Effectiveness of odor-baited trap trees for plum curculio (Coleoptera: Curculionidae) monitoring in commercial apple orchards in the northeast.

The plum curculio, Conotrachelus nenuphar (Herbst), is a key pest of pome and stone fruit in eastern and central North America. For effective management of this insect pest in commercial apple (Malus spp.) orchards in the northeastern United States and Canada, one of the greatest challenges has been to determine the need for and timing of insecticide applications that will protect apple fruit from injury by adults.

Odor-baited trap trees: a novel management tool for plum curculio (Coleoptera: Curculionidae).

The plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), one of the most important pests of apple (Malus spp.) in eastern and central North America, historically has been managed in New England apple orchards by three full block insecticide applications. Efforts to reduce insecticide inputs against plum curculio include perimeter row sprays, particularly after petal fall, to control immigrating adults.

3 using odor-baited trap trees as sentinels to monitor plum curculio (Coleoptera: Curculionidae) in apple orchards.

In commercial orchards in Massachusetts in 2003, we conducted experiments aimed at developing guidelines for use of perimeter-row trap trees baited with grandisoic acid plus benzaldehyde as sentinels in a practical approach to determining need and timing of insecticide applications against overwintered plum curculios, Conotrachelus nenuphar (Herbst). Evaluations were based on percentages of sampled fruit injured by plum curculio. Trap trees baited with grandisoic acid released at approximately 1 mg/d plus benzaldehyde released at approximately 40 mg/d performed as well as or better than trap trees baited with greater or lesser amounts of these attractants in combination.

Field evaluation of plant odor and pheromonal combinations for attracting plum curculios.

The attractiveness of different synthetic host odors and a synthetic aggregation pheromone (grandisoic acid [GA]) to overwintered adult plum curculios (PCs), Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), was examined using two types of traps (sticky panels and black pyramids) placed in border areas surrounding an unsprayed section of an apple orchard in Massachusetts. In 2001, we evaluated the response of PCs to three synthetic fruit volatiles (benzaldehyde [BEN], ethyl isovalerate [EIV], and limonene [LIM]) assessed alone and in combination with GA, as well as the response to GA alone and a no-odor (control) treatment. BEN was the only host volatile that synergized the response of PCs to GA for both trap types.

Effectiveness of GF-120 fruit fly bait spray applied to border area plants for control of melon flies (Diptera: Tephritidae).

In a field study in Hawaii, color-marked protein-deprived and protein-fed female melon flies, Bactrocera cucurbitae Coquillett, were released within canopies of unsprayed sorghum plants (a nonhost of melon flies) outside of a border area of unsprayed or bait-sprayed sorghum plants or open space that surrounded cucumbers, a favored host of melon flies. Application of bait spray to sorghum or sugarcane surrounding host plants of melon flies is a common practice for melon fly control in Hawaii. GF-120 Fruit Fly Bait spray proved very effective in preventing protein-deprived females from alighting on cucumbers (23% of released females were observed dead on bait-sprayed sorghum; 0% were observed alive on cucumbers), but proved less effective in suppressing protein-fed females (14% of released females were observed dead on bait-sprayed sorghum; 11% were observed alive on cucumbers).

Odor-baited trap trees: a new approach to monitoring plum curculio (Coleoptera: Curculionidae).

We compared a trap approach with a trap-tree approach to determine the need and timing of insecticide applications against overwintered adult plum curculios, Conotrachelus nenuphar (Herbst.), in commercial apple orchards in Massachusetts in 2002. All traps and trap trees were baited with benzaldehyde (attractive fruit odor) plus grandisoic acid (attractive pheromone).

Effects of pH on feeding responses in the apple maggot fly, Rhagoletis pomonella (Diptera: Tephritidae).

Phagostimulatory effects of pH values of sucrose on Rhagoletis pomonella adults were studied in the laboratory. Flies were standardized for age, diet and food deprivation. Two presentation schemes were employed.

Response of plum curculio (Coleoptera: Curculionidae) to odor-baited traps near woods.

Response of overwintered plum curculios, Conotrachelus nenuphar (Herbst), to odor-baited traps was evaluated from the beginning until nearly the end of emigration from overwintering sites in woods. We evaluated clear sticky Plexiglas panels and black pyramid traps placed close to woods adjacent to apple trees in an unsprayed section of an orchard. Traps were baited with aggregation pheromone (grandisoic acid) alone or in combination with one of six synthetic fruit volatiles (benzaldehvde, decyl aldehyde, E-2-hexenal, ethyl isovalerate, hexyl acetate, or limonene).

Comparison of neonicotinoid insecticides for use with biodegradable and wooden spheres for control of key Rhagoletis species (Diptera: Tephritidae).

