Trivial Flight Research Articles

Cabbage whiteflies colonise Brassica vegetables primarily from distant, upwind source habitats

AbstractThe occurrence of species in rapidly changing environments, such as agricultural landscapes, is affected by their ability to recolonise habitats. Knowledge of the landscape scale affecting colonisation is essential for large‐scale pest management. Colonisation by insects can be affected on multiple landscape scales, as different morphs of a species may have specific dispersal abilities. The cabbage whitefly, Aleyrodes proletella (L.) (Hemiptera: Aleyrodidae), a major pest of Brassica vegetables, is known to colonise Brassica vegetables primarily from fields of oilseed rape, Brassica napus L. (Brassicaceae). We used field mapping and remote sensing to characterise the relevant scales for colonisation of Brussels sprouts by cabbage whiteflies. Surprisingly, oilseed rape fields in wide landscapes (2–8 km around study sites) explained colonisation better than oilseed rape areas in local landscapes (200–1 000 m around study sites). The explained variance increased when additional weight was given to upwind source habitats, indicating wind transport of whitefly colonisers. Low importance of local compared to wide landscape source habitats can be explained by the flight behaviour of whitefly morphs. Migratory morphs show phototactic attraction but are attracted by hosts only during the later phases of flight. Therefore, they ignore host plants close to their origin and disperse several kilometres. Trivial flight morphs rarely move more than a few hundred metres. In conclusion, as most whitefly colonisers reached Brassica vegetables from source habitats at a distance of 2–8 km, predictions on pest pressure and landscape‐scale whitefly management should consider these distances. In contrast, oilseed rape fields in the local landscape, which usually worry farmers, had little effect.

Flight Behavior of Methyl-Parathion-Resistant and -Susceptible Western Corn Rootworm (Coleoptera: Chrysomelidae) Populations from Nebraska

Relative flight behavior of methyl-parathion-resistant and -susceptible western corn rootworm, Diabrotica virgifera virgifera LeConte populations, was studied as part of a larger effort to characterize the potential impact of insecticide resistance on adult life history traits and to understand the evolution and spread of resistance. A computer interfaced actograph was used to compare flight of resistant and susceptible individuals, and flight of resistant individuals with and without prior exposure to methyl-parathion. In each case, mean trivial and sustained flight durations were compared among treatments. In general, there were few differences in trivial or sustained flight characteristics as affected by beetle population, insecticide exposure, sex, or age and there were few significant interactions among variables. Tethered flight activity was highly variable and distributions of flight duration were skewed toward flights of short duration. Tethered flight activity was similar among resistant and susceptible beetles with the exception that susceptible beetles initiated more flights per beetle than resistant beetles. After sublethal exposure to methyl-parathion, total flight time, total trivial flight time, and mean number of flights per resistant beetle declined significantly. Because long-range flight was uncommon, short- to medium-duration flights may play an important role in determining gene flow and population spread of resistant D. v. virgifera. These results suggest that organophosphate-resistant beetles can readily move and colonize new areas, but localized selection pressure (e.g., management practices) and exposure to methyl-parathion may contribute to the small-scale differences in resistance intensity often seen in the field.

Flight potential and oxygen uptake during early dormancy in Coccinella septempunctata

AbstractTwo flight parameters (take‐off and duration) and respiration level were measured, in two years in summer and early autumn, in dormant Coccinella septempunctata L. (Coleoptera: Coccinellidae) collected while hidden in grass tussocks in hibernation sites (HID) and in beetles collected on plants (PLA). The duration of tethered flight of HID beetles measured in the laboratory in late August and September 1995 (range of geometric means 190–440 s) was slightly longer than the flight of PLA beetles (80–310 s), both being much longer than trivial flight recorded in beetles foraging for prey during the breeding season (35 s). In general, the flight performance had a tendency to increase in September and to decrease in October.The oxygen consumption in HID beetles increased throughout September 1994 from 430 to 780 μl g−1 h−1 and throughout October 1995 from 710 to 1060 μl g−1 h−1. This increase is ascribed to a concomitant decrease in diapause intensity. A similar increase was observed also in PLA beetles in 1994 and oxygen consumption was always higher than in HID beetles, most probably due to feeding and digestion in PLA beetles.Laboratory feeding of HID beetles on aphids induced maturation of ovaries and increased oxygen uptake (from 680 to 1110 μl g−1 h−1). Feeding on honey and pollen left their oxygen uptake unchanged. Effect of feeding on the flight parameters was mostly not significant. In agreement with its less suitable body shape and usually less distant dormancy sites, C. septempunctata was found a less apt flier than long‐distance migrating coccinellid species.

