Peak Adult Emergence Research Articles

The Effect of Different Thiamethoxam Concentrations on Riptortus pedestris Development and Fecundity.

The stink bug, Riptortus pedestris (Fabricius) (Hemiptera: Alydidae), is a highly destructive pest that significantly damages legume crops in East and South Asia. Neonicotinoid insecticides containing thiamethoxam are widely used to control R. pedestris in soybean fields. However, the current knowledge on the impact of different thiamethoxam concentrations on R. pedestris growth and reproduction is lacking and insufficient. The present study investigated the effects of thiamethoxam on the biological traits of R. pedestris after treatment with LC10 (19.8 mg/L), LC20 (31.6 mg/L), LC30 (44.2 mg/L), LC40 (58.9 mg/L), and LC50 (77.0 mg/L) concentrations. These five thiamethoxam concentrations (LC10~LC50) reduced adult longevity and fecundity in the F1 generation females. Thiamethoxam treatment also significantly decreased the population trend index, intrinsic rate of increase, net reproductive rate, gross reproductive rate, and finite rate of increase and increased the mean generation time. These results show that thiamethoxam hinders and suppresses the development and growth of the F1 population of R. pedestris. Thiamethoxam is recommended for spray control during peak adult emergence, as it not only has a controlling effect on the parental generation but also a negative impact on the F1 generations.

Maggots cannot live on meat meal alone: production parameters for mass rearing of the ovoviviparous blowfly, Calliphora dubia (Diptera: Calliphoridae).

This study determined a cost-effective larval diet for rearing Calliphora dubia Macquart for use as a potential managed pollinator in Australia. This fly has potential as a pollination species to support honey bees (Apis mellifera). Larvae of C. dubia were reared mostly in meat meals with varying amounts of either whole egg powder, whole eggs (+ shell), bran flakes, skimmed milk powder, brewer's yeast, or poultry oil. This was done from an economic and production perspective to support commercial rearing. Several laboratory-based studies determined the growth and output from various ingredient combinations. Larvae fed 90% meat meal and 10% whole egg powder developed rapidly through to pupation with a high pupation rate, adult size, and percent adult emergence. Given the high cost and difficulty in sourcing whole egg powder, media comprising mostly meat meals with the addition of bran flakes and whole eggs also supported rapid larval development, pupation rate, and adult emergence. The ideal amount of media/larvae was 0.5 g/larvae to support high pupation rates and adult emergence. Adult eclosion occurred over 4-5 days, even when larvae were laid and fed within 1 h on ample media. Commercial mass rearing would then require daily cohorts of larvae to ensure peak adult fly emergence over 1-2 days for release into a crop. Mass-rearing C. dubia should use meat meal as the base ingredient with bran flakes and whole eggs added and fed at 0.5 g of media/larvae. Based on the current media ingredient costs, rearing 1-m adult C. dubia would cost just over $500 (US$342).

Adult Emergence and Morphometrics of Chinese Citrus Fly, Bactrocera minax (Enderlein) (Diptera: Tephritidae) in Nepal

Chinese citrus fly, Bactrocera minax is a destructive and univoltine pest of citrus fruits. Geographical altitudinal gradients as well as prevailing climate affect the biology and ecology of insect. Hence, this study aimed to ascertain the effect of altitude on the adult emergence and morphological variations in various ecological settings of Ramechhap district of Nepal from February to June 2021 in citrus orchard. Six altitude ranges were selected in 50 m distance from 1200 to 1500 m above sea level (masl), ranging from 1201-1250 masl, 1251-1300 masl, 1301-1350 masl, 1351-1400 masl, 1401-1450 masl and 1451-1500 masl. The peak adult emergence periods were the 2nd, 3rd, 4th week of April in 1201-1250 masl, 1251-1300 masl, 1301-1350 masl, respectively, followed by 1st, 2nd and 3rd week of May in 1351-1400 masl, 1401-1450 masl, 1451-1500 masl, respectively. Morphometrics of Chinese citrus fly such as weight, length and width of pupa and adult were almost similar to the species collected in various altitudes. The average body length of male Chinese citrus fly adult was 11.58± 0.112 mm while female was 15.57± 0.076 mm. The average wingspan of male was 20.71± 0.285 mm while that of female was 23.14± 0.156 mm. The longevity of adult Chinese citrus fly species increased with increase in altitude. This information could be useful to design an appropriate management plan of Chinese citrus fly in various altitudinal gradients of Nepal.