Field-based studies and laboratory bioassays were conducted with apple maggot, Rhagoletis pomonella (Walsh), and blueberry maggot, Rhgoletis mendax Curran, flies to investigate the performance and duration of activity of insecticide-treated biodegradable and wooden spheres for control of Rhagoletis species. Four neonicotinoid insecticide treatments including imidacloprid, thiamethoxam, and thiocloprid at 2% (AI) were evaluated with biodegradable spheres. In 1999, significantly more apple maggot flies were found killed by imidacloprid-treated spheres compared with thiamethoxam-treated spheres during early and late season.

Evaluation of individual components of plum odor as potential attractants for adult plum curculios.

We evaluated olfactory attraction of overwintered plum curculio (PC) adults, Conotrachelus nenuphar, to 16 individual volatile components of unripe plum odor in the laboratory using a still-air dual-choice bioassay system and in the field using baited cotton dental wicks attached to boll-weevil traps placed on the ground beneath the canopy of unsprayed apple trees. Two compounds, ethyl isovalerate and limonene, were significantly attractive in both laboratory bioassays and field experiments. In laboratory bioassays, as concentration was decreased across five orders of magnitude, a greater number of compounds elicited responses suggestive of attractancy (except at the lowest concentration).

Joining and avoidance behavior in nonsocial insects.

Groups of two or more consexual conspecific adults of many kinds of nonsocial insects have been observed to form at feeding, mating, ovipositional, or sheltering sites. Conversely, adults of these same insects have been observed to avoid joining consexual conspecifics (or their progeny) and to place themselves (or their progeny) at some distance that results in spacing. Examples from various taxa illustrate that mechanisms underlying joining or avoidance behavior differ among species, as do types of benefits and costs to individuals who decide to join or avoid others.

Attraction of apple maggot flies, Rhagoletis pomonella (Diptera: tephritidae) of different physiological states to odour-baited traps in the presence and absence of food.

Adults of apple maggot fly Rhagoletis pomonella (Walsh) of differing physiological states were marked and released in blocks of apple trees ringed by sticky red spheres. Spheres were either unbaited, baited with butyl hexanoate (synthetic host fruit odour) or baited with both butyl hexanoate and ammonium carbonate (synthetic food odour). All trap and lure treatments were compared in the presence or absence of food (bird faeces) in the blocks.

Toxicity and residual effectiveness of insecticides on insecticide-treated spheres for controlling females of Rhagoletis pomonella (Diptera: Tephritidae).

This study evaluated the toxicity of five technical-grade insecticides of four different classes to apple maggot females, Rhagoletis pomonella (Walsh), following a 10-min exposure period in insecticide-coated glass jars, with or without a feeding stimulant (sucrose) present. According to LC90 values for toxicity by ingestion and tarsal contact, imidacloprid was 1.5 times more toxic than dimethoate or abamectin, diazinon was less toxic, and phloxine B (a phototoxic dye) least toxic.

Attraction of adult Rhagoletis indifferens (Diptera: Tephritidae) to unbaited and odor-baited red spheres and yellow rectangles.

Five sizes of red spheres (4, 6, 8, 10, and 12 cm diameter) and 2 orientations of yellow rectangles (vertical and V) were evaluated as unbaited sticky-coated traps for western cherry fruit flies, Rhagoletis indifferens Curran, in unmanaged cherry trees in Washington and Oregon. Red spheres that were 10 cm in diameter attracted more flies than red spheres that were 8 or 12 cm in diameter and significantly more flies than 4- or 6-cm spheres and yellow rectangles of either orientation. In a 2nd test, red spheres (10 cm diameter) baited with ammonium carbonate alone or ammonium carbonate plus putrescine attracted significantly more R.

Controlled release of sugar and toxicant from a novel device for controlling pest insects.

A novel biodegradable device, designed for long-lasting residual effectiveness of feeding stimulant (sugar) and insecticide (dimethoate) against apple maggot files and other insects, was formulated. The device is an 8-cm diameter fruit-mimicking sphere, consisting 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 dimethoate and sugar. We found that the outer layer of paint prevents cracking of the sphere upon drying and creates a barrier to control the release of both sugar and dimethoate.

Attraction ofCeratitis capitata (Diptera: Tephritidae) flies to odor of coffee fruit.

On potted nonfruiting host trees in outdoor field cages, we evaluated attraction of released mature laboratory-cultured or wild-origin Mediterranean fruit flies (medflies) to odor of freshly picked fruit of host and nonhost plants. Odor of ripe intact or crushed coffee fruit (the presumed ancestral host of medflies) was significantly more attractive than odor of ripe intact or crushed fruit of five lower-ranking hosts and three nonhosts. Odor of crushed coffee fruit was significantly more attractive than odor of intact coffee fruit.

