Alatoid Nymphs Research Articles

First record of antipredator behavior in the gall‐forming aphid Mordwilkoja vagabunda

AbstractThe gall‐forming aphid Mordwilkoja vagabunda has been an out‐group in molecular studies of the evolution of social behavior in the Pemphigus genus, but Mordwilkoja aphids have not previously been assayed for social behavior, such as altruistic defense. This study reports experiments carried out in July in Ithaca, NY, in which nymphs (immature aphids) of M. vagabunda were video‐recorded under a stereomicroscope while they encountered pyralid moth larvae in a plastic arena. Mordwilkoja vagabunda nymphs of all instars used their legs to claw moth larvae while pressing their rostrums against the larvae, possibly to pierce the cuticle. Many of the attacking aphids were alatoid nymphs, rather than the specialized first‐instar soldiers typically observed in Pemphigus species. Mordwilkoja vagabunda nymphs moved in bursts that sometimes became synchronized among several aphids in the same vicinity. These synchronized, rhythmic movements may be antipredator defense strategies comparable to the collective twitching and kicking response observed in colonies of Aphis nerii and other aphid species. Defensive behaviors by M. vagabunda nymphs may be altruistic fortress defense strategies, which maximize the inclusive fitness of the clone.

Effect of Binodoxys communis parasitism on flight behavior of the soybean aphid, Aphis glycines

Many aphid species possess wingless (apterous) and winged (alate) stages, both of which can harbor parasitoids at various developmental stages. Winged aphids bearing parasitoid eggs or young larvae can potentially still engage in long-distance flights and thereby facilitate parasitoid dispersal, which has important implications for biological control of aphids by parasitoids. In this study, we determined the effect of parasitism by Binodoxys communis (Hymenoptera: Braconidae) on wing development and flight of the summer alate stage of the soybean aphid, Aphis glycines (Hemiptera: Aphididae), and quantified the effect of aphid flight duration on subsequent B. communis development. Parasitism by B. communis was allowed at alatoid 3rd (L3) and 4th instar (L4) nymphal stages of A. glycines and subsequent aphid flight was measured using a computer-monitored flight mill. Only 25% of aphids parasitized as L3 alatoid nymphs produced normal winged adults, compared to 100% of L4 alatoids. While flight performance of aphids that had been parasitized as 4th-instar alatoid nymphs 24 or 48h prior to testing was similar to that of unparasitized alates of identical age, it declined sharply for alates that had been parasitized as 4th-instar alatoid nymphs 72 and 96h prior to testing. Parasitoid larval and pupal development times, percent mummification and adult emergence rates did not differ between treatments in which aphids had flown over varying durations. Our results have implications for natural biological control of A. glycines in Asia and classical biological control of the soybean aphid in North America.

Parasitism of Autumnal Morphs of the Soybean Aphid (Hemiptera: Aphididae) by Binodoxys communis (Hymenoptera: Braconidae) on Buckthorn

Abstract The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is both heteroecious and holocyclic, seasonally alternating between buckthorn (Rhamnus spp.), (the primary, overwintering host) and soybean, Glycine max (L.) Merr. (the secondary host). Recently, a classical biological control program for this invasive pest has been implemented in North America using the Asian aphidiine braconid wasp Binodoxys communis Gahan. Two critical, related questions regarding the overwintering biology of B. communis are 1) does the parasitoid maintain fidelity to A. glycines throughout the aphid life cycle and follow it to its primary host; and, if it does, 2) is parasitoid migration facilitated by phoretic movement within buckthorn-specific winged aphids? In the laboratory, we compared B. communis parasitism on several different autumnal morphs of A. glycines: winged gynoparae (fall migrants) and their oviparous offspring on buckthorn, fourth-instar alatoid nymphs that would form either gynoparae or summer migrants on soybean, and third-instar gynoparous alatoid nymphs on soybean. We also introduced gynoparae and B. communis onto caged buckthorn plants in southeastern Minnesota to examine autumnal parasitism under natural conditions. In both the laboratory and field, parasitism rates of oviparae were much higher than those of gynoparae. In addition, B. communis rarely completed development on fourth-instar alatoid nymphs. Although wasps successfully developed on third-instar gynoparous nymphs, these hosts mummified before forming wings. These results suggest that although at least one buckthorn-specific morph of A. glycines seems suitable for B. communis parasitism, it is unlikely that alate-mediated dispersal of immature parasitoids is an adaptive strategy to locate Rhamnus in this species.

