Winged Adults Research Articles

Impacto do algodoeiro Bt na dinâmica populacional do pulgão-do-algodoeiro em casa de vegetação

O objetivo deste trabalho foi desenvolver um protocolo experimental para avaliar o impacto do algodoeiro Bt na bionomia e na escolha de plantas para colonização pelo pulgão-do-algodoeiro (Aphis gossypii). A bionomia do pulgão foi avaliada em casa de vegetação com insetos criados em gaiolas individuais com plantas de algodão Bt, da variedade DP 404 BG (Bollgard), ou sua isolinha não transformada DP 4049. Gaiolas contendo vasos com plantas de algodoeiro Bt e não-Bt foram usadas como arena de escolha, para a avaliação de preferência de adultos alados. O período pré-reprodutivo e reprodutivo, a longevidade, a curva de sobrevivência, a produção de prole total e diária por fêmea e a curva acumulada de produção de prole da população não apresentaram diferenças significativas. Não foi observada diferença na escolha de plantas para colonização por indivíduos alados, o que indica taxas equivalentes de colonização nas populações iniciais. O algodoeiro Bt não afeta a dinâmica populacional de A. gossypii e não aumenta seu potencial de risco como praga.

Juvenile hormone titres and winged offspring production do not correlate in the pea aphid, Acyrthosiphon pisum

Pea aphids, Acyrthosiphon pisum, reproduce parthenogenetically and are wing-dimorphic such that offspring can develop into winged (alate) or unwinged (apterous) adults. Alate induction is maternal and offspring phenotype is entirely determined by changes in the physiology and environment of the mother. Juvenile hormones (JHs) have been implicated in playing a role in wing differentiation in aphids, however until recently, methods were not available to accurately quantify these insect hormones in small insects such as aphids. Using a novel LC–MS approach we were able to quantify JH III in pea aphids that were either producing a high proportion of winged morphs among their offspring or mainly unwinged offspring. We measured JH III titres by pooling the hemolymph of 12 or fewer individuals (1 μL hemolymph) treated identically. Levels of JH ranged from 30 to 163 pg/μL. While aphids in the two treatments strongly differed in the proportion of winged morphs among their offspring, their JH III titres did not differ significantly. There was also no correlation between JH III titre and the proportion of winged offspring in induced aphids. This supports earlier findings that wing dimorphism in aphids may be regulated by other physiological mechanisms.

Changes in activity of superoxide dismutase and catalase within cereal aphids in response to plant o‐dihydroxyphenols

Abstract: Superoxide dismutase and catalase activity was found in the bird cherry‐oat aphid, Rhopalosiphum padi (L.) and the grain aphid, Sitobion avenae (F.). Among the aphid morphs studied, the highest activity of the antioxidant enzymes was noted for winged adults (alatae) and the lowest for wingless (apterae) ones. Higher activity of superoxide dismutase and catalase was observed in the polyphagous species R. padi that alternates between woody host plants and grasses. On some ocassions, activity of superoxide dismutase in cereal aphids was increased by twofold, when aphids were exposed to toxic plant o‐dihydroxyphenols. An opposite tendency was observed in case of activity of the catalase that was strongly reduced within body of phenolics‐treated insects. Among the plant allelochemicals studied, caffeic acid showed the strongest effect on the activity of the antioxidant enzymes of the cereal aphids. The experiments carried out indicate that antioxidant enzymes might play an important role in interactions between cereal aphids and their host plants.

Caracterização da transmissão do vírus do mosaico-das-nervuras do algodoeiro pelo pulgão Aphis gossyphii com relação à persistência e ao tempo necessário para inoculação

Na cultura do algodoeiro, Gossypium hirsutum L., o pulgão Aphis gossypii Glover, 1877 (Hemiptera: Aphididae) destaca-se pela transmissão do vírus do mosaico-das-nervuras do algodoeiro. O objetivo deste trabalho foi avaliar a persistência da transmissão desse vírus por A. gossypii e determinar o período necessário para sua inoculação. No ensaio de persistência, 20 pulgões ápteros virulíferos foram individualizados e transferidos diariamente para plantas de algodoeiro sadias. O período necessário para inoculação foi determinado em adultos ápteros e alados virulíferos, que permaneceram confinados isoladamente em plantas sadias por períodos de 40 segundos, 45 minutos, 1,5 hora, 3, 6, 12, 24 e 48 horas. Observou-se que 35% dos pulgões transmitiram o vírus por mais de cinco plantas sucessivamente, no ensaio de persistência. Verificou-se transmissão por um período máximo de 12 dias após a aquisição, o que caracteriza a relação vírus-vetor como persistente. Os adultos ápteros transmitiram o vírus para maior percentual de plantas (75,0%) quando o período de acesso à inoculação foi de 24 horas. Os alados transmitiram o vírus em todos os períodos de acesso à inoculação, com porcentagens variando de 5,0% (40 segundos) a 60,0% (48 horas). A persistência da transmissão do vírus pelo pulgão e o aumento na eficiência de transmissão em função do aumento do período de acesso à inoculação revelam que a transmissão é do tipo circulativa.