Emergence of Walnut Husk Maggot Adults in Central Illinois and Potential for Control with Metarhizium brunneum.

The walnut husk maggot, Rhagoletis sauvis (Loew) (Diptera: Tephritidae), causes damage to walnuts when maggots feed inside the husk. September applications of the entomopathogenic fungi Metarhizium brunneum F52 as microsclerotia laced granules to the soil in Illinois were evaluated for pest control based on adult emergence during the following summer. Over 3 yr in central Illinois, adult emergence began near 1 July, peaked before 23 July, and emergence extended as late as 23 August. One summer application of fungus (30 June) when pupae were present, did not reduce fly emergence. Of two September applications that targeted maggots as they move to the soil to pupate, one significantly reduced the number of flies emerging from treated plots when compared with untreated plots for one 7-d sample collected 29 July 2020. Emergence trap data show a defined peak adult emergence in July for central Illinois while September applications of granules containing Metarhizium brunneum (Petch) (Hypocreales: Clavicipitaceae) show shows potential to reduced subsequent fly emergence.

Degree-day models to predict carrot weevil (Coleoptera: Curculionidae) emergence and oviposition in Nova Scotia, Canada

AbstractCarrot weevil, Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae), is a pest of carrot (Daucus carota var. sativus Hoffmann; Apiaceae) throughout eastern Canada. Carrot weevil emergence and oviposition were monitored in commercial carrot fields in Nova Scotia. Cumulative degree days were calculated using a base temperature of 7 °C (DD7), and models were developed to predict cumulative emergence and oviposition using nonlinear regression. Cumulative emergence and oviposition were adequately explained as functions of DD7 by a three-parameter sigmoidal Hill equation. Our emergence model predicted initial and peak adult emergence at 35 and 387 DD7, respectively, with oviposition on carrot baits occurring as early as 42 DD7. Models were then validated to evaluate how well they performed. Oviposition on carrot plants began at the fourth true-leaf stage (342 DD7) and continued until eleventh true-leaf stage. Growers using these models can identify their window of opportunity to manage their carrot weevil populations targeting the majority of emerged adults before oviposition begins in the field.

A new substitute host and its effects on some biological properties of Ooencyrtus kuvanae.

Lymantia dispar (L.) (Lepidoptera: Lymantriidae), commonly known as the gypsy moth, is a serious forest pest, and beneficial insects are particularly important for reducing its population numbers. Ooencyrtus kuvanae (Howard) (Hymenoptera: Encyrtidae) is an arrhenotokous, solitary egg parasitoid of L. dispar. In this study, we evaluated a new substitute host, Philosamia ricini (Danovan) (Lepidoptera: Saturniidae) for O. kuvanae. We investigated some of the biological effects of O. kuvanae on P. ricini eggs. In this context, the importance of the age of the female parasitoid (1, 3 or 5 days old), host age (1-2 and 3-4 days old) and host number (40, 60 and 80 host eggs) were examined under laboratory conditions (25 ± 1 °C, 65 ± 5% relative humidity and a 16 : 8 h photoperiod [light : dark]). The highest rate of offspring production (89.90%) occurred with 40 (1-2-day-old) host eggs and 5-day-old females. The mean developmental period ranged from 16.5 ± 0.08 days to 18.7 ± 0.08 days. The mean lifespan of the parasitoid was 51.10 ± 1.1 (n = 60) days with bio-honey and 3.92 ± 0.14 (n = 60) days without food. The mean fecundity was 68.88 ± 3.22 offspring/female. Peak adult emergence occurred between 2 and 9 days. The mean oviposition and mean post-oviposition periods of the female parasitoid were 22.76 ± 1.37 days and 13.64 ± 1.40 days, respectively. O. kuvanae was reared for more than ten generations on the eggs of P. ricini. Based on our findings, P. ricini can be used to rear O. kuvanae for the biological control of L. dispar.

Thermoperiodism Synchronizes Emergence in the Alfalfa Leafcutting Bee (Hymenoptera: Megachilidae).

