An experimental study of morphological variation in mealybugs (Homoptera: Coccoidea: Pseudococcidae)

Abstract Cultures of a number of species of mealybug were reared under a variety of controlled environments and the effects of factors such as temperature, relative humidity and host plant on the morphology of the adult females examined. It was found that temperature had the greatest effect. The lengths of the appendages and setae, and the numbers of wax producing pores and ducts, vary over a wide range within a single species when specimens are reared at different temperatures. The relationship with temperature is generally linear, with size and pore numbers increasing with decreased temperature. However, some characters, noticeably the numbers of tubular ducts, reach their highest values at an intermediate temperature. It is suggested that while variation in size is a direct response to temperature, other characters are influenced by size or by a combination of size and environmental factors acting independently. Rearing mealybugs under different environmental conditions in order to induce morphological variation is shown to be a useful technique for resolving difficult species complexes.     

Taxonomy and nomenclature of five hitherto inadequately-known genera of mealybugs (Homoptera: Coccoidea: Pseudococcidae)

Abstract The type-species of four genera of Pseudococcidae are studied. Fonscolombia Lichtenstein is redefined, the type-species, Fonscolombia graminis Lichtenstein is assigned to the Pseudococcidae, redescribed and a lectotype designated. Laboulbenia Lichtenstein is accepted as an objective synonym of Antonina Signoret. Tetrura Lichtenstein ( non : Lesson) is accepted as an objective synonym of Coccura Sulc. The adult female of the material of this species which Lichtenstein misidentified as Tetrura rubi (Schrank) is redescribed and illustrated. Brevennia Goux is redefined, and the type-species Ripersia (Brevennia) tetrapora Goux redescribed. The characteristics of Asphodelococcus Morrison are discussed, the type-species Ripersia asphodeli Bodenheimer redescribed and a neotype designated; A.meoconcitae Tranfaglia & Marotta is a new synonym of A. asphodeli .     

Meiotic parthenogenesis and heterochromatization in a soft scale,pulvinaria hydrangeae (Coccoidea: Homoptera)

Summary Meiotic parthenogenesis of a type not previously described was found in Pulvinaria hydrangeae Steinweden. During diakinesis 8 bivalents were formed. At prometaphase the spindle was tripolar but anaphase I was bipolar and normal. After completion of division of the primary oocyte, the following sequence occurred: 1. polar body I divided, usually into 3 products; 2. the secondary oocyte divided to yield the egg pronucleus and polar body II; 3. the egg pronucleus divided into its two haploid products; and 4. the second polar body divided. The products of the egg pronucleus fused while dividing to restore the diploid chromosome number; this division may be equated to the first cleavage division. The products of the polar bodies did not take part in the formation of the embryo proper or the mycetocytes.Among the embryos produced by females of two out of the three populations studied some of the embryos showed a heterochromatic chromosome set, characteristic of males in this and related families. The reproductive system of the females as well as the eggs did not contain any sperm; thus the male embryos were apparently produced parthenogenetically.The euchromatic and heterochromatic chromosome sets were genetically identical, since they both originated from the egg pronucleus by mitosis. The heterochromatization of one set but not the other might be due in part to a previous difference in their position in the cytoplasm.The females were completely homozygous yet they produced male and female embryos. Thus it appears that sex determination in the group does not depend on the segregation of genetic factors in either males or females.In addition to male and female embryos, three types of degenerating embryos were observed. It is believed that these embryos were formed by polyploid somatic cells which invaded abnormal eggs and embryos and took over development.     

Diploid arrhenotoky and automictic thelytoky in soft scale insects (Lecaniidae: Coccoidea: Homoptera)

