Improving the selectivity of water traps for monitoring populations of the cabbage root fly

Traps placed within brassica crops to monitor changes in cabbage root fly activity could be made more selective by painting black the inner wall of the standard fluorescent yellow water-traps. Traps could also be made more selective by covering them with cylinders of Netlon mesh, although this procedure reduces the numbers of cabbage root fly caught by about 70%. Of the single-coloured traps tested, those painted “marigold” yellow were the most selective in capturing female cabbage root flies. Although white and certain blue traps were as effective as the best yellow traps at capturing cabbage root flies, such traps should be avoided, as they catch 4–5 times as many of the closely-related bean seed fly. The presence of bean seed flies makes cabbage root fly identification more difficult and adds considerably to the time required to sort trap catches.     

Winter feeding sites of hay in round bales as major developmental sites of Stomoxys calcitrans (Diptera: Muscidae) in pastures in spring and summer

The stable fly, Stomoxys calcitrans (L.), historically has been a pest of livestock in confined operations but seldom of animals on pastures or rangelands. In the past two decades, however, S. calcitrans has become a major pest of cattle and horses on pastures in the midwestern United States. Although there usually is an overabundance of diverse stable fly and house fly, Musca domestica L., larval habitats in confined livestock operations, no larval habitat for stable flies has been clearly identified in the pasture-range environment. Because the winter feeding of hay in round bales results in significant amounts of hay wastage that when mixed with manure, might develop into suitable larval habitats, this study evaluated these areas as developmental sites for the abundant stable flies in pastures. There was a trend for fly traps placed in the vicinity of hay feeding sites to catch more stable flies than those placed distant from these sites. Estimates of stable flies emerging from these sites ranged from 102 to 1225 flies per core sample (25 by 25 cm). The mean number of adult stable flies during May and June 2001 through 2004 correlated negatively with the average minimum temperatures during the preceding winter (November-February) but not with rainfall or temperatures during the spring. These results support the hypothesis that winter feeding sites of hay in round bales are the main source of stable flies in pastures.     

The fly factor phenomenon is mediated by interkingdom signaling between bacterial symbionts and their blow fly hosts

We tested the recent hypothesis that the"fly factor"phenomenon(food cur-rently or previously fed on by flies attracts more flies than the same type of food kept inccessible to flies)is mediated by bacterial symbionts deposited with feees or regur-gitated by feeding flies.We allowed laboratory-reared black blow flies,Phormia regina(Meigen),to feed and de fecate on bacterial Luria-Bertani medium solidified with agar,and isolated seven morphologically distinct bacterial colonies.We identified these us-ing matrix-assisted laser desorption/ionization mass spectrometry and sequencing of the 165 rRNA gene.In two-choice laboratory experiments,traps baited with cultures of Pro-teus mirabilis Hauser,Morganella morganii subsp.sibonii Jensen,or Serratia marcescens Bizio,captured significantly more flies than corresponding control jars baited with tryptic soy agar only.A mixture of seven bacterial strains as a trap bait was more attractive to flies than a single bacterial isolate(M.m.siboni).In a field experiment,traps baited with agar cultures of P:mirabilis and M.m siboni in combination captured significantly more flies than lraps baited with either bacterial isolate alone or the agar control.As evident by gas chromatography-mass spectrometry,the odor profiles of bacterial isolates differ,which may explain the additive effect of bacteria to the attractiveness of bacterial trap baits.As"generalist bacteria,"P mirabilis and M.m.sibonii growing on animal protein(beef liver)or plant protein(tofu)are similarly effective in attracting flies.Bacteria-derived airborne semiochemicals appear to mediate foraging by flies and to inform their feeding and oviposition decisions.     

Behavioural responses of stable flies to cattle manure slurry associated odourants

Stable flies (Stomoxys calcitrans [Diptera: Muscidae] L.) are blood‐feeding synanthropic pests, which cause significant economic losses in livestock. Stable fly antennae contain olfactory sensilla responsive to host and host environment‐associated odours. Field observation indicated that the abundance of stable flies increased significantly in grasslands or crop fields when cattle manure slurry was applied. Major volatile compounds emanating from manure slurry were collected and identified. Behavioural responses of stable flies to those compounds were investigated in laboratory bioassays and field‐trapping studies. Results from olfactometer assays revealed that phenol, p‐cresol and m‐cresol were attractive to adult stable flies. When tested individually, attraction was higher with lower dosages. Stable flies were most attracted to blends of phenol and m‐cresol or p‐cresol. Traps with binary blend lures caught more stable flies in field trials as well.     

