Treatment thresholds for stink bugs (Hemiptera: Pentatomidae) in cotton

The green stink bug, Acrosternum hilare (Say), the southern green stink bug, Nezara viridula (L), and the brown stink bug, Euschistus servus (Say), were predominant phytophagous Pentatomidae detected during 1995-1997 in cotton in South Carolina. These species occurred in similar numbers in conventional and transgenic cotton 'NuCOTN33B', containing the gene for expression of CryIA(c) delta-endotoxin of Bacillus thuringiensis Berliner variety kurstaki. Adult stink bugs moved into cotton from wild and cultivated alternate hosts during July, and reproducing populations usually were detected in cotton from late July into September. Applications of either methyl parathion (0.56 kg [AI]/ha) directed for stink bugs or lambda-cyhalothrin (0.037 kg [AI]/ha) or cyfluthrin (0.056 kg [AI]/ha) for control of cotton bollworm, Helicoverpa zea (Boddie), provided effective control of pentatomids in NuCOTN33B or conventional 'DP5415' and increased yields compared with untreated plots. Fiber quality did not differ among treated or untreated plots of NuCOTN33B. The ground-cloth technique was used to estimate populations of stink bugs, and data indicated that treatment at one bug per 2 m of row adequately protected cotton from yield loss due to stink bug damage. Observations on boll damage indicated that treatment might be necessary if >20-25% reveal internal symptoms of feeding injury during mid- to late season. More detailed damage thresholds should be developed to complement an approach based on population monitoring. This study validated current recommendations for management of pentatomids in cotton, demonstrated the necessity of threshold use for stink bugs in transgenic cultivars expressing endotoxin from B. thuringiensis, and provided insight into further development of management options for pentatomids in the crop.     

Monitoring stink bugs (Hemiptera: Pentatomidae) in mid-Atlantic apple and peach orchards

Pyramid traps coated with "industrial safety yellow" exterior latex gloss enamel paint and baited with Euschistus spp. aggregation pheromone, methyl (2E,4Z)-decadienoate captured more stink bugs than all other baited and unbaited trap types in both apple and peach orchards in 2002 and 2003. Commercial sources of dispensers of methyl (2E,4Z)-decadienoate deployed in association with pyramid traps had a significant impact on trap captures. Captures in pyramid traps were four-fold greater when baited with lures from IPM Technologies, Inc. (Portland, OR) than with lures from Suterra (Bend, OR). Variation in yellow pyramid trap color ("industrial safety yellow" and "standard coroplast yellow") and material (plywood, plastic, and masonite) did not affect trap captures. Brown stink bug was the predominant species captured (58%), followed by dusky stink bug, Euschistus tristigmus (Say) (20%); green stink bug, Acrosternum hilare (Say) (14%); and other stink bugs (Brochymena spp. and unidentified nymphs) (8%). Captures in baited pyramid traps were significantly correlated with tree beating samples in both managed and unmanaged apple orchards and with sweep netting samples in the unmanaged apple orchard. However, problems associated with trapping mechanisms of pyramid trap jar tops and jar traps likely resulted in reduced captures in baited traps. Improved trapping mechanisms must be established to develop an effective monitoring tool for stink bugs in mid-Atlantic orchards.     

Morphology of the antennal sex-gland in male Trissolcus basalis (Woll.) (Hymenoptera : Scelionidae), an egg parasitoid of the green stink bug,Nezara viridula (Hemiptera : Pentatomidae)

The 5th antennomere, beginning with the scape, of the male Scelionidae antenna has been referred to as a sex-segment due to its morphological and presumed sexual function. A study of the sex-segment of the parasitoid, Trissolcus basalis (Woll.) (Hymenoptera : Scelionidae) revealed a single ventral peg that is involved in releasing a secretion from an exocrine gland located in the antennomere. This is a “class 3” exocrine gland and the secretion appears to be partially proteinaceous since it is susceptible to protease digestion. Although the function of the sex-segment and gland remains unknown, the suggestion that it is involved in courtship is supported. Some sex-segment processes of other Scelionidae are also considered.     

