In a series of studies conducted in Hawaii under seminatural conditions, we quantified the response of sexually mature, host‐seeking female melon flies, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae), to different types of visual and chemical host‐associated stimuli with the main aim of developing a monitoring device for females. Experiments were conducted using Tangletrap‐coated fruit mimics of either spherical (8 cm diameter) or cylindrical (4.3 cm diameter; 15 cm length) shapes coated with different artificial color pigments both at the ground level and at the tree‐canopy level so as to take into account the foraging behavior of adult melon flies. Females were particularly attracted to objects of spherical shape colored either yellow, white, or orange; these three pigments offered the highest reflectance values. Cucumber (Cucumis sativus L.) (Cucurbitaceae) odor was more attractive to females than odors of three other cultivated host fruit [zucchini, Cucurbita pepo L. var. medullosa Alef. (Cucurbitaceae); papaya, Carica papaya L. (Caricaceae); or tomato Solanum lycopersicum L. (Solanaceae)] or of ivy gourd [Coccinia grandis (L.) Voigt (Cucurbitaceae)], one of the major wild hosts of melon fly in Hawaii. A combination of both visual and olfactory stimuli was needed to elicit high levels of response compared to each stimulus offered alone. We discuss our results in relation to the potential implementation of improved female monitoring and/or attract‐and‐kill strategies for melon flies in Hawaii.

The effect of artificial and natural sources of adult food on the survival and reproduction of the tropical fruit fly, Anastrephaserpentina (Wiedemann) was studied. Caged adult flies were exposed during their whole lifespan to water and one of the following diets: sucrose, intact fruit, open fruit, bird faeces, sucrose plus intact fruit, sucrose plus open fruit, sucrose plus yeast hydrolysate, and sucrose plus bird faeces. All flies exposed to intact fruit or bird faeces died within the first five days of adult life without laying eggs. Females exposed to open fruit exhibited the greatest mean longevity (56.7 days). The highest net fecundity rate was recorded from individuals exposed to sucrose plus yeast hydrolysate (164 eggs per female), followed by those exposed to bird faeces plus sucrose and open fruit (38 and 26 eggs per female, respectively). Some individuals were able to lay viable eggs late in life (>105 days of age). Only populations in which adult flies had access to either sucrose plus yeast hydrolysate, open fruit, or sucrose plus bird faeces exhibited positive intrinsic rates of increase (r). Flies offered a combination of dry sucrose plus open fruit exhibited greatly reduced net fecundity levels when compared with those individuals exposed to open fruit. Even more significantly, populations of flies offered the combination of open fruit plus sucrose exhibited negative rates of increase while those exposed to open fruit alone, grew. We postulate that this reduction in egg production can be explained by a ‘junk food syndrome’.

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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. The distance over which a trap tree baited with such odor was effective in aggregating damage to fruit extended to at least 31-33 m (maximum evaluated) along a perimeter row. Trap trees at corners of orchard blocks were as effective as perimeter-row trap trees midway between corner trees. Within the canopy of a trap tree, damage did not tend significantly to be localized in the vicinity of the odor source but tended to be rather evenly distributed among various sectors of the canopy. Finally, among three candidate thresholds evaluated as a trigger for insecticide application, a threshold of one freshly injured fruit proved better than thresholds of two or four freshly injured fruit out of 50 fruit sampled on a trap tree in assuring that orchard-wide damage would remain below a preset economic injury level of 1%. Our findings lead us to suggest that after a whole-orchard application of insecticide to apple trees in Massachusetts orchards shortly after petal fall, subsequent applications of insecticide against plum curculio can be confined to peripheral-row trees and be driven by a provisional threshold of one freshly injured fruit out of 50 fruit sampled on a perimeter-row trap tree baited with the above-mentioned odor.

The apple maggot fly, Rhagoletis pomonella (Walsh), is a key pest of apple in eastern North America that has been historically controlled with organophosphate insecticide applications. Here we report on progress toward development of an effective and maintenance-free attracticidal sphere system for this pest species. In our studies, we evaluated lethality of spinosad in combination with a feeding stimulant (sucrose) to replace a Tangletrap sticky coating as the killing agent of a sphere-based behavioral control system. Spinosad was incorporated into cylindrical and contoured controlled-release caps that were fixed atop visually stimulating sphere bases. For both cap styles, spinosad at or near 1.0% (a.i.) proved to be a relatively durable fly-killing agent, providing approximately equal to 85% mortality after simulated rainfall exposure reflective of average season-long precipitation levels experienced during the primary period of risk of apple maggot injury to fruit in the northeastern United States. In field trials, we assessed the impact of color degradation of contoured controlled-release caps on visual responsiveness of apple maggot fly and found that it had no significant impact on captures. In commercial orchard trials designed to evaluate the potential of attracticidal spheres with contoured caps for direct control of apple maggot, a perimeter-based deployment provided protection comparable to plots receiving 1-2 whole-plot insecticide applications.

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Two new, comparatively safe insecticides (spinosad and imidacloprid) were compared with dimethoate (each at 1.5% active ingredient) for behavioural and mortality effects on Mexican fruit¯ies, Anastrepha ludens. Insecticide was mixed with sugar (as a feeding stimulant) and yellow latex paint (as an extending agent) applied to the surface of fruit-mimicking biodegradable 7 cm spheres made of sugar,¯our and glycerin. Flies feeding on spinosadtreated spheres did not differ from¯ies feeding on untreated spheres in post-feeding intra-tree¯ight capability, amount of oviposition or mortality. Flies that fed on imidacloprid-or dimethoate-treated spheres for as little as 30 s experienced both high reduction in oviposition and high mortality compared with¯ies that fed on untreated spheres, and the¯ies from imidacloprid-treated spheres also showed a much reduced intra-tree¯ight capability. If baited with attractive odour, biodegradable yellow spheres treated with a surface coating of imidacloprid in latex paint and sugar could have potential for suppressing Mexican fruit¯ies on host trees. U. S.