Rate of spread of PVYn by alateMyzus persicae (Sulzer) from infected to healthy plants under laboratory conditions

Alate green peach aphids,Myzus persicae (Sulzer), tested in a flight chamber during their maiden flight period displayed behaviours ranging from repeated trivial flights to settling on the plants. The interaction of alate vector density and PVYn spread was dichotomous, virus spread was significantly related to vector density in some trials but virus spread was nil or limited and not significantly dependent on vector density in others. The green peach aphid colony used in these experiments provided a mixture of active and highly active alate populations. Results suggest that inactive and active vectors came from the active and highly active alate populations, respectively. Therefore, winged aphids within a species cannot all be attributed the same vector efficiency unless known to originate from the same population. At a 15% inoculum level the intercept for the regression model for the spread of PVYn was 5.03% indicating that there is a significant probability of propagation at aphid densities as low as one. However, over the range of aphid densities tested, the rate of spread per aphid was low, 0.08%, suggesting that reinfection of newly infected plants or movement interference between aphid vectors rapidly became important factors negatively affecting virus spread. Although these results cannot be directly transferred to field conditions they provide confirmation that lowM. persicae numbers can transmit unacceptable levels of mosaic and that low inoculum levels are required to decrease the risk of transmission by the small aphid numbers which cannot be realistically controlled.

Effect of trap background on cabbage root fly landing and capture

AbstractPieces (600 mm × 800 mm) of coloured board, plastic sheeting and woven materials, placed beneath water traps prevented the traps from becoming soiled during rainy weather. Such backgrounds are not recommended for use with traps for monitoring populations of the cabbage root fly (Delia radicum L. ‐ Diptera:Anthomyiidae), however, as, instead of increasing trap catch they reduced the numbers of female flies caught by 70%–90%. The main effect was that the visually attractive stimuli from the introduced backgrounds competed with those from the trap. A white background competed with a white trap on a direct fly/unit area basis. Green backgrounds stimulated males to land and the vertical stems of both real and artificial grass induced trivial flights that resulted in greater numbers of males entering traps resting on short grass. Most females were caught over bare soil. To minimize the variation in catch between traps used for monitoring cabbage root fly populations, the background beneath each trap should be similar. For maximum capture, the background should be of grass for male flies and of bare soil for female flies. Care is required if data from traps within mulched crops are used to make pest control decisions, as they will underestimate considerably the numbers of flies in such crops.

Dispersive flight by Triatoma sordida

One hundred and thirty-two male and female Triatoma sordida were marked with fluorescent paint and released at an experimental site on the salt flats of central Argentina, distant from any inhabited dwellings. Flight by these bugs commenced just after sunset, and the bugs were then systematically searched for using portable ultraviolet lights. There was no apparent tendency for the bugs to fly in any particular direction, but those whose flight could be observed directly all seemed to fly in approximately straight lines at a height of 0·5–1 m. Of the 86 bugs that flew from the release point, 16 made trivial flights of less than 5 m, 4 landed at distances of 60–90 m away, while the other bugs were not recovered and appear to have flown further than 100 m. As expected from similar studies with T. infestans, the proportion of bugs initiating flight declined with increasing weight-length ratio, but T. sordida showed a much higher propensity for flight under these conditions than did T. infestans.

