Spring Flight Research Articles

Relationship Between Pheromone-trap Catches and Sunset Temperatures During the Spring Flight to Codling Moth (Lepidoptera: Olethreutidae) Infestations in Walnuts

Relationship between codling moth, Cydia pomonella (L.), pheromone trap catch, sunset temperature, walnut development, and number of subsequently infested walnuts was investigated in several California walnut orchards during 1982 through 1984. A significant relationship between trap catches and numbers of infested nuts was observed during individual years, but no significant relationship between any of the factors was detected when orchard data from different years were analyzed together.

Density‐dependent mating tactics in the Grey hairstreak, Strymon melinus (Lepidoptera: Lycaenidae)

Male Grey hairstreak butterflies employed two different tactics, centred on palo verde trees growing on hilltops in central Arizona. During much of the spring flight season of about four months single males repelled all others from a perch tree. Interactions between the territorial resident in a tree and visiting intruder males were frequent but usually brief. One male retained possession of his perch for two weeks, although changes in ownership were generally much more frequent. But territorial behaviour was abandoned during periods when the number of intruders increased sharply, at which time perched males switched to non‐aggressive patrolling about the preferred palo verdes. Females occasionally visited the palo verdes and interacted with males but no matings were observed. The mating system of the Grey hairstreak, like that of other similar landmark‐defending insects, appears to have evolved in response to a diffusely distributed population of receptive females.

AN IMPROVED REARING PROCEDURE FOR THE CARROT RUST FLY (DIPTERA: PSILIDAE) WITH OBSERVATIONS ON LIFE HISTORY AND CONDITIONS CONTROLLING DIAPAUSE INDUCTION AND TERMINATION

AbstractCarrot rust fly (CRF), Psila rosae (Fabricius) (Diptera: Psilidae), caged with 2-month-old carrot plants at 20 °C, 50–70% RH, and 16:8 L:D laid an average of 109 eggs per female. With ca. 50% survival from egg to pupae, the rearing procedure yielded a 25 × population increase per generation. The duration of the life cycle at 20 °C was ca. 65 days. Calculated threshold temperatures and degree days above those temperatures necessary for complete development were: eggs, 4.5 °C and 94 degree days (°D); larvae, 2.02 °C and 625 °D; and pupae, 1.47 °C and 374 °D. Larvae collected in the field in fall developed normally when incubated at 22 and 19 °C; ca. 40% of the pupae entered diapause at 16 °C, and 100% at 13 and 10 °C. Fall-collected larvae chilled at 1 °C for ca. 3 months developed normally at all temperatures including those which induced diapause in pupae from unchilled larvae. With laboratory-reared pupae, 100% diapause was induced with > 10 days exposure to 13 or 10 °C. Twenty weeks storage at 1 °C was sufficient to terminate diapause in > 95% of the pupae. The ability of both CRF larvae and pupae to survive cold temperature conditions suggests that 2 separate spring emergence peaks may occur, which could have important implications if the spring flight is to be predicted on the basis of °D accumulations.

Monitoring Susceptibility to Azinphosmethyl in Field Populations of the Codling Moth (Lepidoptera: Tortricidae) with Pheromone Traps

A procedure was developed to screen field populations of Cydia pomonella (L.) directly for resistance to azinphosmethyl or other toxicants. Male moths were collected in the field with pheromone traps and assayed with azinphosmethyl by topical application to the dorsal thorax directly on the adhesive-coated trap surface. The first flight had a steeper concentration-mortality regression than the second flight, indicating an increase in variability of the toxicological response over the season. The LC50 of moths trapped during the spring flight was somewhat higher (0.22 µg/moth) than during the summer (0.08–0.16 µg). Assays of laboratory-reared moths from the same location kept in plastic cages or on sticky trap surfaces to simulate the test procedure with field-collected moths yielded LC50’s in the same range (0.10–0.14 µg/moth). The longevity of moths and their toxicological response was not affected by the polybutene adhesive provided it was applied as a thin uniform film to the trap surface. Susceptibility to azinphosmethyl increased considerably with age in both sexes and was not correlated with loss in body weight. Female moths were slightly more susceptible when azinphosmethyl was applied to the thoracic venter instead of the dorsum. Males were equally susceptible to either application.

