapered orifice. A pulse-width modulated valve provided intermitte
nt flow which produced large droplets (ca. 2 mm diameter) of suspensio
n. The duration of and intervals between liquid pulses, which determin
ed application rate of and spacing between discharged eggs, respective
ly, was controlled by a microprocessor. Liquid droplets could be prope
lled outward to 3 m and at flowrates ranging from 25 to 250 ml/min per
orifice. In operation, discharge distance of the eggs was controlled
by the reservoir pressure, ranging from 10 to 50 kPa, and the flowrate
was controlled by the duty cycle, or relative open time of the meteri
ng valve (10 to 100%). The system provided adequate agitation to disch
arge uniform suspensions of eggs in liquid carriers for 50 min and did
not reduce viability of green lacewing eggs as measured by bioassays
of larvae emergence from discharged eggs.