Volatile host fruit odors as attractants for the oriental fruit fly (Diptera: Tephritidae)

We examined the responses of oriental fruit flies, Bactrocera dorsalis Hendel, to the odors of different stages and types of fruit presented on potted trees in a field cage. Females were most attracted to odors of soft, ripe fruit. Odors of common guava were more attractive to females than papaya and starfruit, and equally as attractive as strawberry guava, orange, and mango. In field tests, McPhail traps baited with mango, common guava, and orange captured equal numbers of females. Traps baited with mango were compared with 2 commercially available fruit fly traps. McPhail traps baited with mango captured more females than visual fruit-mimicking sticky traps (Ladd traps) and equal numbers of females as McPhail traps baited with protein odors. Results from this study indicate that host fruit volatiles could be used as lures for capturing oriental fruit flies in orchards.     

Comparative attraction of four different fiberglass traps to various age and sex classes of stable fly (Diptera: Muscidae) adults

An Alsynite cylinder trap and three different Williams cross-configuration traps with three adhesives were compared to determine their relative attraction to stable fly, Stomoxys calcitrans (L.), adults. Williams traps coated with Olson Sticky Stuff performed as well as Williams traps coated with Tack Trap, thus allowing fly samples collected with either adhesive to be compared. The cylinder trap captured fewer total flies, but more flies per cm2 than any of the Williams traps. Sex ratio of flies captured on the cylinder trap was 50:50, while the three Williams traps captured predominantly males. The cylinder trap captured a larger percentage of nulliparous, unmated females than did the other traps tested.     

Interaction between natural and synthetic fruit odor influences response of apple maggot flies to visual traps

In order to improve perimeter trapping for apple maggot fly behavioral control, we designed a set of experiments which aimed to reach a better understanding of the nature of the interaction between the natural host odor released by susceptible and low‐susceptibility apple cultivars, and an artificial host odor currently employed as a lure along with visual traps for apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), perimeter trapping programs. The response of apple maggot flies to lured and unlured visual traps deployed in different rectangular arrays of susceptible and low‐susceptibility apple cultivars (two central trees of a particular cultivar surrounded by four perimeter trees of the same or a different cultivar) was evaluated over 2 years under field conditions. In uniform blocks of susceptible (Tidemann Red, Jersey Mac) or low‐susceptibility (Marshall McIntosh) cultivars, lured traps recovered a significantly greater proportion of the total capture than unlured traps, irrespective of lure position (center or perimeter trees). Unlured traps on central susceptible apple cultivars (Red Astrachan, Gala, Fuji) recovered a significantly greater proportion of the total capture than unlured traps on surrounding low‐susceptibility cultivars (Marshall McIntosh, Paula Red, Red Delicious, and Golden Delicious). Placing the lures near traps on low‐susceptibility cultivar trees surrounding unlured traps on central susceptible cultivar trees reduced apple maggot fly visits to traps on central trees, but the latter still recovered a similar proportion of the total capture as lured traps on perimeter trees. By contrast, placing the lures near traps on central susceptible cultivar trees surrounded by unlured traps on low‐susceptibility cultivar trees allowed lured central traps to receive a significantly greater proportion of the total capture than unlured perimeter traps. We conclude that the synthetic and natural host odor of susceptible cultivars interact additively in attracting apple maggot flies to visual traps, and that, when given the choice, traps and lures should be deployed on preferred rather than on less preferred cultivar trees. Implications for trap deployment strategies for tephritid monitoring and control are discussed in the light of our findings.     

Evaluation of commercial and field‐expedient baited traps for house flies,Musca domestica L. (Diptera: Muscidae)

A comparison of nine commercial baited fly traps on Florida dairy farms demonstrated that Terminator traps collected significantly more (13,323/trap) house flies (Musca domestica L.) than the others tested. Final Flight, Fly Magnet, and FliesBeGone traps collected intermediate numbers of flies (834‐2,166), and relatively few were caught with ISCA, Advantage, Fermone Big Boy, Squeeze & Snap, or OakStump traps (<300). Terminator traps collected about twice as many flies (799.8/trap) as FliesBeGone traps (343.8) when each trap was baited with its respective attractant, but when the attractants were switched between the two trap types, collections were significantly lower (77‐108) than was observed with traps baited with their respective attractant. Solutions of molasses were significantly more attractive to house flies than honey, maple syrup, or jaggery (date palm sugar). Field‐expedient traps constructed from discarded PET water bottles were much less effective than commercial traps, but painting the tops of such traps with black spray paint resulted in a six‐fold increase in trap capture.     