Alfalfa seed production in the northwestern United States and western Canada is heavily dependent upon the pollinating services of Megachile rotundata (F.) (Hymenoptera: Megachilidae). M. rotundata females nest in cavities either naturally occurring or in artificial nesting blocks. Because of the physical nature of the nest, M. rotundata brood may have limited to no exposure to photoperiodic cues in order to regulate important circadian functions. Therefore, various thermoperiod regimes were used to characterize the possible role of thermoperiodism in synchronizing M. rotundata adult emergence. Adult emergence was monitored using a microprocessor-controlled event logger. Incubating bees under constant 29°C and darkness resulted in an arhythmic adult emergence pattern. Exposing developing M. rotundata to a thermoperiod synchronized emergence to the beginning of the thermophase and decreased the total number of days required for all adults to emerge. The amplitude of the thermoperiod regulated the timing of peak emergence in relationship to the increase in temperature. A thermoperiod amplitude of only 2°C was sufficient to synchronize peak adult emergence to take place during the rise in temperature. Increasing the amplitude of the thermoperiod to 4 or 8°C caused a positively correlated shift in peak emergence to later in the thermophase. Brood stored under constant 29°C and darkness for different durations (May or June early in the growing season or July or August late in the growing season) or under a fluctuating thermal regime (base temperature of 6°C and daily 1-h pulse of 20°C until September or November) maintained their capacity for entraining emergence timing by thermoperiodism.

Seasonal Activity, Within-Tree Distribution, and Ovipositional and Feeding Preference of the Elm Leafminer, Fenusa ulmi (Hymenoptera: Tenthredinidae)

Seventy-six different elm taxa were visually rated for elm leafminer (Fenusa ulmi Sundevall) defoliation. European elm taxa were more found to be more susceptible to feeding damage by the elm leafminer compared to Asian and North American elm taxa. European elms U. glabra, U. elliptica, U. sukaczezii, and elms with U. glabra-wallichiana parentage were highly susceptible to elm leafminer leaf feeding damage. Of the 37 Asian elm taxa evaluated, only U. laciniata was highly susceptible to feeding damage. The North American species U. rubra was the only North American elm susceptible to elm leafminer feeding. Adult emergence, initial leafmining, and cessation of leafmining were highly correlated with indicator plant full bloom phenology providing an accurate degree-day (DD) model for practitioners in predicting and monitoring for elm leafminer life stage development and related plant damage. Elm leafing out phenology of susceptible European elms was highly correlated with elm leafminer adult emergence and oviposition. Less susceptible European elm taxa, such as U. procera, and U. carpinifolia and cultivars, consistently leaf out later after peak adult leafminer emergence. Interestingly, the majority of Asian elm taxa such as U. davidiana, U. japonica, U. lamellosa, and U. pumila leaf out at the same time as susceptible elm taxa, but experience no or negligible feeding damage. Two Asian species, U. wilsoniana and U. parvifolia, leaf out later after peak adult emergence and oviposition has passed. No consistent pattern was observed for within tree ovipositional wounds and subsequent leafminer feeding damage for tree height or cardinal direction for both small and large elm tree species. Results from this study indicate there is a large number of Asian and North American elm taxa that provide a rich genetic pool for future elm breeding programs.

Using Sex Pheromone Trapping to Explore Threats to Wheat From Hessian Fly (Diptera: Cecidomyiidae) in the Upper Great Plains

Before embarking on the 5-10 yr effort it can take to transfer plant resistance (R) genes to adapted crop cultivars, a question must be asked: is the pest a sufficient threat to warrant this effort? We used the recently discovered female-produced sex pheromone of the Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae),to explore this question for populations in the Upper Great Plains. Methods for pheromone trapping were established and trapping data were used to explore geographic distribution, phenology, and density. The pheromone lure remained attractive for up to 10 d and only attracted male Hessian flies. Traps placed within the crop canopy caught flies but traps placed above the crop canopy did not. Hessian flies were trapped throughout North Dakota starting in the spring and continuing through the summer and autumn. Densities were low in the spring but increased greatly during the early part of the summer, with peak adult emergence taking place at a time (July/August) when spring wheat was being harvested and winter wheat had not yet been planted. In the autumn, adults were found at a time when winter wheat seedlings are growing. The discovery of flies on Conservation Reserve Program land supports the idea that pasture grasses serve as alternate hosts. We conclude that the Hessian fly is a risk to wheat in the Upper Great Plains and predict that global warming and the increasing cultivation of winter wheat will add to this risk.