Composition and abundance of stink bugs (Heteroptera: Pentatomidae) in corn

The species composition and abundance of stink bugs (Heteroptera: Pentatomidae) in corn, Zea mays L., was determined in this on-farm study in Georgia. Seven species of phytophagous stink bugs were found on corn with the predominant species being Nezara viridula (L.) and Euschistus servus (Say). All developmental stages of these two pests were found, indicating they were developing on the corn crop. The remaining five species, Oebalus pugnax pugnax (F.), Euschistus quadrator (Rolston), Euschistus tristigmus (Say), Euschistus ictericus (L.), and Acrosternum hilare (Say), were found in relatively low numbers. Adult N. viridula were parasitized by the tachinid parasitoid Trichopoda pennipes (F.). There was a pronounced edge effect in distribution of stink bugs in corn. Population dynamics of N. viridula and E. servus were different on early and late-planted corn. Oviposition by females of both stink bug species occurred in mid-to-late-May and again mid-to-late-June in corn, regardless of planting date. In early planted fields, if stink bug females oviposited on corn in mid-July, the resulting nymphs did not survive to the adult stage in corn because ears were close to physiological maturity and leaves were senescing. Density of stink bug adults in early planted corn was relatively low throughout the growing season. In late-planted corn, females of both stink bug species consistently laid eggs in mid-to-late-July on corn with developing ears. This habitat favored continued nymph development, and the resulting adult population reached high levels. These results indicate that corn management practices play a key role in the ecology of stink bugs in corn agroecosystems and provide information for designing management strategies to suppress stink bugs in farmscapes with corn.     

Influence of corn on stink bugs (Heteroptera: Pentatomidae) in subsequent crops

In southeastern United States farmscapes, corn, Zea mays L., is often closely associated with peanut, (Arachis hypogaea L.), cotton, (Gossypium hirsutum L.), or both. The objective of this 3-yr on-farm study was to examine the influence of corn on stink bugs (Heteroptera: Pentatomidae), Nezara viridula (L.), and Euschistus servus (Say), in subsequent crops in these farmscapes. Adults of both stink bug species entered corn first, and seasonal occurrence of stink bug eggs, nymphs, and adults indicated that corn was a suitable host plant for adult survival and nymphal development to adults. Stink bug females generally oviposited on cotton or peanut near the interface, or common boundary, of the farmscape before senescence of corn, availability of a new food, or both. Adult stink bugs dispersed from crop to crop at the interface of a farmscape in response to senescence of corn, availability of new food, or both. In corn-cotton farmscapes, adult stink bugs dispersed from senescing corn into cotton to feed on bolls (fruit). In corn-peanut farmscapes, adult stink bugs dispersed from senescing corn into peanut, which apparently played a role in nymphal development in these farmscapes. In the corn-cotton-peanut farmscape, stink bug nymphs and adults dispersed from peanut into cotton in response to newly available food, not senescence of peanut. Stink bug dispersal into cotton resulted in severe boll damage. In conclusion, N. viridula and E. servus are generalist feeders that exhibit edge-mediated dispersal from corn into subsequent adjacent crops in corn-cotton, corn-peanut, and corn-peanut-cotton farmscapes to take advantage of suitable resources available in time and space for oviposition, nymphal development, and adult survival. Management strategies for crops in this region need to be designed to break the cycle of stink bug production, dispersal, and expansion by exploiting their edge-mediated movement and host plant preferences.     

Field trials of aggregation pheromones for the stink bugs Chlorochroa uhleri and Chlorochroa sayi (Hemiptera: Pentatomidae)

In field trials, adult Chlorochroa uhleri (St?l) (Heteroptera: Pentatomidae) of both sexes were caught in significant numbers in cylindrical screen traps baited with gray rubber septum lures loaded with the main component of the male-produced pheromone, methyl (E)-6-2,3-dihydrofarnesoate. Addition of the two possible minor components of the pheromone, methyl (E)-5-2,6,10-trimethyl-5,9-undecadienoate and methyl (2E,6E)-farnesoate, did not affect attraction. Combining the pheromone with different concentrations of volatiles mimicking the odors of a known host plant, alfalfa (Medicago sativa L.), had no significant effect on attraction of adult bugs, whereas combining the pheromone with the pheromones of two sympatric stink bug species, Chlorochroa sayi (St?l) and Euschistus conspersus Uhler, decreased trap captures, suggesting interference between the pheromones. Small numbers of Chlorochroa ligata (Say) adults also were attracted, but numbers caught were too low to allow statistical comparisons between lure blends. In field trials with C. sayi, all three of the male-specific pheromone compounds [methyl geranate, methyl citronellate, and methyl (E) -6-2,3-dihydrofarnesoate] were required for optimal attraction. As with C. uhleri, adults of both sexes were attracted to pheromone lures in approximately equal numbers. Because of the decreased volatility (=release rate) of methyl (E)-6-2,3-dihydrofarnesoate in comparison with the other two, lower molecular weight pheromone components, lures needed to be loaded with a disproportionately high amount of methyl (E)-6-2,3-dihydrofarnesoate to obtain the best trap catch. There was no indication that the pheromone components of C. uhleri or E. conspersus interfered with the attractiveness of the C. sayi pheromone in lures containing a blend of all three pheromones.     