Response of Potato Aphid (Homoptera: Aphididae) to Synthetic Potato-Derived Colorado Potato Beetle (Coleoptera: Chrysomelidae) Attractant and Natural Potato Odor

A recently synthesized kairomone blend, based on the volatiles produced by potato (Solanum spp.) plants, has been demonstrated to be attractive to both adult and larval stages of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). It was subsequently formulated in a viscous inert carrier for field applications and showed potential for aggregating beetles in treated areas of the field. We investigated effects of this kairomone formulation on the potato aphid, Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae). The response of both winged and wingless adults to natural potato foliage and synthetic kairomone was tested in a Y-tube olfactometer. Aphid response to untreated potato foliage, foliage treated with the kairomone blend, and foliage treated with blank inert carrier also was tested in petri dishes. In addition, aphid densities on field plots treated with kairomone and blank inert carrier were compared with the control plots. The untreated potato foliage was found to be attractive to wingless, but not winged, potato aphids. In the olfactometer, the foliage treated with synthetic Colorado potato beetle kairomone was not attractive to either winged or wingless aphids. In petri dishes, aphids avoided leaflets treated with both kairomone formulation and its blank carrier. There was no statistical difference between any treatments compared in the field.

Response of Potato Aphid (Homoptera: Aphididae) to Synthetic Potato-Derived Colorado Potato Beetle (Coleoptera: Chrysomelidae) Attractant and Natural Potato Odor

A recently synthesized kairomone blend, based on the volatiles produced by potato (Solanum spp.) plants, has been demonstrated to be attractive to both adult and larval stages of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). It was subsequently formulated in a viscous inert carrier for field applications and showed potential for aggregating beetles in treated areas of the field. We investigated effects of this kairomone formulation on the potato aphid, Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae). The response of both winged and wingless adults to natural potato foliage and synthetic kairomone was tested in a Y-tube olfactometer. Aphid response to untreated potato foliage, foliage treated with the kairomone blend, and foliage treated with blank inert carrier also was tested in petri dishes. In addition, aphid densities on field plots treated with kairomone and blank inert carrier were compared with the control plots. The untreated potato foliage was found to be attractive to wingless, but not winged, potato aphids. In the olfactometer, the foliage treated with synthetic Colorado potato beetle kairomone was not attractive to either winged or wingless aphids. In petri dishes, aphids avoided leaflets treated with both kairomone formulation and its blank carrier. There was no statistical difference between any treatments compared in the field.

Genetic population structure and neighbourhood population size estimates of the caddisfly Plectrocnemia conspersa

Summary1. We used both genetic and ecological methods to evaluate the role of history and the scale of colonisation in structuring populations of the caddisfly Plectrocnemia conspersa. There was no genetic differentiation between sites up to 20 km apart, despite population sizes suggesting that genetic drift could create substantial variation at this scale.2. Genetic differentiation between populations separated by more than 20 km was greater than expected given the contrasting short‐range trend, and implied a neighbourhood population size that is implausibly small. Therefore, the evolutionary processes that affect the short‐range trend do not explain differentiation over greater distances.3. At small scales (<20 km), relatively short flights by winged adults spread over a number of generations could account for the spread of genes. For instance, dispersing individuals could found small (often temporary) populations, which may then grow and exchange genes with larger and more permanent local populations, amplifying the effects of the initial gene flow.4. Over larger scales (20–500 km), substantial gaps between regions containing suitable habitat patches could reduce the number of colonisation events. Genetic patterns at this scale may date from the time they were last colonised. Previous ecological studies have rarely examined the dynamics of aquatic insect populations over these larger geographical scales, yet these processes may be central to their persistence and spread.