Early Spring Flights of American White Pelicans: Timing and Functional Role in Attracting Others to the Breeding Colony

Observation de l'activite aerienne de Pelecanus erythrorhynchos appartenant a trois colonies reproductrices differentes du bord du East Shoal Lake, Manitoba (1981-83). Mise en evidence du fait que les vols manifestes servent a attirer d'autres pelicans vers un site colonial actif et peuvent faciliter ainsi la formation d'agregations reproductrices synchrones chez cette espece

Hilltopping in the Nymphalid Butterfly Chlosyne californica (Lepidoptera)

During a 2-month spring flight season, males of the butterfly Chlosyne californica perch in and defend open areas of ca. 5-10 m2 near prominent palo verdes on ridgetops in the Sonoran Desert. Some males return to defend the same territory several days in a row, each day repelling an average of 3-4 intruders over the 1 st 2 hr of the daily flight period. Females fly to ridgetop territories where they are pursued and mated by resident males. Many aspects of the behavior of this species are convergent with other unrelated territorial hilltopping insects. Not all hilltopping butterfly species are territorial and differences in population densities may play a role in the evolution of behavioral diversity within this group.

Convergent Evolution in Perching and Patrolling Site Preferences of Some Hilltopping Insects of the Sonoran Desert

Males of the pompilid wasp, Hemipepsis ustulata, defend palo verde trees on mountain ridges in the Sonoran Desert. The preferences of the wasps for different trees on one ascending ridge remained essentially the same over four spring flight seasons. The wasps preferred large trees high on the ridge. Other insects unrelated to the wasp behaved similarly and focused their territorial or non-territorial mate-searching on or near the same sites most preferred by the wasps. Convergent preferences of hilltopping male insects may reflect the capacity of the compound eye of insects to detect some distant landmarks more easily than others. The prominent ridges that rise from the upland Sonoran Desert of central Arizona attract a diversity of insects, including tarantula hawk wasps, various butterflies, and bot flies. In the spring months males of these hilltopping species patrol or perch in or near conspicuous palo verdes (Cercidium microphyllum) growing on the backbone of the ridges. There they await the arrival of receptive females. Males of some species defend their patrolling or perching locations; in other species males exhibit little or no aggression toward conspecifics. But whether territorial or not, hilltopping males are not distributed evenly along ascending mountain ridges. Previous studies (Alcock, 1981, 1983a,b; Alcock and Schaefer, 1983) of three territorial members of the hilltopping complex (a pompilid wasp, Hemipepsis ustulata; a hairstreak butterfly, Atlides halesus; and a rodent bot fly, Cuterebra sp.) have documented that: (1) certain locations are much more likely to be occupied than others by territorial males, (2) territorial preferences appear to be stable from year to year, and (3) different species have similar preferences for available territory sites. The purpose of this report is (1) to provide new data on the year to year stability of territorial preferences of the wasp Hemipepsis ustulata, (2) to identify the key parameters of perch sites that determine their relative attractiveness to the wasps, and (3) to present new evidence showing that other species, both territorial and non-territorial, rank available mate- locating sites along a ridge in much the same order as the wasp.