애반딧불이(Luciola lateralis)의 생태학적 특성

애반딧불이의 유충상륙은 약 5.3일이 소요되었고 고치방을 만든 후 약 6.6일에 번데기로 변태하였다. 고치방의 크기는 길이 10.1 mm, 폭 4.7 mm, 벽두께 1.3 mm이었다. 번데기는 약 10.5일이 소요되었다. 성충이 되고 고치방 속에 약 6.8일 후에 출현하였다. 성충의 출현은 PM. 9시를 전후로 최대였고 PM. 10시에 감소하였다. 성충출현의 최적지온은 <TEX>$23.4^{\circ}C$</TEX>였다. 실내개체군(Lab-type)의 암컷 및 수컷과 야외개체군(Nat-type)의 수컷은 수명이 비슷하였고, Nat-type의 산란 수는 200<TEX>${\sim}$</TEX>400립 구간을 형성하였다. 단지, Nat-type의 암컷은 수명이 짧았으며, 산란 횟수와 산란 수는 적었다. 산란횟수에서 야외개체군은 2회와 실내개체군은 4회로 차이를 보이는 것은 야외개체군은 시료 채집 이전에 산란했을 가능성을 배제할 수 없다. The Luciola lateralis larva took 5.3 days from climbing on the land to the pupal cocoon formation. It took 6.6 days for a larva to eventually transform to a pupa after building a pupal cocoon. The size of pupal cocoon was 10.1 mm in length, 4.7 mm in width and its wall thickness was 1.3 mm. The mean pupal period was 10.5 days. The adult stayed 6.8 days in the pupal cocoon before escaping the cocoon. The peak adult emergence appeared around 9 p.m., and decreased after 10 p.m. The optimal soil temperature for emergence was <TEX>$23.4^{\circ}C$</TEX>. The female adult of the natural population (Nat-type) lived shorter, laid fewer eggs, and the oviposition frequency was fewer than that of the Lab-type individuals. However, a few individuals from the natural population laid 200-400 eggs. The less number of oviposition in the natural population may be due to the fact that the female adults might lay eggs before the collection for the experiment.

Development and Reproduction of the Egg Parasitoid, &lt;I&gt;Gonatocerus ashmeadi&lt;/I&gt; Girault (Hymenoptera: Mymaridae), as a Function of Temperature

The development, fecundity, and life table parameters of Gonatocerus ashmeadi Girault, an egg parasitoid of the glassy-winged sharpshooter, Homalodisca coagulata (Say), were studied in the laboratory at six constant temperatures between 12 and 32°C. At 12°C, the parasitoid failed to develop beyond the third instar, and durations of the egg stage and the first and second instars were prolonged. Development from the egg stage to adult emergence varied from 27.1 d at 16°C to 9.5 d at 28°C. Temperature thresholds for development ranged from 3.8°C for first-instar larvae to 12.8°C for the pupal stage. The thermal constants were lowest for the second-instar larvae (26.7 DD) and highest for the pupae (75.4 DD). Nearly 207 DD were required above the lower temperature threshold of 8.5°C to complete development from egg to adult. The optimum temperature for egg to adult development was 29.2°C. Survival from egg to adult was 67.4% at 16°C and ranged from 83.4 to 86.7% between 20 and 32°C. At 16–32°C, the population had a type I survivorship pattern. At 16°C, longevity of adult females and males averaged 27.1 and 19.0 d, respectively, but declined to 6.4 and 6.9 d at 32°C. At 20–32°C, peak adult emergence occurred on the first day of emergence, but at 16°C, it was greatest on the second day. When exposed to temperatures ranging from 16 to 32°C, the female:male sex ratio was similar, ranging from 3.4 to 5.6. Lifetime fecundity was greatest at 24°C and lowest at 32°C, with the maximum net reproduction also occurring at 24°C. Greatest intrinsic and finite rates of increase, shortest population doubling time, and mean generation time occurred when G. ashmeadi was held at 28°C. The parameters defined in this study can influence geographical distribution and are important for the mass-rearing this wasp as biological control agent for the glassy-winged sharpshooter.