Efficacy of selected insecticides against eggs of Euschistus servus and Acrosternum hilare (Hemiptera: Pentatomidae) and the egg parasitoid Telenomus podisi (Hymenoptera: Scelionidae)

Brown stink bug, Euschistus servus (Say), and green stink bug, Acrosternum hilare (Say) (Hemiptera: Pentatomidae), are major agricultural pests. Although various insecticides are used to control nymphs and adults, little is known about how they affect eggs. Laboratory bioassays and field trials were conducted to determine the efficacy of common field rates of acephate, lamda-cyhalothrin, spinosad, and thiamethoxam on developing E. servus and A. hilare eggs, as well as Telenomus podisi Ashmead (Hymenoptera: Scelionidae) parasitoids developing in E. servus eggs. In laboratory bioassays, egg masses were dipped into insecticide and water solutions and assessed for mortality after 2 wk. In the field trials, egg masses on a cloth section were pinned to leaves in each plot ofa randomized complete block and returned to the laboratory 24 h after exposure to insecticide sprays. Mortality was assessed after 2 wk. In dip bioassays, there was a significant effect of insecticide treatment on A. hilare eggs with all insecticides resulting in greater mortality than the water control. However, no effect of treatment occurred in the field with A. hilare or for E. serous eggs in both the laboratory bioassays and the field trials. In contrast, developing T. podisi parasitoids showed significant mortality when exposed to all insecticide treatments, when dipped or field-treated. Spinosad and lamda-cyhalothrin treatments resulted in 100% mortality of T. podisi, and acephate resulted in greater mortality than thiamethoxam. Our results suggest that there is relatively little efficacy from insecticide sprays on stink bugs developing in eggs but that mortality of egg parasitoids may be significant.     

Cold storage of the egg parasitoids Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead (Hymenoptera: Scelionidae)

Adults of Trissolcus basalis and Telenomus podisi were stored either at 15 or 18 °C after their immature development had been completed at 18 or 25 °C. Longevity of the parasitoids in the storage temperatures was evaluated, as well as fecundity and longevity following their return to 25 °C after different periods in reproductive diapause. Temperature during immature development influenced female longevity and highest mean longevity was obtained for females that developed to the adult stage at 25 °C and then were stored at 15 °C (ca. 13 months for T. basalis and 10 months for Te. podisi). For adults of T. basalis that developed at 25 °C, storage periods of 120 or 180 days at 15 or 18 °C did not affect fecundity. The fecundity of T. basalis females that developed at 18 °C and were stored for 120 days at 15 or 18 °C was not affected; however, after remaining for 180 days, fecundity was reduced in ca. 30 and 50%, respectively. Storage of Te. podisi adults at 15 or 18 °C significantly reduced fecundity. It is concluded that adults of T. basalis can be stored in the adult stage at 15 or 18 °C between two soybean crop seasons for mass production purposes, aiming the biological control of stink bugs.     

Seasonal cycles in stink bugs (Heteroptera,Pentatomidae) from the temperate zone: Diversity and control