Concepts for Combining Suppression of European Corn Borer (Lepidoptera: Pyralidae) Adults and Larvae in Center-Pivot-Irrigated Corn

Single aerial applications of insecticide were applied to noncrop vegetation in perimeters of fields in order to control spring or summer flights of Ostrinia nubilalis (Hubner) moths during 1981 and 1982. When compared to larval populations in untreated fields, significant (P <0.10) treatment differences were observed during 1981 summer moth flights, but reductions (33%) did not appear comparable with conventional larval control procedures. Single aerial applications of insecticide were applied to both crop and noncrop vegetation during 1981 and 1982 summer moth flights. Significant (P < 0.10) treatment differences were observed in both years and reductions, 67 and 82% respectively, appeared comparable with conventional larval control. However, results were probably confounded with larval control. Interpretation of the data suggests that conventional larval control could be enhanced by incorporating the following: use of insecticides efficacious against both adults and larvae; treatment of both crop and noncrop vegetation; and timing of insecticide applications to suppress breeding populations.

Predicting Spring Flight of Nantucket Pine Tip Moth (Lepidoptera: Olethreutidae) by Heat Unit Accumulation1

A procedure was developed to predict spring flight of Rhyacionia frustrrana (Comstock) by using temperature records and number of males captured in traps baited with virgin females during 1974 to 1980. The procedure is based on heat units accumulated above a threshold temperature of O°C beginning on 1 January. Flight began at ca. 389 heat units and was completed at 808 heat units. Prediction was within 2 days for 20% flight. The procedure was confirmed by data collected in 1981. These results provide information with potential for timing spray applications to control R. frustrana.

The inhibitory pheromone of queen fire ants: effects of disinhibition on dealation and oviposition by virgin queens

1. Virgin queen fire ants,Solenopsis invicta Buren, that overwintered in parental nests participated in mating flights in early spring, and some were shown to have been laying eggs in queenright colonies before leaving. Virgin queens reared in spring had immature oocytes in their ovarioles when they left on mating flights. 2. When released from pheromonal queen influence by isolation, 98% of both overwintered and spring-reared virgin queens oviposited and exhibited colony founding behavior, but only 73% dealated. The alary muscles of all of them histolyzed, however, whether or not they dealated. The eggs laid by both the overwintered and springreared virgin queens were larger than those laid by physogastric mated queens, and less than 1% were viable. 3. When spring-reared virgin queens were disinhibited by dividing colonies into queenright and queenless halves, some virgin queens in the queenless halves dealated and oviposited. A frequency distribution of the sizes of eggs laid by these virgin replacement queens was bimodal. The larger eggs were similar in size to those laid by spring-reared virgin queens in isolation and less than 1% were embryonated. They served a trophic function. The smaller eggs were not as small as those laid by mated queens, but the majority were embryonated. The number of eggs laid by virgin replacement queens in 5 h was positively correlated with the maximum number of oocytes/ovariole. The size of eggs laid by virgin and mated queens was a function of the oviposition rate. 4. The results demonstrate that the inhibitory pheromone of queen fire ants acts directly on virgin queens and that it prevents muscle histolysis and rapid oogenesis. The former hypothesis that the pheromone acts mainly on workers and prevents them from causing virgin queens to dealate is, therefore, disproved. 5. A new working hypothesis consistent with the experimental results and with previously published information is that a single queen pheromone regulates the secretion, and titer, of juvenile hormone.

Collections of Prospaltella perniciosi Tower (Hymenoptera: Aphelinidae) on San Jose Scale (Homoptera: Diaspididae) Pheromone Traps

The aphelinid endoparasite Prospaltella perniciosi Tower was collected on sticky traps baited with synthetic pheromones and virgin females of the San Jose scale, Quadraspidiotus perniciosus (Comstock). Right of overwintered parasites in central California correspond closely with spring flights of male scale and maturity of female scale. Subsequent flights of Prospaltella are not as closely synchronized with mature scale populations, and show a general decline through the remainder of each season. If the parasites are using the sex pheromones produced by mature female scales in host-finding behavior, this asynchrony of summer populations could help explain the decline of parasite populations.