Effect of parasitism on flight behavior of the soybean aphid, Aphis glycines

Many aphid species possess wingless (apterous) and winged (alate) stages, both of which can harbor parasitoids at various developmental stages. Alates can either be parasitized directly or can bear parasitoids eggs or larvae resulting from prior parasitism of alatoid nymphs. Winged aphids bearing parasitoid eggs or young larvae eventually still engage in long-distance flights, thereby facilitating parasitoid dispersal. This may have a number of important implications for biological control of aphids by parasitoids. In this study, we determined the effect of parasitism by Aphelinus varipes (Hymenoptera: Aphelinidae) on wing development and flight of the soybean aphid, Aphis glycines (Hemiptera: Aphididae). We also quantified the influence of aphid flight distance on subsequent A. varipes development. Parasitism by A. varipes was allowed at different A. glycines developmental stages (i.e., alatoid 3rd and 4th-instar nymphs, alates) and subsequent aphid flight was measured using a computer-monitored flight mill. Only 35% of aphids parasitized as L3 alatoid nymphs produced normal winged adults compared to 100% of L4 alatoids. Flight performance of aphids parasitized as 4th-instar alatoid nymphs 24 or 48h prior to testing was similar to that of un-parasitized alates of identical age, but declined sharply for alates that had been parasitized as 4th-instar alatoid nymphs 72 and 96h prior to testing. Flight performance of aphids parasitized as alate adults for 24h was not significantly different from un-parasitized alates of comparable ages. Flight distance did not affect parasitoid larval or pupal development times, or the percent mummification of parasitized aphids. Our results have implications for natural biological control of A. glycines in Asia and classical biological control of the soybean aphid in North America.

Parasitism of the soybean aphid,Aphis glycinesbyBinodoxys communis: the role of aphid defensive behaviour and parasitoid reproductive performance

The Asian parasitoid, Binodoxys communis (Gahan) (Hymenoptera: Braconidae), is a candidate for release against the exotic soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), in North America. In this study, we examined preferences by B. communis for the different developmental stages of A. glycines and investigated consequences of these preferences for parasitoid fitness. We also determined to what extent aphid defensive behaviours mediate such preferences. We found that B. communis readily attacks and successfully develops in the different A. glycines developmental stages. Binodoxys communis development time gradually increased with aphid developmental stage, and wasps took longest to develop in alates. An average (+/-SE) of 54.01+/-0.08% of parasitized A. glycines alatoid nymphs transformed into winged adult aphids prior to mummification. No-choice assays showed a higher proportion of successful attacks for immature apterous A. glycines nymphs compared to adults and alatoid nymphs. Also, choice trials indicated avoidance and lower attack and oviposition of adults and alatoid nymphs. The different aphid stages exhibited a range of defensive behaviours, including body raising, kicking and body rotation. These defenses were employed most effectively by larger aphids. We discuss implications for the potential establishment, spread and biological control efficacy of A. glycines by B. communis in the event that it is released in North America.

Alate Production of Soybean Aphid (Homoptera: Aphididae) in Minnesota

The soybean aphid, Aphis glycines Matsumura, is a serious pest in Midwestern soybean, Glycine max L. Merrill, and has the potential to colonize a large geographic range throughout a single growing season. Our objectives were to describe colonization patterns on a statewide spatial and temporal scale, examine the changing proportion of winged forms throughout a season, and assess photoperiod as a potential trigger for alate production. In Minnesota, we define initial colonization as the period of time during the early vegetative growth when alates were present and alatoid nymphs were absent on soybean. Initial colonization during 2002 and 2003 was ∼2 wk. On average across Minnesota, summer migrants were first produced when most fields were at the initial flowering stages in 2002. In 2003, an outbreak year, initial detection of summer migrants occurred earlier during vegetative stages before flowering. The significant increase in the proportion of all potential migratory forms (i.e., alatoid nymphs and adults) occurred during the beginning of seed set for both years. During seed set, the mean proportion of alate A. glycines was 0.15 ± 0.04 (SE) in 2002 and 0.16 ± 0.06 in 2003. The mean proportion of alatoid nymph A. glycines was 0.14 ± 0.04 in 2002 and 0.29 ± 0.04 in 2003 during seed set. The total mean proportion of migratory forms was higher when the critical L:D photoperiod was 14.5:9.5 h/d. A regression analysis also indicated the proportion of winged A. glycines increased with decreasing photoperiod.

