The Effect of Soil Temperatuers on the Distribution of Neodiprion Sawfly Cocoons

Abstract

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Preliminary Life Tables for Pine Sawflies in the Neodiprion Fulviceps Complex (Hymenoptera: Diprionidae)

“…The elevation in Area I was 4,000 feet, in Area II, 4,500 feet, and in Area III was 5,000 feet. Plant development proceeded up slope as would be expected but the N. fulviceps population in Area I developed much later than the populations in the upper two areas (Dahlsten 1966).…”

“…Shasta was calculated by subtracting the total number of cocoons collected in the 6-ft radius circle beneath the tree crown (or 4-ft circles multiplied by the correction factor 2.6) from estimated number of larvae available to spin cocoons. It has been shown that a 4-ft circle contains approximately 77.5% and a 6-ft circle 89.5% of the total number of cocoons present in a 9-ft radius circle (Stark and Dahlsten 1961). As this study was performed on a 16-ft tree in the open, it is believed that the percentage collected from the smaller trees at Mt.…”

“…Shasta was similar to that found for other populations of sawflies (Dunn 1934, Schedl 1939. Schedl (1939) (Dahlsten 1966), it was calculated that mortality of 98.7% in Area I, 98.3% in Area II and 97.5% in Area III would be necessary to maintain populations at their present level. However, if the sex ratio is taken into consideration, the percentages drop as follows : Area I-95.1% ; Area 11-95.0% ; and Area III-91.6%.…”

“…As this study was performed on a 16-ft tree in the open, it is believed that the percentage collected from the smaller trees at Mt. Shasta is correspondingly higher (Stark and Dahlsten 1966).…”

“…These studies indicated a number of biological differences between the sawfly population at Willits and those at Mt. Shasta (Dahlsten 1966). No morphological characters could be found but the biological differences indicated that there were three distinct populations or species being dealt with (one at Willits and two at Mt.…”