Evaluation of Sex Attractant and Blacklight Traps for Monitoring Black Cutworm and Variegated Cutworm12

Sex attractant-baited sticky traps were evaluated against blacklight (BL) traps for monitoring adults of black cutworm, Agrotis ipsilon (Hufnagel), and variegated cutworm, Peridroma saucia (Hübner), populations in New York and New Jersey. Sex attractant trap catches during spring flights significantly exceeded BL trap catches. Summer ant fall flight catches were greater in BL traps than in sex attractant-baited traps.

FACTORS AFFECTING THE TEMPORAL DISTRIBUTION OF THE SPRING FLIGHT OF THE EUROPEAN CORN BORER, OSTRINIA NUBILALIS (LEPIDOPTERA: PYRALIDAE)

AbstractA multiple regression analysis was used to establish which weather factors and population parameters were important in determining the emergence pattern of the spring flight of the European corn borer, Ostrinia nubilalis (Hbn.), as measured by light trap catches. Equations which estimated the slope and intercept of a line representing the probit of cumulative percentage emergence vs. degree days had as independent variables the intercept of the previous year’s regression line and the average temperature for the preceding September, December, February, and April. A comparison of methods used to estimate the emergence pattern showed that the average deviation of the average date method was 5.0 days, the average slope and intercept method 2.8 days, and multiple regression method 1.6 days.

Alate aphid (Homoptera: Aphididae) species and their relative importance as field vectors of soybean mosaic virus

SUMMARYA technique was developed and deployed in central Illinois to trap and assay aphid alatae for incidence of soybean mosaic virus (SMV) transmission among naturally occurring transient aphid populations downwind of a field of infected soybean. In a 2‐yr study, 1709 alate aphids were trapped alive and assayed, 4.2% of which transmitted SMV. Five species of aphids accounted for more than 93% of the transmissions: Aphis craccivora Koch, Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), Rhopalosiphum maidis (Fitch), and Rhopalosiphum padi (L.). At least 55 additional species were assayed, five of which transmitted only once. Others did not transmit. Because virus infection during the early growth stages of soybean increases the loss of yield and the percentage of seed‐borne virus, vector species that tend to fly middle to late spring are, from an economic point of view, more important in the spread of SMV. R. maidis flew in mid‐ to late summer and in autumn. R. padi was not abundant at any time of year and its transmission efficiency was low. M. persicae tended to fly in mid summer. Two species (A. craccivora and M. euphorbiae) which had major flights in late spring and early summer and relatively high transmission efficiencies are potentially important in the economic spread of SMV in central Illinois. A third species, Aphis citricola Van der Goot, may also be important because it flies in late spring and laboratory data suggest it is a relatively efficient vector of SMV. A. citricola was not assayed by our technique because we trapped in the morning and this species appears to fly later in the day.

Temperature Thresholds for Spring Emergence and Flight of the Boll Weevil 12

A strong relationship was found between temperature and emergence of boll weevils from overwintering sites. The threshold temperature above which overwintering weevils accumulated heat units was 10.85°±1.3°C. Early fall cohorts required a higher number of accumulated heat units than did late fall cohorts. First-emerging weevils of early cohorts had a lower tendency to subsequently initiate flight activity than did first-emerging weevils of later cohorts. The temperature threshold for flight of 95–98% of newly emerging weevils was 20°C.

Codling Moth: Control on Pears with Diflubenzuron and Effects on Nontarget Pest and Beneficial Species13

Diflubenzuron was evaluated in southern Oregon pear orchards for control of the codling moth, Laspeyresia pomonella (L.), and for effects on nontarget species. Diflubenzuron was most effective when the 1st summer treatment was timed to coincide with 1st moth flight in the late spring. Increased rates of diflubenzuron improved codling moth control but were more disruptive than lower rates to natural enemies of the pear psylla, Psylla pyricola Foerster. Diflubenzuron used at 0.14 kg AI/ha caused no reduction in psylla natural enemies compared to densities in untreated checks. Pear psylla levels were 3- to 4-fold higher in standard treatments with azinphosmethyl or phosmet compared to those in diflubenzuron plots. This was attributed to the reduction in natural enemies found in the organophosphate control program. No increase in two spotted spider mite, Tetranychus urticae Koch, densities was noted following diflubenzuron treatments compared to the untreated check plot.