Aromatherapy in the Mediterranean fruit fly (Diptera: Tephritidae): sterile males exposed to ginger root oil in prerelease storage boxes display increased mating competitiveness in field-cage trials.

Previous research showed that exposure to ginger root, Zingiber officinale Roscoe, oil increased the mating success of mass-reared, sterile males of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). This work, however, involved the exposure of small groups of males (n = 25) in small containers (volume 400 ml). Several sterile male release programs use plastic adult rearing containers (so-called PARC boxes; hereafter termed storage boxes; 0.48 by 0.60 by 0.33 m) to hold mature pupae and newly emerged adults before release (approximately = 36,000 flies per box). The objective of the current study was to determine whether the application of ginger root oil to individual storage boxes increases the mating competitiveness of sterile C. capitata males. Irradiated pupae were placed in storage boxes 2 d before adult emergence, and in the initial experiment (adult exposure) ginger root oil was applied 5 d later (i.e., 3 d after peak adult emergence) for 24 h at doses of 0.0625, 0.25, 0.5, 1.0, and 2.0 ml. In a second experiment (pupal-adult exposure), ginger root oil was applied to storage boxes immediately after pupal placement and left for 6 d (i.e., 4 d after peak adult emergence) at doses of 0.25 and 1.0 ml. Using field cages, we conducted mating trials in which ginger root oil-exposed (treated) or nonexposed (control) sterile males competed against wild-like males for copulations with wild-like females. After adult exposure, treated males had significantly higher mating success than control males for all doses of ginger root oil, except 2.0 ml. After pupal-adult exposure, treated males had a significantly higher mating success than control males for the 1.0-ml but not the 0.25-ml dose of ginger root oil. The results suggest that ginger root oil can be used in conjunction with prerelease, storage boxes to increase the effectiveness of sterile insect release programs.

Vacant niche in alpine habitat: the case of an introduced population of the butterfly Erebia epiphron in the Krkonoše Mountains

Abstract A vacant niche in alpine habitats of the Krkonose Mts. (Western Sudetes, Czech Republic) was colonised by a non-native butterfly Erebia epiphron (Lepidoptera: Nymphalidae, Satyrinae) as a result of artificial introduction of 50 females in 1932 and 1933. The species established a large population occupying an entire area above the timberline on one of parallel ridges (East) of the mountains, but it has not yet colonised the parallel Western ridge, which is almost identical in area, altitude and vegetation. We compared altitudinal distribution and adult habitats of the alien species and of its native congener, E. euryale. Distribution of both species was significantly affected by altitude, but habitat type predicted butterfly numbers better than altitude in regression models. The introduced species was sympatric with the native one near the timberline, but its altitudinal optimum was higher, within tundra grasslands, where the native E. euryale did not occur. Peak adult emergence of E. euryale was later than in E. epiphron and followed identical pattern in allopatry. The failure of E. epiphron to colonise the Western ridge is attributable to its incapability to disperse across wooded areas. The Krkonose alpine communities are unsaturated with species, which is striking in comparison with native butterfly fauna of lower Hrubý Jesenik Mts. We interpret this by a past encroachment of alpine grasslands in the Krkonose Mts. by the dwarf pine Pinus mugo.

Laboratory culture of Chironomus tentans for use in toxicity testing: optimum initial egg-stocking densities