Bioassay approaches to assessing behavioral responses of plum curculio adults (Coleoptera: Curculionidae) to host fruit odor.

We evaluated several approaches to developing a simple, sensitive, and reliable laboratory bioassay of responses of overwintered adult plum curculios (PCs),Conotrachelus nenuphar (Herbst), to host fruit odor or its attractive components. A high proportion of assayed PCs responded positively to odor of wild plums under no-choice, moving-air conditions in a wind tunnel and under dual-choice, still-air conditions in enclosed Petri dishes. Positive response to controls lacking host odor, however, was much greater in the wind tunnel, arguing in favor of bioassays under dual-choice conditions in still air to provide greater PC discrimination.

Distance of response to host tree models by female apple maggot flies,Rhagoletis pomonella (Walsh) (Diptera: Tephritidae): Interaction of visual and olfactory stimuli.

Mature female apple maggot flies,Rhagoletis pomonella (Walsh), were released individually onto a single potted, fruitless hawthorne tree in the center of an open field. The tree was surrounded by four 1-m(2) plywood host tree models painted green or white, with or without synthetic host fruit odor (butyl hexanoate), and placed at one of several distances from the release tree. Each fly was permitted to forage freely on the release tree for up to 1 hr, or until it left the tree.

Host odor and visual stimulus interaction during intratree host finding behavior ofRhagoletis pomonella flies.

Responses ofRhagoletis pomonella (Walsh) (Diptera: Tephritidae) flies to host fruit visual stimuli (apples or models of apples) and chemical stimuli (synthetic apple volatile blend) were studied in semidwarf field-caged apple trees. Three different fruit or model densities (1, 4, or 16 fruit or models/ tree) and two odor release rates [ca. 0.

The effect of short-range host odor stimuli on host fruit finding and feeding behavior of plum curculio adults (Coleoptera: Curculionidae).

In laboratory assays, we investigated responses of female plum curculios (PCs),Conotrachelus nenuphar (Herbst), to host and nonhost fruit or leaf odor when PCs were crawling on experimental tree branchlets or twigs. In choice tests where test specimens were hung from the ends of a wooden crosspiece, PCs made significantly more visits to host plum fruit than to plum leaves, nonhost tomato fruit, wax models of plum fruit, or blanks (wire). In similar tests, PCs made significantly more visits to plum leaves compared to nonhost maple leaves or to blanks.

Effect of physiological and experiential state ofBactrocera tryoni flies on intra-tree foraging behavior for food (bacteria) and host fruit.

Using caged host trees on which we manipulated food and oviposition sites, we investigated the foraging behavior of individually-releasedBactrocera tryoni (Diptera: Tephritidae) females in relation to state of fly hunger for protein, presence or absence of bacteria as a source of protein, degree of prior experience with host fruit, and quality of host fruit for oviposition. One aim was to evaluate whether it is immature or matureB. tryoni females that are responsible for initially inoculating host fruit surfaces with "fruit-fly-type" bacteria, the odor of which is known to attractB.

Sex differences in movement between natural feeding and mating sites and tradeoffs between food consumption, mating success and predator evasion in Mediterranean fruit flies (Diptera: Tephritidae).

Systematic quantitative observations of the location and diel pattern of adult Mediterranean fruit fly, Ceratitis capitata (Wiedemann), activities were carried out in an orange grove and surroundings on the island of Chios in Greece. Natural fly foods were assessed for their contribution to fly longevity, fecundity and fertility. There were diel shifts in male and female location.

The effect of prior adult experience on components of habitat preference in the apple maggot fly (Rhagoletis pomonella).

Numerous authors have suggested that genetic subdivision within a population in a heterogeneous environment is more likely if individuals tend, through prior experience, to breed in the same habitat in which they developed. Under semi-field conditions we demonstrate that prior adult experience alters habitat preference in the apple maggot fly, Rhagoletis pomonella (Tephritidae), a frugivorous parasitic insect thought to have undergone sympatric divergence in host use in historical times. Females exposed to a particular host fruit species - apple (Malus pumila) or hawthorn (Crataegus mollis) - in a field cage oviposited at a higher rate in test fruit of that species than did inexperienced females or females exposed to the other species.

Behavioral evidence for host races in Rhagoletis pomonella flies.

One of the most controversial putative cases of host race formation in insects is that of the apple maggot fly, Rhagoletis pomonella (Diptera: Tephritidae). A principal cause of the controversy is lack of relevant data. In laboratory and field enclosure experiments, we compared the host acceptance behavior of sympatric populations of flies originating from naturally infested hawthorn (the native host) and apple (an introduced host) in Amherst, Massachusetts or East Lansing, Michigan.