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Behavioral and ecological factors influencing oviposition of Acrobasis vaccinii (Riley) (Lepidoptera: Pyralidae), the cranberry fruitworm, with implications for pest management
The cranberry fruitworm, Acrobasis vaccinii (Riley) (Pyralidae), is the most important insect pest of Massachusetts cranberries. The female lays her eggs individually in the calyxes of developing fruits. Upon hatching, the larva cats its way into the fruit and consumes it, whereupon it moves to another. Because the immatures are protected inside fruits, insecticides target the adult and egg stages. Growers wishing to practice integrated pest management (IPM) engage scouts to collect and check berries for eggs to determine whether spraying is warranted. However, their protocol was devised with limited knowledge of egg distribution or the relationship between eggs found and yield loss. Better understanding of the oviposition behavior of the female and of egg distributions is essential for effective monitoring. The quest to optimize scouting efficiency led me to explore the physical properties of cranberries and their immediate environment in order to identify factors influencing oviposition. Mechanosensory stimuli, including surface texture, conformation, size, geoörientation, and moisture content of the oviposition substrate, are important determinants in insect oviposition site selection, comprehensively reviewed in Chapter 1. In laboratory choice experiments described in Chapter 2, I manipulated the surface texture, conformation and geöorientation of cranberries and showed that physical contact with a natural calyx is important in eliciting oviposition. In field choice experiments, I showed that females are more likely to oviposit on the uppermost berries and on berries growing in abundant foliage. The balance of my research was designed to characterize the egg spatial distribution in commercial cranberry bogs and to develop an empirically-based IPM scouting protocol. Six bogs were intensively sampled and their egg distributions were modeled in Chapter 3 using Taylor's Power Law (Taylor, 1961), variance = a*meanb. However, exponential and logarithmic versions of the model produced different regressions. Comparisons of their performance demonstrated that exponential models usually produced more satisfactory descriptions of the variance to mean relationship. Analyses of the published data sets Taylor employed, presented in Chapter 4, obtained comparable results. In Chapter 5, I developed and tested a new scouting protocol based on the exponential model, which outperformed the original protocol in field trials.
Rogers, Andrea Kent Osgood, "Behavioral and ecological factors influencing oviposition of Acrobasis vaccinii (Riley) (Lepidoptera: Pyralidae), the cranberry fruitworm, with implications for pest management" (2000). Doctoral Dissertations Available from Proquest. AAI9960784.