The midge Chironomus tentans Fabricius is a commonly used freshwater invertebrate in sediment toxicity tests. Rigorous laboratory culturing techniques are needed to provide organisms of uniform quality and known age for use in testing and for the continuation of the culture itself. This study was conducted to determine the effect of initial culture stocking density on: (1) post-hatch (larval) dry weight, body length and head-capsule width at 10 and 20 days; (2) time to emergence; (3) number and sex of emergent adults; (4) number of larvae and pupae at test termination (day 42 post hatch); and (5) adult dry weight. Three egg stocking densities were used 690 (1.1 eggs cm−2), 1043 (1.7 eggs cm−2) and 1463 (2.4 eggs cm−2). Mean weight of larvae at 10 days in high density tanks (0.13 mg/organism) was significantly higher (P=0.003) than both the medium and low density tanks (0.10 and 0.09 mg/organism, respectively). No significant differences between the three stocking densities were observed for the body length or head-capsule width at either 10 or 20 days post-hatch. Although not statistically significant, larval dry weight decreased with increased stocking density at day 20. A significantly (P=0.02) greater number of females (173±28) emerged from the low stocking density compared to both the medium and high stocking densities (123±45 and 118±54, respectively). Peak adult emergence for the low and medium stocking densities occurred between days 22 and 25 post-hatch, whereas peak adult emergence occurred between days 30 and 33 for the high stocking density. Survival relative to the initial number of eggs stocked was significantly greater (P=0.007) in the low density treatment compared to that in either the medium or the high density treatments. Mean adult weight exhibited an inverse relationship with initial stocking densities. At test end, there was not a significant difference in the mean number of organisms surviving and emerging in the three density levels. The central tendency for number of organisms surviving for all three treatments was 504 organisms per tank (0.82 organisms cm−2). The results of this experiment suggest that an optimal egg stocking density of 1.0 egg cm−2 (∼600 eggs/tank) be used with the feeding rate identified. This would ensure uniform larvae at the appropriate developmental stage (2nd–3rd instar) needed for toxicological research/testing (e.g. 10 days post-hatch), as well as producing sufficient emergence of males and females for future culture establishment.

Preliminary investigation into impact of &lt;i&gt;Sitona lepidus&lt;/i&gt; adults on white clover seed production

A small plot trial was undertaken in the Waikato to determine the potential impact of Sitona lepidus adults on white clover seed production. Five densities of adult weevil were caged on 1 m2 plots from the time of peak adult emergence in November 1998 until harvest in late January 1999. In the laboratory, weevil adults were found to severely damage clover inflorescences when no leaves were present. Although feeding damage on leaves was highly visible in the field plots, with over 80% of the leaflets damaged at the highest density of 600 adults/m2, weevil adults were found to have no effect on flowering or seed production.

Efficacy of Talstar Flow Able and Granular as a Preventative Against Black Turfgrass Ataenius Adults, 1997

Abstract This trial was conducted at Campbell’s Scottish Highlands Golf Course, Salem, NH. Four replications of six treatments were applied to a bluegrass fairway on 15 May at peak adult emergence. Each plot was 147 ft2, arranged in an RCB form. The liquid formulations were applied with a 2-wheel bicycle-type boom sprayer equipped with 4 spray heads; each head was fitted with an 8004 flattened fan-type nozzle and a 50-mesh strainer. CO2 was the source of pressure applied at 40 psi. The volume of water and insecticide mix per plot was 1 gal/1000 ft2. All granulars were evenly applied with a large-holed, commercial salt shaker. The liquid formulations were allowed to dry; the granulars were watered in up to M". Weather conditions were as follows: air temp, 65°F; sky, overcast; wind, 10-15 mph. Soil conditions were as follows: temp (1-inch), 57°F; temp (2-inch), 55°F; texture, sandy loam; sand, 68%; silt, 24%; clay, 8%; moisture, 21.2%; organic matter, 5.2%; pH, 7. On 23 Jul, 2-ft2 sections of each plot were rated for live larvae; a Ryan sod cutter was used to cut into the turf.

Evaluation of Mach 2 and Merit Against First Generation Black Turfgrass Ataenius Larvae, 1997

Abstract This trial was conducted at Campbell’s Scottish Highlands Golf Club, Salem, NH. Five replications of 8 treatments were applied to a bluegrass fairway on 21 May one week past peak adult emergence. Each plot was 49 ft2; the plots were arranged in an RCB form. The liquid formulations were applied with a 2-wheel bicycle-type sprayer equipped with 4 spray heads; each head was fitted with an 8004 flattened fan-type nozzle with a 50-mesh strainer. All granulars were evenly applied with a large-holed commercial salt shaker. The volume of water and insecticide mix per plot was 2 gal/1000 ft2, applied by CO2 pressure at 40 psi. Natural rainfall irrigated the plots (0.1 inch). Weather conditions were as follows: air temp, 55°F; sky, partly cloudy; wind, 10 mph. Soil conditions were as follows: temp (1-inch), 55CF; texture, loam; sand, 66%; silt, 26%; clay, 8%; moisture, 20.95%; organic matter, 5.3%; pH, 7.2. On 22 Jul, a 2-ft2 section of each plot was rated for live larvae.