INFLUENCE OF TEMPERATURE AND LARVAL DENSITY ON FLIGHT PERFORMANCE OF DIABROTICA VIRGIFERA VIRGIFERA LECONTE (COLEOPTERA: CHRYSOMELIDAE)

AbstractThe influence of temperature and larval density on the flight performance of Diabrotica virgifera virgifera LeConte was quantified in the laboratory using a tethered flight system. Temperature had a significant influence on trivial flight performance in males and in both young (5 day) and older (25 day) females. The proportion of beetles undertaking trivial flight, and trivial flight duration and frequency peaked at temperatures around 20–25°C. Generally, males were more active than females at lower temperatures. Female beetles did not display sustained flight behavior at 15 or 35°C and males did not undertake sustained flight at 30 or 35°C. Sustained flight duration was unaffected by temperature. Rearing larvae at different densities influenced adult size but had only subtle effects on adult flight performance. Larval density significantly influenced trivial flight duration and frequency of older females and flight frequency of males but had no effect on young females. In general, trivial flight performance peaked when larvae were reared at moderate densities (500–750 per primary rearing container). In young females the propensity for sustained flight, but not flight duration, declined with increasing larval density.

Influence of Two Mass-Marking Techniques on Survival and Flight Behavior of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae)

Two mass-marking techniques were evaluated in the laboratory to determine effects on survival and flight behavior of Diabrotica virgifera virgifera LeConte. The marking agents were an externally applied fluorescent powder (Day-Clo) and an internal oil soluble dye (Calico oil red) incorporated into an artificial adult diet. Neither technique had a significant influence on survival of 5-10-d-old or 20-25-d-old female or male beetles up to 10 d after marking. Based on tethered-flight assays, marking with fluorescent dust generally had no effect on trivial or sustained flight performance of 5-10-d-old and 20-2S-d-old females or 15-d-old males. Beetles marked with the oil-soluble dye experienced reductions in trivial flight performance, including reductions in individual flight duration, frequency of flight, and total flight time in a 23-h period, for up to 2 d after marking. Both techniques are efficient, but in comparison with Day-Glo fluorescent powder, beetles marked with Calico oil red retain the mark for a shorter time period. Also, beetles marked with Calico oil red should be provided suitable food for at least 2 d after marking to allow recovery of normal fight behavior before they are used in studies involving flight activity.

A COMPARISON OF TRAPPING TECHNIQUES FOR MYTHIMNA CONVECTA (WALKER) (LEPIDOPTERA: NOCTUIDAE)

AbstractThree trap types and 3 food lures were tested for their effectiveness in monitoring field populations of the common armyworm moth, Mythimna convecta (Walker). The traps comprised 1 UV light trap and 2 types of fermentation traps, namely a simple lure pail (‘lure pot'), into which the moths fell and drowned, and a cone trap built over a covered lure pot, the ‘FE trap'. The food lures comprised diluted port wine and sugar, red wine and sugar, and a synthetic lure. There was no significant difference in the attractiveness of wine and port lures, while the synthetic lure did not catch any moths. A vehicle‐mounted net provided an independent measure of airborne density and species composition of the noctuid population at 1 study site. The light trap did not catch many M. convecta. The 2 types of fermentation trap caught similar numbers of M. convecta, although the FE trap had several advantages over the lure pot: the dry moth catches were easier to recover; there was greater selectivity for M. convecta over other abundant noctuids, particularly Agrotis infusa (Boisduval); and the variation in nightly catches more accurately reflected those of the field populations of M. convecta, particularly those engaged in surface or trivial flight.

Morphometric Identification of Wing Polymorphism in Bemisia tabaci (Homoptera: Aleyrodidae)

Principal component analysis revealed sexual dimorphism in wing forms of the sweetpotato whitefly, Bemisia tabaci (Gennadius); fore- and hindwings of females were larger than those of males. Discriminant function analysis indicated subtle morphological differences within the same sex between the wings of migrators and the wings of those engaging only in trivial flight. These differences suggest that B. tabaci employs dispersal strategies used by other dimorphic Homoptera that occupy heterogeneous habitats. Identification of migrating and trivial flying morphs among B. tabaci will be useful in developing a better understanding of the migrational patterns of these insects.