Attraction of Bactrocera dorsalis (Diptera: Tephritidae) and nontarget insects to methyl eugenol bucket traps with different preservative fluids on Oahu Island, Hawaiian Islands

Attraction of oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), and nontarget insects to preservative fluids ethylene glycol antifreeze, propylene glycol antifreeze, or mineral oil in bucket traps that contained captured decaying male oriental fruit flies, a male lure (methyl eugenol), and a toxicant (DDVP vapor insecticidal strip) were compared with dry control traps. Significantly (P < 0.05) greater numbers of B. dorsalis were captured in propylene glycol antifreeze traps than in other attractant trap types. Among attractant trap types with lowest negative impacts on nontarget insects, control traps captured significantly lower numbers of three species and one morphospecies of scavenger flies, one species of plant-feeding fly, and one species each of sweet-and lipid-feeding ants. Mineral oil traps captured significantly lower numbers of two species of scavengers flies and one morphospecies of plant-feeding fly, and one species of sweet-feeding ant. Because of the fragile nature of endemic Hawaiian insect fauna, the propylene glycol antifreeze bucket trap is best suited for use in environments (e.g., non-native habitats) where endemic species are known to be absent and mineral oil traps are more suited for minimizing insect captures in environmentally sensitive habitats.     

Stable fly, Stomoxys calcitrans, mouthpart removal influences stress and anticipatory responses in mice

Abstract Biting fly attack induces a variety of stress and anxiety related changes in the physiology and behaviour of the target animals. Significant reductions in pain, or more appropriately, nociceptive sensitivity (latency of a foot-lifting response to an aversive thermal stimulus), are evident in laboratory mice after a 1 h exposure to stable flies, Stomoxys calcitrans. The role of the various components of biting fly attack in the development of this stress-induced reduction in pain sensitivity (analgesia) is, however, unclear. This study demonstrates that fly-naive mice do not exhibit a stress-induced analgesia when exposed to stable flies whose biting mouthparts have been removed. In contrast, mice that have been previously exposed to intact stable flies exhibit significant analgesia when exposed to flies that are incapable of biting. However, the level of analgesia induced is lower than that elicited by exposure to intact stable flies. Exposure to non-biting house flies, Musca domestica , has no effect on nociceptive sensitivity. It appears that the actual bite of the stable fly is necessary for the induction of analgesia and probably other stress and anxiety associated responses in fly naive mice. However, mice rapidly learn to recognize biting flies and exhibit significant, possibly anticipatory analgesic responses to the mere presence of biting flies.     

Exposure to stable flies reduces spatial learning in mice: involvement of endogenous opioid systems

Abstract. Biting flies influence both the physiology and behaviour of domestic and wild animals. This study demonstrates that relatively brief (60min) exposure to stable flies, Stomoxys calcitrans (L.), affects the spatial abilities of male mice. Stable fly exposure resulted in poorer subsequent performance in a water maze task in which individual mice had to learn the spatial location of a submerged hidden platform using extramaze visual cues. Determinations of spatial acquisition and retention were made with mice that had been previously exposed for 60min to either stable flies or house flies, Musca domestica (L.). Mice exposed to stable flies displayed over one day of testing (six blocks or sets of four trials) significantly poorer acquisition and retention of the water maze task than either mice that had been exposed to house flies or fly-naive mice. This attenuation of spatial learning occurred in the absence of any evident sensorimotor or motivational impairments. The reduction in spatial abilites involved endogenous opioid systems, as the decreased performance resulting from stable fly exposure was blocked by pre-treatment with the prototypic opiate antagonist, naltrexone. These results indicate that relatively brief exposure to biting flies can lead to a decrease in spatial abilities which is associated with enhanced endogenous opioid activity. These results support the involvement of endogenous opioid systems in the mediation of the behavioural and physiological effects of biting fly exposure. They further suggest that decreases in spatial abilities and performance may be part of the behavioural consequences of biting fly exposure in domestic and wild animals.     