Alate production by aphids on sugar beet: how likely is the evolution of sugar beet-specific biotypes?

Summary1. Aphid clones that feed on the same plant species for many generations oftendevelop biotypes specifically adapted to the particular host-plant. Such biotypescan be particularly damaging to crops. In the case of sugar beet Beta vulgaris,which is not available for colonization for parts of the year, aphids must migrateinto and out of the crop each year if host-specific biotypes are to evolve. The likeli-hood of biotypes evolving to be specifically adapted to sugar beet was examinedand the results are discussed in relation to the control of aphids on this crop.2. The frequency and causes of alate production by aphids on sugar beet wereinvestigated by examining natural field populations, manipulated field populationsand laboratory populations. Data from these studies were used in a model that esti-mated the probability of an aphid clone on sugar beet successfully migrating fromthe crop, surviving the winter and migrating back on to the crop the followingyear.3. In 2 years out of 4, no alatoid nymphs of the aphids Myzus persicae andMacrosiphum euphorbiae were produced on naturally infested crops of sugar beet,and negligible numbers were produced in the other 2 years.4. In spring, a much greater proportion of the My. persicae population was alatoidon oilseed rape Brassica napus than on sugar beet. Similarly in laboratory studies,a greater proportion of My. persicae was alatoid on Chinese cabbage Brassica peki-nensis than on sugar beet at the same levels of crowding. The colour of the alatoidnymphs reared on Chinese cabbage indicated that it was a more suitable host thansugar beet and this might account for the greater alate production. Infection ofsugar beet with beet yellows virus did not increase alate production by My. persi-cae.5. A deterministic model showed that the probability of an alate My. persicaemigrating from sugar beet and recolonizing sugar beet the following year would, atbest, be only 1 in 40000.6. As there is negligible transfer of genetic material from year to year, we suggestthat biotypes of My. persicae specifically adapted to sugar beet are unlikely toevolve. As a result, if particular aphicides were only used on sugar beet, resistanceto those aphicides would be unlikely to evolve because any new resistance wouldnot be transmitted from year to year.Key-words: alatoid nymphs, Aphis fabae, BMYV, BYV, host races, Macrosiphumeuphorbiae, Myzus persicae, oilseed rape.Journal of Applied Ecology (2000) 37, 40–51

Seasonal Population Prevalence of Aphids with Special Reference to the Production of Alatoid Nymphs in a Potato Field in Hokkaido, Japan

Seasonal Population Prevalence of Aphids with Special Reference to the Production of Alatoid Nymphs in a Potato Field in Hokkaido, Japan

A SURVEY OF RHOPALOSIPHUM PADI (L.) (HEMIPTERA: APHIDIDAE) AND OTHER WHEAT-INFESTING CEREAL APHIDS FLYING OVER SOUTH AUSTRALIA IN 1989

In 21 trap locations across South Australia Rhopalosiphum padi was the most commonly trapped species of cereal aphid. Metopolophium dirhodum (Walker) and Sitobion nr fragariae were rarely trapped at any of the locations other than the Waite Institute. The trap catches of R. padi peaked twice. The first, an autumn peak, began in late April and continued through until the end of May, coinciding with the production of alatoid nymphs in perennial grass pastures. The second, winter peak commenced in July and continued through to the end of sampling, coinciding with alatoid nymph production in annual volunteer grasses and wheat crops. M. dirhodum and S. nr fragariae had only one peak which occurred in winter-spring.

