Biology, Ecology, and Management of Key Pests of Satsuma Citrus in Alabama
Type of Degreedissertation
Entomology and Plant Pathology
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Satsuma mandarin (Citrus unshiu Marcovitch) production is an emerging industry in Alabama. Recent surveys identified Leptoglossus zonatus (leaffooted bug), Phyllocnistis citrella (citrus leafminer), and Panonychus citri (citrus red mite), as important pests of satsuma in Alabama. My dissertation comprised of three sections with the focus on the ecology and management of the above three key pests, and included laboratory and field studies. The first section (chapters II and III) focused on L. zonatus. Host preference and development of L. zonatus was studied in chapter II. The results showed that tomato was the most preferred fruit, but satsuma is also a suitable host. Damage to satsuma by L. zonatus was evaluated in chapter III. Feeding by L. zonatus on satsuma produced external damage, and resulted in significant fruit weight loss, fruit abortion, and reduced soluble solids content (SSC). Section 2 (chapters IV and V) focused on P. citrella. The seasonal phenology and natural enemy fauna of P. citrella in Alabama was investigated in chapter IV. The results showed multiple overlapping generations of P. citrella, and effective pheromone-baited traps were identified. At least 21 species of beneficial arthropods were recorded. In chapter V, I investigated the relative contributions of key beneficial arthropods to natural mortality of P. citrella in Alabama using exclusion techniques. Predation by spiders was the most important natural mortality factor, whereas parasitism was minimal. Section 3 (chapters VI and VII) focused on P. citri. Chapter VI presented a laboratory evaluation of three commercially available predacious mite species in the family Phytoseiidae (Phytoseiulus persimilis, Galendromus occidentalis, and Neoseiulus californicus), as potential biological control agents of P. citri. All three species were effective in regulating P. citri density, but P. persimilis showed the highest predation potential followed by G. occidentalis. The results of field evaluations of small-scale releases of P. persimilis or G. occidentalis against P. citri (chapter VII) showed that two timed releases of either species at an appropriate release rate (100 or more per tree) provided effective season-long suppression of P. citri. These results support the development of an IPM program for satsuma production in the Gulf Coast region.