The paper reviews the diversity of seasonal cycles known in stink bugs (Heteroptera, Pentatomidae) from the temperate zone and is based on the data of 43 pentatomid species studied in detail up to date (Saulich and Musolin, 2011). All the seasonal cycles realized by pentatomids in the temperate zone can be divided into two large groups: univoltine and multivoltine cycles. In univoltine cycles, only one generation is annually realized. However, univoltinism of a particular species or population can be ensured by different mechanisms: its control can be endogenous (involving an obligate diapause) or exogenous (environmental, involving a facultative diapause). Furthermore, endogenously controlled univoltine seasonal cycles can include obligate embryonic (egg) diapause (e.g., Picromerus bidens and Apateticus cynicus), obligate nymphal diapause (e.g., Pentatoma rufipes) or obligate adult (reproductive) diapause (e.g., Palomena prasina, Palomena angulosa, and Menida scotti). Exogenously controlled seasonal cycles are more flexible. Many species that are multivoltine in the subtropical or warm temperate zones are univoltine further polewards. In this case, their univoltinism is controlled exogenously, or environmentally. The mechanism often involves such seasonal adaptations as photoperiodic response of facultative winter diapause induction with a high thermal optimum (e.g., Arma custos and Dybowskyia reticulata) or a high critical threshold of winter diapause induction response (e.g., Graphosoma lineatum). The seasonal cycles of some species include not only winter diapause (hibernation) but also summer diapause (aestivation). The diapausing stage can be the same (e.g., Nezara antennata has facultative adult winter and summer diapauses) or different (e.g., Picromerus bidens survives winter in obligate embryonic diapause and spends the hottest period of summer in facultative adult aestivation). All the multivoltine cycles follow the same general pattern, with one, two, or even more directly breeding generation(s) followed by a generation that enters winter diapause. However, this sequence may be complicated by incorporation of specific seasonal adaptations such as aestivation, migrations, different forms of seasonal polyphenism or polymorphism (e.g., seasonal changes of body color), etc. Many stink bugs demonstrate geographic clines of voltinism, producing several generations in the subtropical regions (environmentally controlled multivoltine development) and two or only one generation(s) polewards (environmentally controlled bi- or univoltinism). However, some species demonstrate a strictly bivoltine seasonal cycle: they always produce two annual generations, each with either winter or summer diapause. An example is Nezara antennata which produces two generations and enters facultative winter and summer diapauses. Semivoltine seasonal cycles last more than one year. They are not very rare among insects and are known in true bugs, but have not yet been recorded among pentatomids. Examples of different seasonal cycles are described and discussed in detail. Further discussion is focused on the ecological importance of photoperiodic and thermal responses in cases of natural or artificial dispersal of pentatomids beyond their original ranges. The phytophagous Nezara viridula and the predatory Podisus maculiventris and Perillus bioculatus are used as examples. An attempt is made to compare the phylogeny of Pentatomidae and distribution of realized patterns of their seasonal development. However, it is concluded that reconstruction of phylogenetic relationships cannot yet provide a sufficient basis for prediction of realized seasonal cycles. It is suggested that the terms uni-, bi-, multi-, and semivoltinism should refer to populations rather than species, since the realized patterns of seasonal development often differ between the northern and southern populations of the same broadly distributed species.     

Dynamics and seasonal abundance of stink bugs (Heteroptera: Pentatomidae) in a cotton-soybean ecosystem

Two soybean varieties (early-maturing group V and late-maturing group VII) and two cotton varieties (conventional and transgenic (Bt) were grown in adjacent replicated large field plots (approximately 0.1 ha each) at two locations for 3 yr. The dynamics and relative abundance of phytophagous stink bugs within these two crops were observed. The most abundant pentatomid species in both crops for all 3 yr were Nezara viridula (L.), Acrosternum hilare (Say), and Euschistus servus (Say). Several other species also were commonly collected. This is the first record of Mormidea lugens (F.) on soybean and E. quadrator Rolston, E. obscurus (Palisot), Holcostethus limbolarius (St?l), and Oebalus pugnax (F.) on cotton. Stink bugs began arriving in soybean when plant growth stages ranged from pod formation to full seed development. Peak numbers of these insects were found in soybean from the time of full-size seeds in the pods until early maturity. The bugs were first attracted to the earlier maturing cultivar (group V), where they remained until plants began to mature (R7). The pentatomids then moved to the later-maturing cultivar (group VII) as it reached full pod to full seed. Stink bugs began arriving in cotton from the time of the earliest flowers until after the first bolls formed. Peak numbers in cotton occurred during the time when all stages of developing bolls were present. Stink bug numbers were much greater in soybean than in cotton over all three seasons. This preference for soybean over cotton indicates the potential use of soybean as a trap crop for attracting stink bugs away from cotton. Additionally, the coordinated use of early- and late-maturing soybean cultivars as a trap crop could minimize the area requiring insecticides, as well as the number of insecticide applications to cotton.     