Characterization of olfactory sensilla of Stomoxys calcitrans and electrophysiological responses to odorant compounds associated with hosts and oviposition media

Stable flies, Stomoxys calcitrans L. (Diptera: Muscidae), are economically important biting flies that have caused billions of dollars in losses in the livestock industry. Field monitoring studies have indicated that olfaction plays an important role in host location. To further our understanding of stable fly olfaction, we examined the antennal morphology of adults using scanning electron microscopy techniques. Four major types of sensillum were found and classified as: (a) basiconic sensilla; (b) trichoid sensilla with three subtypes; (c) clavate sensilla, and (d) coeloconic sensilla. No significant differences between male and female flies in abundances (total numbers) of these sensillum types were observed, except for medium-sized trichoid sensilla. The distinctive pore structures found on the surface of basiconic and clavate sensilla suggest their olfactory functions. No wall pores were found in trichoid and coeloconic sensilla, which suggests that these two types of sensillum may function as mechano-receptors. Details of the distributions of different sensillum types located on the funicle of the fly antenna were also recorded. Electroantennogram results indicated significant antennal responses to host-associated compounds. The importance of stable fly olfaction relative to host and host environment seeking is discussed. This research provides valuable new information that will enhance future developments in integrated stable fly management.     

Walk-through trap for control of horn flies (Diptera: Muscidae) on pastured cattle

A walk-through fly trap designed in 1938 by W. G. Bruce was tested for two field seasons in Missouri. Screened elements along both sides of the device functioned as cone traps, thereby catching horn flies, Haematobia irritans (L.), as they were swept from cattle by strips of carpet hung from the roof. Horn fly control on pastured cattle averaged 54 and 73% when they were afforded access to the trap. Analyses of Diptera captured in the trap indicated that horn flies comprised the most abundant species; face flies, Musca autumnalis De Geer, stable flies, Stomoxys calcitrans (L.), and others were present in smaller numbers. Cattle were not reluctant to use the trap, and no structural problems were observed during the experiment.     

Stable fly (Stomoxys calcitrans: Diptera, Muscidae) trap response to changes in effective trap height caused by growing vegetation

Stable flies (Stomoxys calcitrans L.) are blood-feeding pests of cattle, whose populations are often monitored using sticky traps. Trap responses at different heights were compared with: 1) a choice and no-choice test, with sticky cards set at 30 and 121 cm heights (above ground), and 2) tall (120 cm) traps placed in short (3 cm) and tall (40 cm) grass to assess how vegetation height affects trap catches. In the first experiment, the percentage of upper to lower trap catches were similar at choice (16%) and no-choice traps (15%). In the vegetation study, stable fly catch height data were fitted to gamma distributions to determine the most productive trap heights; 20 cm above short grass and 24 cm above tall grass (from lower edge of trap). The results indicate that traps used to monitor stable fly populations should be maintained at a constant distance above surrounding vegetation rather than ground surface, otherwise trap data can be misleading.     

Cues used by the black fly,Simulium annulus,for attraction to the common loon (Gavia immer)

The parasitic relationship between a black fly, Simulium annulus, and the common loon (Gavia immer) has been considered one of the most exclusive relationships between any host species and a black fly species. To test the host specificity of this blood‐feeding insect, we made a series of bird decoy presentations to black flies on loon‐inhabited lakes in northern Wisconsin, U.S.A. To examine the importance of chemical and visual cues for black fly detection of and attraction to hosts, we made decoy presentations with and without chemical cues. Flies attracted to the decoys were collected, identified to species, and quantified. Results showed that S. annulus had a strong preference for common loon visual and chemical cues, although visual cues from Canada geese (Branta canadensis) and mallards (Anas platyrynchos) did attract some flies in significantly smaller numbers.     

Monitoring populations of the carrot fly, Psila rosae, with sticky and water traps

The relative, effectiveness of Rebell®, small cylinder, large cylinder, windmill and water traps, the five types of trap used currently for monitoring populations of the carrot fly, Psila rosae, was assessed in nine field experiments, three in south west Lancashire, four in the Fens (Suffolk, Norfolk, Cambridgeshire), one in East Suffolk and one at Wellesbourne, Warwickshire. Regression analysis of the numbers of flies caught on each type of trap against the numbers caught on the Rebell® trap indicated that each trap samples a constant proportion of the fly population relative to the other traps. Therefore, provided the fly population was sufficiently large for insects to be caught on the least effective traps, any of the five traps would monitor adequately fluctuations in carrot fly populations. However, the Rebell® trap caught 4–17 times as many flies/trap and 5–7 times as many flieshnit area of trap as any of the other traps tested.
Operators considered the Rebell® trap to be the easiest to use. However, it was more expensive than any of the other traps tested.     