The impact of individual ladybirds (Coccinella septempunctata, Coleoptera: Coccinellidae) on aphid colonies

Pea aphids (Acyrthosiphon pisum) have been reported to produce winged offspring in the presence of predatory ladybirds. These offspring may leave host plants by flight after they have developed into winged adults. The inter-generational nature of this response raises the question about the chances of survival of aphids developing in attacked colonies. We studied the behaviour of predatory ladybirds on host plants by releasing adult 7-spot ladybirds (Coccinella septempunctata) on bean plants hosting either no prey individuals or colonies of 10 or 30 pea aphids. Interactions between predator and prey were recorded until the ladybird left the plant. Ladybird patch residence time increased with the number of aphids present on a plant but beetles generally left a plant before all aphids were eaten. The time budget of the ladybirds revealed a high proportion of time not spent in feeding activities. Predation rate was about one aphid killed per 10min residence time in both treatments with aphid-infested plants. Aphids that survived an attack by the predator or that were alarmed when a conspecific was attacked often emigrated from the host plant, and their number was of the same magnitude as the number of aphids killed by the predator. On average, pea aphid numbers at the end of an experiment were reduced to less than a third of the initial value. The results of the experiment show that attack by single ladybirds does on average not cause immediate extinction of small aphid colonies. The short patch residence times of on average less than two hours show that a predator individual that induces winged-offspring production in an aphid colony will not any longer be present in the colony when the induced offspring mature. To understand the adaptiveness of predator-induced wing development in pea aphids the probabilities of subsequent attacks on an aphid colony need to be investigated.

Dynamique des populations d'Aphis gossypii Glover (Homoptera: Aphididae) sur concombre sous serre en zone côtière Marocaine

Aphis gossypii is one of the major pests of cucumber grown in greenhouses in the coastal areas of Morocco. A population dynamics study showed that A. gossypii populations might reach very high levels in June, causing economic damage to cucumber. The proliferation of A. gossypii on cucumber arises mainly from infestations by flying winged adults. Factors regulating the fluctuation of population of the species are discussed.

Comparative performance of two biotypes of Therioaphis trifolii (Monell) (Hemiptera: Aphididae) on clovers (Trifolium) and medics (Medicago)

Two genetically different biotypes of Therioaphis trifolii (Monell), spotted alfalfa aphid (SAA) and spotted clover aphid (SCA), occur in Australia. The potential host range of the two biotypes was determined by comparing their performance on eight species (12 cultivars) of clover (Trifolium) and two species (four cultivars) of medic (Medicago). Aphids were reared on excised trifoliate leaves on agar containing a soluble fertiliser. Parameters measured included initial host acceptance by adults, survival of first generation nymphs, incidence of winged adults and the weight and 4‐day fecundity of wingless adults. Spotted clover aphid clearly outperformed SAA on all 12 clover cultivars. Only on the three lucerne cultivars did SAA perform better than SCA. Barrel medic was a relatively unsuitable host for both aphids. The study revealed that SCA has a much wider host range than SAA and that it has the potential to be a serious threat to improved pastures in Australia where clover is a major component.

Dispersal and recruitment ofTasiagma ciliata(Trichoptera: Tasimiidae) in rainforest streams, south‐eastern Australia

1. This study examined genetic variation within and among populations of the caddis fly Tasiagma ciliata (Tasimiidae: Trichoptera) from rainforest streams in south‐east Queensland, Australia.2. Very low levels of genetic differentiation at large spatial scales, between subcatchments and between catchments, indicated that dispersal by the winged adults is widespread. However, significant genetic differentiation at the smallest spatial scale examined, within reaches in a single stream, suggested limited movement by larvae within streams.3. A patchy distribution of deviations from Hardy–Weinberg equilibrium and differences in patterns among allozyme loci suggested that populations in particular reaches were the result of only a few matings.4. These results are surprising, given the large numbers of larvae present within a single reach. We suggest that stochastic effects of recruitment may underlie much of the spatial and temporal variation in population numbers in these rainforest streams.

Patterns of foraging and distribution of bluegill sunfish in a Mississippi River backwater: influence of macrophytes and predation

Abstract— We studied the trophic interactions and spatial distributions of bluegills Lepomis macrochirus and largemouth bass Micropterus salmoides in a macrophyte bed in Lake Onalaska, a backwater lake in the upper Mississippi River. The diets of adult and age‐0 bluegills were similar and changed seasonally probably in response to changes in life stages of macroinvertebrates (i. e. emergence of winged adults). Diets and diel patterns of abundance of bluegill suggest that age‐O and adults were feeding in the vegetated, littoral zone. Predation by age‐O largemouth bass appears to influence use of vegetated habitat by age‐0 bluegills. In summer, when most age‐O bluegills were vulnerable to predation by age‐O largemouth bass, bluegill abundance was strongly correlated with vegetation biomass. In October and November, piscivory by age‐O largemouth bass was limited by gape. Consequently, the relationship between the abundance of age‐O bluegills and vegetation biomass was weakened because predation risk by age‐O largemouth bass was reduced.