Physiological and structural aspects of adipokinetic hormone function in locusts

AbstractDuring trivial flight in locusts, carbohydrates are the main energy source for the flight muscles, but during long‐term (migratory) flight, lipids mobilised from the fat body are utilised. The supply of fuels to the flight muscles, and the balance between fuels, is determined by peptidic adipokinetic hormones, AKH‐I and AKH‐II, released from the corpora cardiaca. These peptides also indirectly effect changes in lipid‐transporting mechanisms in the haemolymph, and regulate a lipoprotein lipase necessary for lipid uptake by the flight muscles. The sequences of the AKHs of locusts are known and they are members of a family of invertebrate neuropeptides. Extensive structure/activity studies for the action of AKHs on lipid mobilisation have been carried out and, together with studies on secondary structure, the structural features necessary for biological activity are being elucidated. Such information will be of great importance in receptor studies for these hormones, and in the development of powerful agonists and antagonists.

Flight periodicity and infestation size of Sitona lineatus

SUMMARY Sitona lineatus displays two distinct flight periods; a post‐teneral flight in the late summer and a post‐diapausal flight in the spring. The late summer flight begins as soon as adults start to emerge from pupal cells during late July and continues until mid‐October. Maximum aerial density is observed in late August. Less than 10% of newly emerged adults leave the crop by flight, the rest remain in the soil or move to overwintering sites by walking. Spring flight begins in late March if temperatures are above the 12.5°C flight threshold and reaches a peak in mid‐April.Most migratory flight is downwind. Little trivial flight occurs and once individuals have located a crop, redistribution is by walking. Laboratory studies indicate that adults fly most often during the day, particularly at noon.The size of infestations appeared to be independent of the area of legumes grown in a locality with large differences occurring even between neighbouring fields.Examination of the yields of field experiments at Rothamsted demonstrate an unexpected trend for higher yields in later sown spring bean crops. This may be because late sowing avoids infestation by spring migrants.

Regulation of Migratory Flight by Juvenile Hormone Mimic and Inhibitor in the Western Corn Rootworm (Coleoptera: Chrysomelidae)

Adult mated and virgin females were dosed with a juvenile hormone (JH) agonist or antagonist to alter their intrinsic levels of juvenoid compounds. Of 468 females tested, 252 flew, and migratory flight behavior was observed in 145 (31%). No migratory flights were undertaken by untreated virgins. Females treated with juvenile hormone mimic (JHM) and inhibitor (AJH) flew both trivial and sustained flights that were significantly longer in duration and distance than those of controls, but age displacement of peak flight activity varied according to treatment and mating status. There seems to be a definitive window of migratory flight activity in the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, that can be temporally displaced by JHM and AJH treatment. Ovarian development was negatively correlated with migratory flight activity, which substantiates the inverse relationship between flight and reproduction. JH moderates the considerable flight capabilities of the WCR, permitting adaptation of this species to a dynamic, agricultural ecosystem.

Study of Migratory Flight in the Western Corn Rootworm (Coleoptera: Chrysomelidae)

Research on flight activity of the western corn rootworm, Diabrotica virgifera virgifera LeConte, is presented. Field-captured, mated females, aged 2–15 days posteclosion, were flown on flight mills linked to a microcomputer data-recording system. Flight duration ranged from 1 to 17 min for trivial flights; sustained flights lasted up to 4 h. Sustained flights were not made after females were 9 days old. Maximum distances of 24 km for one flight and 39.6 km for all flights during a 24-h period were recorded. Average speed of flight was 16 m/min for trivial fliers and 49 m/min for sustained fliers. Periodicity was observed for both types of flight; greatest flight activity occurred from 1800 to 2400 hours.