Population Dynamics of Rhopalosiphum padi (Homoptera: Aphididae) in Corn in Relation to Barley Yellow Dwarf Epidemiology in Southwestern Idaho

Population dynamics of Rhopalosiphum padi (L.) in seed and silage corn were investigated from 1981 through 1985 in southwestern Idaho. Aphid population development was divided into four phases: an immigration period, a lag period, a period of rapid increase where aphid numbers reached several million per hectare, and an emigration period characterized by an increase in alatoid nymphs and alatae. Just before peak aphid densities occurred, prereproductive development time for apterous R. padi was 9.9 ± 0.9 d ($\bar x$ ± SEM) in seed corn and 9.6 ± 0.5 d in silage corn. The reproductive rate of apterae during this same period was 36.6 ± 11.0 nymphs in seed corn and 9.8 ± 2.9 nymphs in silage corn. Flight activity, as indicated by suction trap data, peaked in July and again from September through October or November. These two peaks corresponded with the immigration and emigration of R. padi detected in corn. Residents on corn were assayed for transmission of barley yellow dwarf virus, and the mean frequencies were 36% in 1983, 4% in 1984, and 2% in 1985. Migrant R. padi collected in a modified suction trap in 1985 showed a mean transmission frequency of 6%. Fall migrant R. padi in corn had a mean life span of ≈14 d and a maximum life span of 41 d, which is sufficient time for fall-planted cereals to become infested with these migrants. Monthly maximum and minimum temperatures for epidemic and nonepidemic years differed most in December, January, and February, suggesting a possible temperature–disease relationship.

Bionomics of Aphis gossypii1 on Resistant and Susceptible Cantaloupe

Bionomics of the melon aphid, Aphis gossypii Glover, were studied on resistant and susceptible cantaloupe, Cucumis melo L., plants. In the field, there was no difference between the age distributions of populations on resistant and susceptible plants. However, late in the season, a significantly greater proportion of the population on susceptible plants consisted of alatoid nymphs. Alate adults confined to resistant plants in the greenhouse suffered significantly greater mortality and produced only ca. 25% as many progeny as their counterparts on susceptible plants. Apterous aphids on resistant plants were smaller, had a significantly longer prereproductive period, and significantly shorter reproductive and postreproductive periods than those on susceptible plants. Approximately equal percentages of aphids on resistant and susceptible plants produced offspring, but the <mml:math><mml:mrow><mml:mover><mml:mtext>x</mml:mtext><mml:mo>¯</mml:mo></mml:mover></mml:mrow></mml:math> fecundity on the former was only ca. ⅓ that on the latter. This was attributable to both a lower reproductive rate among reproducing aphids and a higher mortality rate during the reproductive period on resistant than on susceptible plants. Populations of A. gossypii were maintained for up to 5 generations on resistant plants, with no danger of extinction.

The Distribution and Seasonal History of Amphorophora agathonica1 Hottes on ‘Latham’ Red Raspberry2

Most Amphorophora agathonica Hottes observed during 1971 and 1972 on ‘Latham’ red raspberry were located on the primocanes. Relatively few were seen on the floricanes. Alatoid nymphs were most abundant in late June, several weeks prior to the peaks in population density. Their appearance at this time implies that the greatest natural primary spread of raspberry mosaic from cultivated plantings may be expected in late June and early July. Nymphs collected in the field on Sept. 22 and 29 developed into oviparae.

INSECT DEVELOPMENTAL INHIBITORS: EFFECT OF REDUCTION AND DELAY CAUSED BY JUVENILE HORMONE MIMICS ON THE PRODUCTION OF WINGED MIGRANTS OF MYZUS PERSICAE (HEMIPTERA: APHIDIDAE) ON PEACH TREES

AbstractInsect developmental inhibitors applied to colonies of the green peach aphid, Myzus persicae (Sulzer), on peach trees in early May reduced the production of winged migrants as much as 75% and delayed migration for as long as 15 days. However, these compounds affected mainly the alatoid nymphs and not the reproductive adults; therefore, apterous aphids would be available as prey to the natural enemies that are present on peach trees in the spring. A reduction in the number of aphid migrants and a delay in their migration from peach trees would result in a subsequent reduction in the number of aphids produced on diseased secondary hosts and a delay in the migration of these aphids to host crops. In most cases, this would result in an increase in yield and an economic gain to the growers.