Effects of emergence date and maternal size on egg development and sizes of eggs and first-instar nymphs of a semelparous aquatic insect.

We examined whether or not sizes of eggs and offspring were related to emergence date or maternal size in a semelparous aquatic insect (the burrowing mayfly, Hexagenia) in which parental care is lacking and oviposited eggs are passively dispersed. We quantified the size of males and female imagos over the emergence span at a site on the Detroit River, Canada, and investigated relationships between emergence date and female size and (1) egg size and (2) size of first-instar nymphs. Although size of female imagos (H. limbata and H. rigida combined) declined significantly (P<0.025) over the emergence season, there was no significant relationship between body length and emergence date for males of either species. Males were significantly (P<0.001) smaller than females. H. limbata eggs, subsampled from three individuals from each of three size classes of female imagos collected on seven sampling dates, were measured using video image analysis. Eggs (n=100) oviposited by each of 63 H. limbata imagos were inspected daily for hatching. Newly hatched nymphs were removed, counted and measured. Egg size (P<0.001) and size of first-instar nymphs (P<0.001) varied significantly with emergence date, but not maternal size. The largest eggs and newly hatched nymphs occurred at peak emergence of adults. The synchronous release of larger (faster-sinking) eggs may result in reduced predation. Plasticity in egg development time and egg and nymph size may account for the ability of this taxon to recover from episodes of massive population reduction.

Control of Annual Bluegrass Weevil With Scimitar and Tempo, 1994

Abstract The experiment was conducted on a golf course fairway at the Rutland Country Club, Rutland, VT. Two formulations and 2 rates of Scimitar were compared to Tempo for adult control. The grass mixture was 30% bluegrass and 70% bentgrass. Sprays were applied on 20 May, at peak adult emergence. Plots were 6 X 9 ft, replicated 4 times in an RCB design. Each plot was separated by a 2 ft buffer. Sprays were applied with a CO2 backpack sprayer in 1.8 gal water/1000 ft2. Sprays were allowed to dry on. Plots were lightly irrigated 2-3 times per week. Plots were rated 23 Jun by removing three 0.1 ft2 plugs per plot and counting live larvae and pupae in the lab. Conditions at the time of treatment were: air temperature, 61.7°F; wind, 2 MPH; sky, clear; soil temperature, surface 78.1°F; thatch depth, 0.4 inch soil pH, 5.4; slope, 2%; soil texture, loam; soil organic matter, 7.9%; soil moisture, 25.5%.

Acalolepta vastator (Newman) (Coleoptera: Cerambycidae) Infesting Grapevines in the Hunter Valley, New South Wales 2. Biology and Ecology

ABSTRACTResearch into seasonal development of fig longicorn, Acalolepta vastator, demonstrated an annual life cycle with adults emerging between October and March, with a 12–21 d pre‐ovipositional period and longevity up to 6 months. Peak adult emergence occurred in January and February and male: female sex ratio varied between 1:1 and 1:2. Males outnumbered females in the early emergence period, whilst females were more numerous between January and March. Peak oviposition also occurred between January and March, with the base of young vine canes on main or secondary arms less preferred as an oviposition site (49%) than the trunk (51%). Data indicated that while, on average, 2.25 eggs were laid per female and up to six new egg laying sites may be selected per vine, only 0.8 mature larvae per vine survived. Egg hatch with a 60% success rate took 2–4 d and early larval development occurred on and just under the surface of the bark during the first four instars. Nine larval instars were identified with a mean total larval period of 38 weeks. Pupae were recorded from August and had a developmental period of around 20 d. No parasites or predators were recorded, but Beauvaria bassiana did infect a small number of larvae during wet conditions in the field. Data show that 75% of mature larvae occur in the trunk, with over 60% of all larvae completing their development in the area proximal to the fork in the grapevine.