. Commercial mass culture of the California red scale parasite : Aphytis lignanensis. Citrus; Scale insects. and economical operation upon this in- formation more than upon any other single body of data. Graph 5 shows the results of tests utilizing a wide range of combinations of parasite and host densi- ties. The objective in testing these combina- tions was to determine which would give a progeny production most closely ap- proximating the desired 1:1 ratio of female progeny to female parents and still give high host utilization. Study of graph 5 shows that although maximum total progeny pro
. Commercial mass culture of the California red scale parasite : Aphytis lignanensis. Citrus; Scale insects. and economical operation upon this in- formation more than upon any other single body of data. Graph 5 shows the results of tests utilizing a wide range of combinations of parasite and host densi- ties. The objective in testing these combina- tions was to determine which would give a progeny production most closely ap- proximating the desired 1:1 ratio of female progeny to female parents and still give high host utilization. Study of graph 5 shows that although maximum total progeny production oc- curs at the combinations involving high host-scale densities, the closest approxi- mation to the desired 1:1 parent-progeny ratio occurs with five combinations—15 parasites to 25 scales, 20 parasites to 35 scales, 25 parasites to 45 scales, 30 para- sites to 55 scales, and 35 parasites to 65 scales. This gives a choice of combina- tions covering all possibilities likely to be used in mass culture. The first of these (15 parasites to 25 scales) results in a female parasite progeny population of per square centimeter. This represents a high degree of host-scale utilization (72 per cent parasitization) but a rather low total progeny production per square centi- meter because of the low scale density. The most important consideration is progeny production per square centi- meter. The second combination (20 para- sites to 35 scales) yields female parasite progeny per square centimeter, which represents an increase in total parasite production but a decrease in per cent parasitization to 64. The remain- ing combinations show successive incre- ments in female progeny production to , , and per square centi- meter. Per cent parasitization declines PARASITE PROGENY PER SQUARE CM. OF SQUASH SURFACE. 20 NUMBER OF PARA- SITES PER SQUARE D CM. OF SQUASH SUR- Please note that these images are extracted from scanned page images that may have be
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