The Effect of Seasonal Changes on Nezara viridula (L.) (Hemiptera: Pentatomidae) and Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae) in Hawaii

The effect of seasonal changes in temperature and photoperiod on the interaction of Nezara viridula (Hemiptera: Pentatomidae) and its egg parasitoid Trissolcus basalis (Hymenoptera: Scelionidae) was investigated in the laboratory. We found no evidence of reproductive diapause in N. viridula under simulated Hawaiian summer and winter conditions. Further, although “diapause” coloration was obtained in the laboratory, it was not correlated with reproductive status. Studies of the survival of T. basalis provided with honey under the same simulated conditions showed that under summer conditions, only 2.1% of the female and 13.5% of the male population were still alive by 60 days. When provided with N. viridula egg masses at 30 days, 79.4% of the eggs were parasitized in a 3-h period. Under winter conditions, 54.3, 28.3, and 14.5% of the females were alive at 30, 60, and 90 days after adult emergence. When provided with N. viridula egg masses at 30, 60, and 90 days for 3 h, 57.6, 32.8, and 47.1% of the eggs were successfully parasitized. These studies suggest the limiting factor in the interaction of T. basalis and N. viridula is not reproductive diapause, but instead the ability of T. basalis to survive summer conditions.     

Duration of feeding and superficial and in-depth damage to soybean seed by selected species of stink bugs (Heteroptera: Pentatomidae)

Laboratory studies were conducted to compare duration of feeding and superficial and in-depth damage to soybean (Glycine max) seeds by the Southern green stink bug, Nezara viridula (L.), the Neotropical brown stink bug, Euschistus heros (F.), the red-banded stink bug, Piezodorus guildinii (Westwood), and the green-belly stink bug, Dichelops melacanthus (Dallas). Results indicated that feeding time was significantly longer for N. viridula (≈ 133 min) compared to E. heros and D. melacanthus (≈ 70 min), but not different from P. guildinii (≈ 103 min). There was a positive correlation between feeding time and the resulting damage for E. heros, N. viridula and P. guildinii (R2 > 0.80, P < 0.0001), but not for D. melacanthus (R2 = 0.1011, P = 0.1493). The deepest seed damage (2.0 mm) was made by P. guildinii and the shallowest (0.5 mm) by D. melacanthus. The depth of the seed damage by E. heros and N. viridula (0.8, 1.2 mm, respectively) was intermediate in comparison to the other species studied. Feeding damage to the seed endosperm caused variable cell disruption and protein body dissolution, particularly when P. guildinii fed on seeds, suggesting that the deleterious action of salivary enzymes was greater for this bug compared to the others.     

六种蝽象的染色体研究（半翅目：蝽科）

研究了6种蝽象的核型和减数分裂行为。结果表明：6个种的染色体组成均为2n(♂)=14, 具有X-Y性别决定机制;减数分裂行为比较一致,但在中期-Ⅰ常染色体和性染色体的排列方式具有种的特异性,可为蝽科昆虫的形态分类及系统发育提供有用的证据。     

Behavioral and developmental effects of neem extracts on Clavigralla scutellaris (Hemiptera: Heteroptera: Coreidae) and its egg parasitoid, Gryon fulviventre (Hymenoptera: Scelionidae)

Extracts of neem, Azadirachta indica A. Juss, negatively affected feeding and development of Clavigralla scutellaris (Westwood), a coreid pest of pigeonpea, Cajanus cajan (L.) Millspaugh. Labial dabbing, pod wall penetration, and seed damage by fifth instars were significantly reduced on beans, Phaseolus vulgaris (L.), that had been dipped in aqueous, methanolic, or hexane extracts of neem seed kernel. When fourth instars were dipped directly into aqueous extract, developmental abnormalities of the wings occurred at all levels tested and fecundity dropped to zero at concentrations above 0.3125%. The LC50 value was 3.14% (220 ppm azadirachtin) at 8 d. The scelionid wasp Gryon fulviventre (Crawford) is an important natural enemy of Clavigralla spp.; egg mortality from this parasitoid ranged from 37 to 85% during the fall cropping season. Feeding by newly emerged wasps was dramatically reduced when honey was mixed with aqueous neem suspension, but 6-d survivorship of adults did not differ significantly from that of the control. Wasp oviposition behavior was altered slightly when coreid eggs were treated with neem: the period of antennation was significantly extended, but time for drilling, oviposition, and marking was unaffected. Neem-dipped eggs were accepted for oviposition and progeny emerged successfully from these treated eggs. Exposure of already parasitized eggs to neem did not interfere with progeny emergence, longevity, or sex ratio. Thus, neem extract and egg parasitoids seem to be compatible and promising control strategies for C. scutellaris. Our results suggest that use of neem against pod-sucking bugs will not interfere with natural control provided by G. fulviventre.     