Parthenogenesis is reported in three soft scales with 2n=16. In the unfertilized eggs of all three, oogenesis is normal and diploidy is restored by the fusion of the division products of the haploid female pronucleus. In Lecanium putmani Phillips 12 of 13 uninseminated females collected in the wild produced only males. The 21 inseminated females produced 15% males. The males were diploid but contained one euchromatic (E) and one heterochromatic (H) chromosome set. Most of the eggs produced by the inseminated females contained sperm but a few did not. It was concluded, therefore, that females develop from fertilized eggs and males from unfertilized eggs and that the species was diploid arrhenotokous. In L. cerasifex Fitch only 18 of 56 females collected in the wild had been inseminated. The frequency of males among their embryos was 22%. The males were again diploid with one E and one H set of chromosomes. Among the 38 uninseminated females, 27 produced only males, and 10 produced only females. All the female producers contained needle-like bacterial symbionts. Most of the male producers, and most of the inseminated females contained no symbionts; the rest contained rod-like symbionts. It was concluded, therefore, that the females of L. cerasifex studied belonged to two races, a diploid arrhenotokous race and an obligate automictic thelytokous race. Eucalymantus tessellatus (Signoret) is obligate automictic thelytokous. All the females examined were uninseminated and produced only females.Supported by Grant GB 23665 from the National Science Foundation, Washington, D.C.     

美盾蚧属一新种记述（同翅目：蚧总科，盾蚧科）

本记述采自安徽黄山寄生于竹类上的美盾蚧属一新种。模式标本保存于安徽省黄山市林业局。     

Endomitosis in the mealy bug,Planococcus citri (Homoptera: Coccoidea)

Endomitosis in the Malpighian tubules of the mealy bug Planococcus citri (Risso) is described. The stages are identified on the basis of the length of the chromosomes and the distance between the sister chromatids or chromosomes. The appearance of the chromosomes in the various stages of endomitosis is compared to that in other hemipteran insects. During anaphase and telophase of endomitosis the ends of the sister chromatids and chromosomes tend to stay together longer than the other parts. It is suggested that in holokinetic chromosomes special regions for holding the chromatids together are concentrated near the ends of the chromosomes.Supported by grant GB1585 from the National Science Foundation, Washington, D.C.     

Evolution of chromosome number in mealybugs (Pseudococcidae: Homoptera)

Chromosome numbers of over 90 species of mealybugs are presented (71 for the first time). The diploid chromosome number (2n) ranged from 8 to 64, but over 68% of the species had 2n=10, and 10 is considered to represent the ancestral 2n in this family. Since only 4 species had 2n<10,and 26 had 2n>10, it is concluded that in this family increases in 2n occurred much more often than decreases. The data are compared to those from two other coccid families, the Diaspididae and the Eriococcidae. Unexpectedly, in both the Pseudococcidae and the Diaspididae the frequency of species with the modal 2n is lowest among species from monotypic genera and from genera from which only a single species was examined, and increases with the increase in the number of species examined per genus.(died June 10, 1977)     

Chromosome systems in the eriococcidae (Coccoidea Homoptera)

Spermatogenesis is described in two eriococcid species and the observations are compared to those previously reported. In Gossyparia spuria the diploid chromosome number is 28 in both males and females. In the female all the chromosomes are euchromatic. In most male tissues 14 of the chromosomes are euchromatic (E) and 14 are heterochromatic (H). Prior to the first meiotic division in males the number of H chromosomes was reduced. During prophase I all the cells showed 14 E chromosomes and from 1 to over 9 H chromosomes. The range of chromosome numbers in metaphase I was similar to that in prophase I. All the chromosomes divided in anaphase I, and, following differential uncoiling at interkinesis, the E and H groups of chromosomes segregated from each other at anaphase II. Only the E groups formed sperm. The presence of a variable number of H chromosomes and a haploid number of E chromosomes in spermatogenesis suggested the presence of the multiple-D variant of the Comstockiella chromosome system. In this system some of the H chromosomes become euchromatic prior to prophase I of spermatogenesis and pair with their E homologues. All the remaining H chromosomes are thus univalents, while among the E elements, some are univalents and the rest are bivalents. The observed reduction in the number of H chromosomes in the first meiotic division which was previously attributed to pairing among the H chromosomes, is now interpreted to be the result of the return of some of the H chromosomes to a euchromatic state and to their subsequent pairing with their E homologues. Spermatogenesis in Eriococcus araucariae was similar to that of G. spuria except that the reduction in the number of H chromosomes was not as extensive. The chromosome systems of the two species are compared to those of other eriococcids and the differences are briefly discussed.Supported by grant GB1585 from the National Science Foundation, Washington, D. C.     

The type-species of Lindingaspis MacGillivray (Homoptera: Coccoidea: Diaspididae)

Melanaspis samoana Lindinger the type-species of Lindingaspis is re-described and illustrated from syntype specimens and a lectotype is selected.     

