Density, size, and mortality of egg masses in New Jersey populations of the gypsy moth (Lepidoptera: Lymantriidae)
1990
Williams, D.W. | Fuester, R.W. | Metterhouse, W.W. | Balaam, R.J. | Bullock, R.H. | Chianese, R.J. | Reardon, R.C.
Observations on egg mass density, number of eggs per mass, parasitism, and viability of eggs of the gypsy moth, Lymantria dispar (L.), were caused out over 19 yr at 17 permanent study plots in New Jersey. Egg mass size (eggs per mass) in the current generation was inversely related to density in the previous generation. Eggs were parasitized entirely by Ooencyrtus kuvanae (Howard); parasitism averaged 25.9% overall. Percentage parasitism of eggs in a mass was negatively correlated with size. Percentage parasitism in the current generation was directly proportional to egg mass density in both the previous and current generations, falling below 10% in the most sparse populations and climbing above 35% in the most dense. The viability of unparasitized eggs in 1981-1989. When populations underwent outbreaks in most plots, was strongly negatively correlated with the percentage defoliation of oaks and less so (albeit significantly) with average monthly temperatures in October and February.
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