Capture of Mediterranean fruit flies (Diptera: Tephritidae) in dry traps baited with a food-based attractant and Jackson traps baited with trimedlure during sterile male release in Guatemala

Captures of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in Jackson traps baited with trimedlure were compared with captures in cylindrical open-bottom dry traps baited with a food-based synthetic attractant (ammonium acetate, putrescine, and trimethylamine). Tests were conducted in Guatemala during a sterile male release program in an area where wild flies were present in low numbers. More wild and sterile females were captured in food-based traps, and more wild and sterile males were captured in trimedlure traps. The food-based traps captured almost twice as many total (male plus female) wild flies as the trimedlure traps, but the difference was not significant. Females made up approximately 60% of the wild flies caught in the food-based attractant traps; the trimedlure traps caught no females. The ratio of capture of males in trimedlure traps to food-based traps was 6.5:1 for sterile and 1.7:1 for wild flies. Because fewer sterile males are captured in the food-based traps, there is a reduction in the labor-intensive process of examining flies for sterility. The results indicate that traps baited with food-based attractants could be used in place of the Jackson/trimedlure traps for C. capitata sterile release programs because they can monitor distributions of sterile releases and detect wild fly populations effectively; both critical components of fruit fly eradication programs by using the sterile insect technique.     

Spatio‐temporal distribution of Ceratitis capitata population in a heterogeneous landscape in Central Italy

The spatio‐temporal dynamics of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), was investigated to evaluate the effect of the landscape elements and host plants on pest distribution, in an agricultural landscape of 500 ha located in Central Italy. Two farms (farm 1 and farm 2) are located in the experimental area, composing mixed fruit orchards and surrounded by hedgerows, small woodlots, private gardens and cereal fields. Ceratitis capitata population fluctuation was monitored, from 2006 to 2008, using traps baited with trimedlure. Geostatistical methods such as Inverse distance squared weighted were used to obtain distributional maps of adults, mainly males. Results showed that the adult Mediterranean fruit flies were primarily distributed inside farm 1, with the maximum density found in the months of September and October. Away from the principal host plants, particularly in cereal fields, the number of trapped individuals was always low or zero. In both farms, flies were caught sequentially in traps located on host plants (i.e. peach, apple, pear, oriental persimmon and prickly pear) at varying times of maturation, especially when fruits remained on the trees. Distributional maps provided evidence that allowed to identify habitats in which the fly developed early in the season (mixed peach orchards) and afterwards during the periodic flights.     

Studying the “fly factor” phenomenon and its underlying mechanisms in house flies Musca domestica

The “fly factor” was first discovered >60 years ago and describes the phenomenon that food currently or previously fed on by flies attracts more foraging flies than the same type and amount of food kept inaccessible to flies. Since then, there has been little progress made to understanding this phenomenon. Our objectives were (i) to demonstrate the existence of the fly factor in house flies, Musca domestica and (ii) to study underlying mechanisms that may cause or contribute to the fly factor. In 2‐choice laboratory bioassays, we obtained unambiguous evidence for a fly factor phenomenon in house flies, in that we demonstrated that feeding flies are more attractive to foraging flies than are nonfeeding flies, and that fed‐on food is more attractive to foraging flies than is “clean” food. Of the potential mechanisms (fly excreta, metabolic output parameters [elevated temperature, relative humidity, carbon dioxide]), causing the fly factor, fly feces, and regurgitate do attract foraging flies but none of the metabolic output parameters of feeding flies does. Even though feeding flies produce significantly more CO₂ than nonfeeding flies, elevated levels of CO₂ have no behavior‐modifying effect on flies. Preferential attraction of house flies to fly feces and regurgitate indicates that the flies sense airborne semiochemicals emanating from these sources. Hypothesizing that these semiochemicals are microbe‐produced, future studies will aim at isolating and mass producing these microbes to accumulate semiochemicals for identification.