Susceptibility of Maconellicoccus hirsutus (Homoptera: Pseudococcidae) to methyl bromide

Eggs, crawlers, early nymphs, late nymphs, and adults of the pink hibiscus mealybug, Maconellicoccus hirsutus (Green), were tested for their susceptibility to methyl bromide in 2-h laboratory fumigations at ambient conditions (25 degrees C, 95% RH). Dose-response tests indicated that the egg was the most susceptible life stage with an LC99 of 20.2 mg/liter. Based on probit analysis of dose-response data, no significant differences were observed among susceptibilities of the crawler, early stage or late stage nymphs, or adults at either the LC50 or LC99 level, but late stage nymphs were more tolerant than early stage nymphs in a separate paired comparison test. Confirmatory tests showed that a dose of 48 mg/liter methyl bromide, the USDA-Animal Plant Health Inspection Service treatment dose schedule for mealybugs at 21-26 degrees C, produced 100% mortality of all life stages. On the basis of these results, we conclude that the methyl bromide treatment schedule for mealybugs will provide quarantine security for M. hirsutus infesting commodities for export or import.     

Mealybugs of the Mirococcus Borchsenius, 1947 genus-group (Homoptera,Coccinea: Pseudococcidae)

The genus Mirococcus Borchsenius, 1947 is revised. Longicoccus Danzig, 1975 and Polystomophora Borchsenius, 1948 are considered new subjective synonyms of Mirococcus. Nine species, Mirococcus inermis (Hall, 1925) (= Polystomophora orientalis Matesova, 1960, syn. n.; = P. arakensis Moghaddam, 2010, syn. n.), M. ostiaplurimus (Kiritshenko, 1940), comb. n., M. sphaeroides Danzig, 1975, M. clarus Borchsenius, 1949 (= M. ashtarakensis Ter-Grigorian, 1964, syn. n.; = M. affinis Ter-Grigorian, 1967, syn. n.; = M. psammophilus Koteja, 1971, syn. n.) M. longiventris (Borchsenius, 1949), M. festucae Koteja, 1971, M. oligadenatus Danzig, 1982, M. ulykpani Danzig, 1990, and M. fossor Danzig, 1983 are taxonomically discussed and illustrated. Longicoccus cerariferus Danzig, 1975 and L. divnogoricus Gavrilov, 2003 are transferred to the genus Fonscolombia Lichtenstein, 1877; thus, the new combinations Fonscolombia cerarifera, comb. n. and F. divnogorica, comb. n. are formed.     

Serological studies on five species of Pseudococcidae (Homoptera)

Abstract. Populations of Planococcus cini, Planococcus ficus, Pseudococcus obscurus, Pseudococcus calceolanae and Pseudococcus longispinus were selected for immunoelectrophoretic tests from which correlation and distance coefficients were calculated. Cluster analysis of serological data allowed construction of a dendrogram in which the phylogenetic relationships among the five species are presented. The conclusions were found to be in agreement with modern views on taxonomic interrelations among the five species based on female and male morphology. The recent separation of Planococcus citn' and Planococcus ficus as independent species is emphasized.     

Generic vapor heat treatments to control Maconellicoccus hirsutus (Homoptera: Pseudococcidae)

Vapor heat treatments were developed against life stages of the mealybug Maconellicoccus hirsutus (Green) (Homoptera: Pseudococcidae). Treatments tested were 47 degrees C for 5-50 min in 5-min increments and 49 degrees C for 3, 5, 8, 10, and 12 min. All tests were conducted with mixed age M. hirsutus on Chinese pea, Pisum sativum L. Treatment at 47 degrees C required 45 min to kill all M. hirsutus, whereas treatment at 49 degrees C required 10 min. The adult female and nymphal stages were the most heat tolerant at 47 degrees C, but the egg stage was the most heat tolerant at 49 degrees C. Use of the vapor heat treatments on other commodities will require achieving or exceeding the proper temperature and duration at all locations on the host where M. hirsutus may reside.     

A new species of Dysmicoccus Ferris (Homoptera: Pseudococcidae) from India

Dysmicoccus williamsi sp.n. is described and illustrated. A key is provided for the indentification of Oriental species of Dysmicoccus Ferris.