Ratio-dependent parasitism with Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae) on egg rafts of Nezara viridula (Linnaeus) (Hemiptera: Pentatomidae): effect of experimental variables and compatibility of 'ratio' and 'Holling' models

Abstract Egg rafts of Nezara viridula were exposed to the parasitoid wasp Trissolcus basalis in experimental arenas to establish the relationship of the rates of attack and parasitism to various combinations of arena size, parasitoid density, host density and parasitoid-to-host ratio. Arena sizes were varied in the ratio 1:9:63, with the largest having a search area of 1.44 m². Parasitoid and host densities were varied over a 27-fold range. The parasitoid-to-host ratios used were 1:1, 3:1 and 6:1. Finding time was related to a constant factor (flight propensity), rather than to the difficulty of finding (density of hosts). Initial attack rates were therefore related only to parasitoid numbers (or density), even at the lower densities and ratios. Parasitism rates (a function of attack rate per host) were thus also strongly related to parasitoid to host ratio, regardless of densities used and arena sizes. Even reducing host density, while keeping time and parasitoid density constant, increased the parasitism rate. A ratio model for parasitism rate was therefore compatible with the data but the more explicit Holling 'disc' equation was also compatible because handling time was sufficiently large to make it sensitive to the ratio of parasitoids to hosts for the densities used. We conclude that the two models would predict different results if the density of host egg rafts was in a range below one per square metre.     

Evaluation of cold-stored eggs of Dolycoris baccarum (Hemiptera: Pentatomidae) for parasitization by Trissolcus nigripedius (Hymenoptera: Scelionidae)

Trissolcus nigripedius Nakagawa (Hymenoptera: Scelionidae) is an egg parasitoid of Dolycoris baccarum L. (Hemiptera: Pentatomidae), a polyphagous insect pest of many crops including soybean. As a method for mass-rearing to augment the parasitoid, cold storage of host eggs were evaluated in the laboratory. After 0 (control), 8, 20, 60, 90, and 120 days of refrigeration, host eggs were given to adult female T. nigripedius. Host acceptance behaviors of the parasitoid, categorized as drumming, oviposition, and marking, on the refrigerated eggs and biological attributes of offspring were assessed. Most of the attributes examined were affected by the refrigeration of host eggs. But host eggs could be refrigerated for up to two months without significant change in emergence rate and sex ratio and with 90% of parasitism. In addition, the second generation of the parasitoid was not negatively affected at all. However, frozen eggs of D. baccarum can not be used for rearing the parasitoid since parasitism rate decreased to 44% on host eggs frozen for 8 days. Refrigeration of D. baccarum eggs could be useful for mass-rearing and augmentation of T. nigripedius to control D. baccarum without reduction in the quality of parasitoid’s progeny. Furthermore, refrigerated eggs could be supplemented in the field to boost the population of T. nigripedius since immature D. baccarum can not hatch after 20 days of refrigeration.     

Immunoelectron microscopical detection of tubulins during spermiogenesis in phytophagous bugs (Hemiptera: Pentatomidae)

Summary

Ultrastructural and immunocytochemical studies were carried out in the tail region of spermatids and spermatozoa of the phytophagous bugs, Acrosternum aseadum and Euchistus heros. The axoneme presented a 9+9+2 microtubule pattern and bridges occurred between axonemal microtubules 1, 5, and mitochondrial derivatives. Two paracrystalline structures, embedded in an amorphous matrix, were observed in the mitochondrial derivatives. The axonemal microtubules contained alpha, acetylated and tyrosinated tubulin. Cytoplasmic microtubules contained alpha, beta and gamma tubulin. Moreover, the gamma tubulin was detected near the electron dense rod, an element associated with the centriole, suggesting that this structure may be a microtubule organizing center.