Phenology and Food Preferences of Labidura truncata Kirby (Dermaptera: Labiduridae) in Western Victoria

ABSTRACTThe native earwig Labidura truncata was relatively abundant in pitfall traps at a site in cropping land in the Wimmera region of Victoria. It was an important predator and attacked a range of soft‐bodied insects, including pest species. Weekly pitfall‐trapping from April 1993 to March 1994 yielded the greatest numbers between November and February when both juveniles and adults were present. Peak numbers of winged adults were obtained in November and December, with initially greater numbers of males than females.

Effects of 2,2‐dimethylchromene derivatives on wing determination and metamorphosis in the pea aphid, Acyrthosiphon pisum

AbstractThe relationship between the structure of nineteen 2,2‐dimethylchromene derivatives and their effects on aphid morphogenesis were investigated in a pink clone of the pea aphid, Acyrthosiphon pisum (Harris). Three bioassay systems were used: (1) wing induction—the induction of winged (alate) progeny by winged adults that normally produce only wingless (apterous) daughters, (2) wing inhibition—the inhibition of production of winged progeny by wingless adults that had been crowd‐induced to promote the appearance of winged progeny, (3) the effect on metamorphosis—the production of precocious adults indicating a decrease in juvenile hormone titre or the induction of supernumerary moults indicating a juvenile hormone agonist effect. Compounds demonstrating wing‐promoting effects had short (≤2 carbon) side chains at the C6 and/or C7 positions while methylation of C5 tended to decrease this activity. Of the seven compounds inducing wing formation, three also inhibited the production of winged progeny. However, the compounds affecting metamorphosis, in particular promoting precocious adult development, were similar to those that promoted wing inhibition rather than those with wing inducing effects; they had alkoxy groups at C7 with lengths of ≥2 carbons.There is a stronger correlation between compounds interfering with metamorphosis (and therefore evidenced to be affecting juvenile hormone levels, a classic property of some 2,2‐dimethylchromene derivatives) and the promotion of wingless forms than the induction of winged forms. This finding is in contradiction to the idea that juvenile hormones are involved in promoting wingless forms. In addition, attempts to reduce the wing‐inducing properties of Precocene II (the most potent compound effecting wing induction) by subsequent treatment with juvenile hormone Ill or the juvenile hormone analogue, pyriproxyfen, were inconclusive and attempts to inhibit w ng formation with these two compounds atter crowding were also unsuccessful. The precise mode of action of the 2,2‐dimethylchromenes in relation to aphid wing induction remains unclear but it seems likely that the effect is not related to changes in juvenile hormone titres. © 1095 WiIey‐Liss, Inc.

Parasitism and Parasitoidism in Tarsonemina (Acari: Heterostigmata) and Evolutionary Considerations

Publisher Summary This chapter presents the routes of evolution from phoresy and physogastry toward parasitism and parasitoidism, and the distribution of parasites and parasitoids among the superfamilies and families of Tarsonemina. . Among the taxa of parasites and parasitoids in the superfamily Tarsonemoidea, only one adult female morph is known. However, among the all-parasitoid superfamily Pyemotoidea, only one adult female morph is known in the Acarophenacidae, but female dimorphism is recorded among at least some members of the Pyemotidae. For parasitoids, synchrony with the host phenology is vital to survival of the population because the host activity or progeny provide resources for the mites, and the young emerging winged adults are indispensable agents for the mites' disperal. Evolution toward parasitoidism appears to be correlated also with a capacity for the adult female to undergo physogastry, an immense swelling of her body while feeding on a host, before reproduction, to accommodate nearly simultaneous development of many embryos, so that they are even-aged in adulthood. Within the family Tarsonemidae, there are genera well documented as parasitoids and parasites, as well as predators. The Tarsonemina manifest various attributes that have acted in the course of evolution in favor of a diversity of symbiotic ways of life.

Keys to Soldier and Winged Adult Termites (Isoptera) of Florida

Illustrated identification keys are presented for soldiers and winged adults of the following 17 termite species known from Florida: Calcaritermes nearcticus Snyder, Neotermes castaneus (Burmeister), N. jouteli (Banks), N. luykxi Nickle and Collins, Kalotermes approximatus Snyder, Incisitermes milleri (Emerson), I. minor (Hagen), I. schwarzi (Banks), I. snyderi (Light), Cryptotermes brevis (Walker), and C. cavifrons Banks, Family Kalotermitidae; Coptotermes formosanus Shiraki, Reticulitermes flavipes (Kollar), R. hageni Banks, R. virginicus (Banks), and Prorhinotermes simplex (Hagen), Family Rhinotermitidae; and Amitermes floridensis Scheffrahn, Mangold, & Su, Family Termitidae.