Interpretation of the flight activity of Nilaparvata lugens (Stål) and Sogatella furcifera (Horváth) (Hemiptera: Delphacidae) based on comparative trap catches and field marking with rubidium

AbstractDetailed studies were conducted over a five-year period at a rice farm in the Philippines on the flight activity of Nilaparvata lugens Stål) and Sogatella furcifera (Horváth). Suction traps were used to measure aerial density, and catches included immigrants, emigrants and insects undertaking trivial flight. Activity was partitioned using a variety of other trap types. Emigration was effectively monitored using net canopy traps and immigration was best measured using green water traps. Yellow water traps also measured immigration, but when macropterous adults were being produced within the plot, insects undertaking trivial flight were also caught. The light-trap caught immigrant and over-flying migrant insects.

The relationship between pre-flight reproduction and migratory urge in alatae ofAphis fabaeScopoli (Hemiptera: Aphididae)

AbstractAlatae ofAphis fabaeScop. which reproduced before their first flight (flyers) were compared in the laboratory with those which did not (migrants) in order to test whether this difference in behaviour could be taken as an expression of migratory urge. No difference in live weight or dry weight could be found between the two groups. Flyers, however had a higher wingloading than migrants after the final moult but not after pre-flight reproduction. Flyers also had a lower fat/dry weight ratio than migrants and appeared to have more embryos, including a greater number in an advanced state of development. The significance of these observations is discussed in relation to two hypotheses which could account for the different behaviour of migrants and flyers. The results support the hypothesis that migrants have an innately greater urge to take off than flyers, mediated by their crowding experience during development, and that this is likely to result in migratory as opposed to trivial flight.

Migratory and Local Flights in Mole Crickets, Scapteriscus spp. (Gryllotalpidae)1

To study between-habitat and within-habitat flights of Scapteriscus acletus Rehn and Hebard and S. vicinus Scudder at Gainesville, Fla., we trapped those landing at synthesized conspecific calls at paired stations—one in an infested field and the other in a nearby wood (where mole crickets do not breed). Since mole crickets end their flights (long or short) at conspecific calls, the proportion of flying mole crickets that were migrating could be estimated as follows: number ending (migratory) flights in the wood divided by number ending (migratory and trivial) flights in the field. Since this ratio may be biased by unknown details of flight or phonotactic behavior, it should be treated as an index of migration rather than an accurate estimator. During 3 years at one pair of stations, the index for S. acletus ranged between 0.12 and 0.18, and for S. vicinus, between 0.39 and 0.46. During 1 year at two other pairs of stations, the index for S. acletus was 0.09 and 0.14, and for S. vicinus, 0.64 and 1.24. Males of S. vicinus were migratory in a significantly higher proportion of their flights than females. Paired trapping stations can be used to study trivial and migratory flights in other insects if traps catch individuals engaged in both types of flight.

Field Observations on the Seasonal Occurrence of Lygaeus eguestris (L.) (Het., Lygaeidae) with Special Reference to Food Plant Phenology

AbstractLygaeus equestris breeds in open areas. It overwinters in the adult stage, and in the autumn and spring it undertakes migratory flights to and from its hibernation sites. It feeds on the generative parts of a variety of plants. During I969 the population trends of L. equestris and of the flower and seed production of its food plants were studied in eight habitats. High numbers of L. equestris always coincided with peaks in flowering or seed production of the food plants. The spring migration was simultaneous with the start of flowering of the earliest food plants. The autumn migration, however, started when food resources still seemed ample. During the summer, nonmigratory (trivial) flights were important for the bug to keep pace with the changes in food availability. In I970 the distribution of food resources was quite different to that in I969, and consequently the invasion of habitats followed a different pattern. Four periods of flight were recognized: (I) postteneral trivial flights, (2) autumn migration, (3) spring migration, and (4) trivial flights of overwintered bugs. Possible causes of the different types of flight are outlined. The dispersal capacities of the bug are regarded as adaptations to the temporariness of its habitats. The implications of the flight movements on the population dynamics of L. equestris are briefly discussed.