Factors that interfere with attraction of apple maggot flies to traps were studied to provide a baseline for optimal trap deployment in apple orchards. I found a four-fold increase in captures of mature flies when butyl hexanoate was added to unbaited red spheres. The addition of ammonium carbonate or food presence did not affect mature fly response to traps. Wild flies immigrating into commercial orchards were primarily mature and not hungry for protein. Flies released outside blocks of apple trees of different sizes were intercepted in larger proportions by traps on small and medium sized trees than on similar traps on large trees. Overall trap performance was not strongly affected by orchard structure. Released flies were recovered in larger proportions by traps on McIntosh trees than by traps on Red Delicious trees bearing larger darker fruit. Visual competition became stronger as Red Delicious apples grew in size and turned in color. Decreased trap apparency on Red Delicious trees was compensated for by increased residence time of wild flies. Wild flies were captured in larger numbers by red spheres and Ladd traps than by yellow panels. Red spheres lost capturing power towards harvest when competing visually with red fruit. Ladd traps were not equally affected, but were more sensitive to trap positioning than red spheres. Red sphere effectiveness was restored after harvest. Optimal trap positioning may need to be revised. Wild fly accumulation on traps on tees of different apple cultivars during the growing season revealed that fly distribution in orchards is not exclusively governed by fruit ripening but rather by apple maggot preferences for some cultivars. Although ripening stage affected the onset of increases in fly accumulation on traps, some cultivars never accumulated many flies during the growing season. Apple maggot preferred to oviposit in sweet moderately firm fruit, but avoided ovipositing in excessively hard or soft fruit of different apple cultivars. Females also avoided fruit of late cultivars, even when sugar content and firmness were high and moderately high. Ovipositional cultivar preferences did not necessarily translate into greater fly accumulation on traps in our orchard study.

Dispersal and reproduction of the Colorado potato beetle, Leptinotarsa decemlineata (Say), with and without Bacillus thuringiensis subsp. tenebrionis Cry3 A δ-endotoxin in the environment were investigated through a series of field and laboratory studies. Possible implications for resistance management are discussed. Mating behavior of post-diapause beetles was observed. The influence of spring mating on beetle flight was investigated using a flight mill system. The beetles mated at the overwintering site, as well as in the potato field, and in the fields rotated out of potatoes. Mating status did not affect beetle flight, while absence of food encouraged flying over long distances. Dispersal of the summer-generation beetles was studied using a mark-recapture method. Effect of female age at the time of mating on the production of viable offspring was tested in the laboratory. Flight behavior of mated and unmated beetles was quantified on a flight mill. About 25% of the beetles remained close to the site of their pupation when they reached sexual maturity. Beetles produced viable offspring only if they accumulated at least 34 DD before mating. The largest number of flights was recorded for the unmated females. Use of phosphoglucomutase allozymes separated by cellulose acetate gel electrophoresis as genetic markers showed that sperm precedence in the Colorado potato beetle was incomplete, with about 72% of the larvae fathered by males at the second mating. A flight mill system was used to determine the effect of feeding on transgenic potato foliage, potato foliage treated with δ-endotoxin, and regular potato foliage on the flight of full-sib beetle families. Feeding on transgenic foliage had a strong negative effect on beetle flight. The beetles from the families that performed the longest flights when fed on regular foliage performed the shortest flights when fed on transgenic foliage. Laboratory experiments were conducted to compare relative fitness of beetle strains resistant and susceptible to δ-endotoxin. Net replacement rate, intrinsic rate of population increase, overwintering survivorship, and male mating capability were reduced for the resistant strain. Mortality, fecundity, and flight of the same strains were tested under laboratory conditions after beetles were fed on transgenic potato foliage, regular potato foliage, and regular potato foliage followed by transgenic foliage. Both strain and treatment had pronounced effects on the tested parameters, values for which decreased when the beetles were allowed to feed on regular foliage prior to a toxin ingestion.

Using controlled-release technology, a prototype novel biodegradable sphere, which is used for controlling apple maggot fly, Rhagoletis pomonella (Walsh), designed for long-lasting residual effectiveness of feeding stimulant and insecticide has been created. The sphere body consists of 42–50% sugar entrapped in a mixture of gelatinized corn flour and wheat flour in the presence of glycerin, and coated with a layer of latex paint containing insecticide. The sphere body serves as a slow-release sugar reservoir. First, the lethal and sublethal toxicity and the effects of tree sprays of the new insecticide imidacloprid on apple maggot flies were investigated. Females tested in the laboratory showed great mortality and reduced fecundity regardless of whether exposure was by oral or by surface contact. However, foliar sprays resulted neither in significant mortality nor reduced fecundity over a 7-day period. Secondly, technical-grade or formulated insecticides were incorporated in sphere coating mixtures and evaluated for acute toxicity and residual effectiveness in laboratory, semi-field and field experiments. Results indicated that imidacloprid is a promising substitute for dimethoate as a fly killing agent on spheres. A wettable powder formulation of imidacloprid (Merit) proved better than a flowable formulation (Provado) in terms of residual efficacy. Females feeding on imidacloprid-treated spheres exhibited very little tendency to forage within host plants or to lay eggs before dying, compared with females tested on dimethoate-treated spheres and control spheres. The sucrose pH shown to stimulate maximal feeding response was 6.4, with little feeding occurring at pH values of 5.0 or less and 8.0 or greater. Males were more responsive to varying pH than females. Such information is relevant to formulation improvements of coating mixtures of sucrose and insecticide applied to lethal spheres as part of tephritid fly control programs. (Abstract shortened by UMI.)

Thesis (Ph. D.)--Ohio State University, 2008.