Time-Specific Life Tables for Acyrthosiphon kondoi (Homoptera: Aphididae) in First Crop Alfalfa in Oklahoma

Time-specific life tables were developed for Acyrthosiphon kondoi Shinji in Oklahoma during growth of the first alfalfa crop in 1985 and 1986. In each year, population densities increased rapidly (from 200 aphids per stem) during a 2–3-wk period between early March and May. In the first interval of population growth each year, the observed rates were equivalent to the intrinsic rate of increase determined in laboratory studies. Although alatae were produced throughout the period of population growth, a rapid increase in the prevalence of this morph resulted in proportions of winged adults exceeding 90% just before population decline. A rapid decrease in numbers of A. kondoi from the peak densities occurred due to emigration of alatae and the resulting decrease in nymphal production. Although predaceous insects (primarily Hippodamia convergens Guerin-Meneville) were present in moderate numbers (up to 0.2 individuals per stem), there was little evidence of limitation imposed on the growth rates of the aphid population. We observed no parasitized or diseased aphids and it appeared that natural controls were not effective in slowing the rapid growth of populations and preventing outbreaks during our study. Except for emigration of alatae, no factors were identified that reduced population densities by detectable amounts.

Bioavailability of sediment‐sorbed and aqueous surfactants to Chironomus riparius (midge)

AbstractThe bioavailability of sediment‐sorbed and soluble fractions of three surfactants were compared in egg hatchability and partial life cycle chronic bioassays with the midge Chironomus riparius. The chemicals tested were linear alkyl (dodecyl) benzene sulfonate (LAS), dodecyl trimethyl ammonium chloride (TMAC) and distearyl dimethyl ammonium chloride (DSDMAC). Midge eggs exposed to ranges of surfactant concentrations in water were monitored for hatching success and posthatch survival. No significant reductions in egg hatching were observed at the highest concentrations tested: 18.9 mg/L LAS, 21.5 mg/L DSDMAC and 15.4 mg/L TMAC. Newly hatched larvae were more sensitive than eggs; respective 72‐h LC50 concentrations (48‐h for TMAC) were 2.2, 11.3 and 14.6 mg/L. In partial life cycle chronic bioassays in sediment/water test systems, percentages of winged adults emerging after continuous exposure of larvae and pupae to doses of each surfactant were determined. Exposure concentrations in sediment, interstitial water and overlying water were monitored by 14C liquid scintillation counting. Lowest observed effect concentrations (LOECs) of sediment‐spiked surfactants were 319 to 993 μg/g (dry weight) LAS, 876 to 2,708 μg/g DSDMAC and >3,084 μg/g TMAC (highest concentration tested). Corresponding no observed effect concentrations (NOECs) were 319 μg/g LAS, 876 μg/g DSDMAC and 3,084 μg/g TMAC. The NOECs are approximately 100, 1,000 and 10,000 times greater than respective NOECs of the solubilized materials, and exceed levels of these materials measured in the environment. The results indicated that adsorption onto sediment significantly mitigates surfactant bioavailability to Chironomus.

Timing of emergence of males and females of Ephoron shigae (Ephemeroptera: Polymitarcyidae)

SUMMARY. 1. The winged adults of Ephoron shigae swarming over the water surface were collected by successive random sweeps during their daily emergence period, and the changes in sex and stage composition were examined, in the lower reach of the Asahi River in western Japan.2. The emergence occurred mainly during a 11/2 h period beginning some time after sunset. Male sub‐imagos emerged synchronously and moulted to imagos in a 25 min period immediately prior to an abrupt increase of female emergence.3. This timing of male emergence may be considered the result of selection of males to decrease the risk of death before mating, and for all the males to have an equal opportunity to mate.

Seasonal and diurnal changes in emergence of Potamanthodes kamonis in a stream of central Japan (Ephemeroptera: Potamanthidae).

Seasonal and diurnal changes in emergence of P. kamonis were studied using a light trap and emergence traps in a stream of central Japan in 1978-1980. The main emergence period was from mid-July to the end of September. Most of the winged adults collected were subimagos. Subimagos gradually decreased in size during the emergence periods in 1979 and 1980, but this tendency was not so clear in 1978. The emergence continued from sunset to sunrise each day in the middle of the emergence period, but it ceased far earlier before sunrise on the early and later days of the period. The daily emergence time of females was somewhat earlier than that of males, and the proportion of males to females gradually increased toward sunrise.