Budworm success

Studies to determine the effect of water stress on foliage quality and budworm success were conducted at 2 sites west of Jemez springs. New Mexico, Santa Fe National Forest. These sites were chosen such that differences In water availability to Douglas-flr trees would be maximized. Thirty trees were selected... 

Interestingly, several more variables were Included In the model dealing with male budworm success on the trees at the Barley Canyon site (Table IV). Terplnolene, cltronellyl acetate. 

Data from all three studies show that. In all cases, the terpene chemistry of young foliage, or qualitative defenses, was the most important factor In reducing budworm success. The protein complexlng capacity, or quantitative defenses, of this tissue was not Important In reducing budworm success In any of the studies. 

Nitrogen was found to be of little Importance except for the female model generated from the Barley Canyon Study. In this case, female success was Inversely correlated with foliar nitrogen levels. However, these levels, based on published data (18,19), do not appear high enough to be toxic to the budworm. This observation, in view of the Inverse correlation between total nitrogen and female budworm success, leads us to... 

All of our results Indicate that Increased productivity Is associated with reduced budworm success. In the Montana study this was evidenced by the relationship between budworm Infestation Intensity and bole radius. In the Barley Canyon study, the relationship between budworm growth and crown ratio, the 5 year growth Increment, and total nitrogen support this conclusion as well. Assuming that productivity declines with age, the positive correlation between budworm success and age also Implies that a decline In vigor Increases tree susceptibility to budworm. 

The study Involving water stress In the Jemez mountains suggests that changes In foliage quality due to stress positively Influences budworm success (17). Female adult budworm from larvae reared on stressed trees were 30% heavier, while the male adults were 20% heavier. In addition, a higher number of both sexes survived on stressed trees (Table VI). 

In all three studies, but particularly In the 2 dealing with resistance-susceptibility characteristics of foliage quality, specifically the higher quantities of terpenes were correlated with reduced budworm success. At any particular site all of the trees sampled contained the same basic complement of terpenes, albeit, some were present In low quantities. The effect, which we assume Is one of toxicity, of the terpenes In reducing budworm success, then, was due to an Increase In their quantitative amounts. In other words, the terpenes were acting In a quantitative or dosage dependent fashion. 

Phenological Synchronization. Induced delays in budbreak in balsam fir reduce feeding by the spruce budworm, and defoliation and desquaring in cotton depress overwintering success of several major cotton pests. Table IV presents a summary of the work on these two systems. 

Delisle, J. and Hardy, M. (1997). Male larval nutrition influences the reproductive success of both sexes of the spruce budworm, Christoneura fumiferana (Lepidoptera Tortricidae). Functional Ecology 11 451 163. 

The multiresistant strains now extant also show a certain cross-tolerance, but not resistance, to the third-generation insecticides such as the juvenile-hormone mimics and other so-called insect growth regulators, as was found in strains of the housefly, flour beetle and tobacco budworm. Resistance to the JH mimic methoprene and Monsanto-585 has been induced by laboratory selection of Culex taxsalis (28) and Culex pipiens (29), and to Monsanto-585 in Culex quinquefasstatus (30). Whatever insect or IGR is chosen, the result of exposure to selective doses in successive generations is usually the development of resistance, repeating our previous experience with chemosterilants, and the... 

---