FORECASTING CODLING MOTH PHENOLOGY BASED ON PHEROMONE TRAP CATCHES AND PHYSIOLOGICAL-TIME MODELS

AbstractThe relationship of pheromone trap catch to emergence and oviposition of the codling moth was defined for the two-generation climate of Michigan. Catch anticipated emergence and oviposition during spring flight when the trap displayed greatest efficiency, but lagged behind emergence and closely followed oviposition during the second generation. Trapping efficiency declined towards the end of the first generation and was generally lower during summer flight. Factors which possibly relate to this efficiency loss are discussed. First catch and the catch peaks in both generations were evaluated as reference points for the prediction of phenological events (particularly egg hatch) in both generations Of four forecasting methods, degree day and developmental unit summations, starting from first catch, for the preoviposition and incubation period were most reliable in predicting the beginning of spring brood egg hatch.

Pecan Bud Moth: 1 Captures in Georgia in Traps Baited with the Pheromone of the Oriental Fruit Moth 13

Male pecan bud moths, Gretchena bolliana (Slingerland), were captured during the spring flights (April–May) in traps placed in the canopy of pecan trees and baited with 2 μ1 of ( Z )-8-dodecenyl acetate, a synthetic sex pheromone of the oriental fruit moth, Grapholitha molesta (Busck), containing 7% E isomer and 2 μ1 of dodecyl alcohol (a synergist). Pheromone traps placed 9.1 m above ground caught more male pecan bud moths than those at lesser heights. During the summer and fall flights (June –Oct.), appreciable numbers of male pecan bud moths were caught in unbaited blacklight traps.

Mole Crickets: Ecology, Behavior, and Dispersal Flight (Orthoptera: Gryllotalpidae: Scapteriscus ) 23

The southern mole cricket, Scapteriscus acletus Rehn and Hebard, and the changa, S. vicinus Scudder, are pests of turf and agricultural crops in the southeastern United States. Both species fly during spring and fall in Gainesville, Fla. The numbers of flying acletus and vicinus were monitored each night during those seasons (1972–73). Monitoring was done by (1) attracting the flying adults of these 2 species to loudspeakers broadcasting tape recordings of natural and synthetic mole cricket calling songs and (2) collecting flying adults to UV and fluorescent lights. About 28 times more mole crickets were collected during the spring flight than during the fall flight. Spring collections were 55% acletus ( n = 5675) and fall collections were 16% acletus ( n = 199). During 1972 and 1973, females comprised 83% of those collected of both acletus ( n = 9161) and vicinus ( n = 7521). The percent of females that had mated increased as flight season progressed. The flight started soon after sunset and continued for an hour. Of 1844 adult acletus marked and released 35 were recaptured on subsequent nights, proving that at least 2% of adults fly more than once. Three adults were recaptured twice. Recaptures were made up to 6.5 wk and at distances as great as 0.7 km. S. acletus flight speed was estimated at 7–11 km/h. Flights of acletus and vicinus did not occur below 18°C (air and soil) temperature.

Biology of Stenolophus (=Agonoderus) comma, a Ground Beetle of Cropland1,2

Stenolophus comma (F.), a common carabid in cropland in South Dakota, is transamerican in distribution and is found in a wide variety of habitats. Adults are active in the field from early April to early November. Dispersal flights occur from mid-April to mid-October; spring flights are often heavy during the daytime, and summer flights are heavy during the night. Eggs are laid in cells in the soil, and the adults and larvae may be found tunneling through the soil. There are 3 larval instars; the mean period from egg to adult takes about 47 days. The new-generation adults that appear from mid-June to mid-October are known to overwinter, oviposit from late April to late July, and continue this overwintering and oviposition cycle through 3 years.