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.     

Hot water immersion for surface disinfestation of Maconellicoccus hirsutus (Homoptera: Pseudococcidae)

Mealybug Maconellicoccus hirsutus (Green) adults, nymphs, crawlers, and eggs were tested for their susceptibility to hot water immersion at 47, 48, and 49 degrees C. Eggs inside ovisacs were found most tolerant with prolonged survival compared with other stages at all temperatures. Ovisacs required an average of 1.38, 1.46, and 1.62 times longer treatment duration than adults, nymphs, and crawlers, respectively, for 99.9% predicted mortality at 47, 48, and 49 degrees C. Lethal time estimations were calculated from inverse predictions of regressions derived from logit-transformed data as well as those created using a kinetic model. LT 99.9 estimations were 47.0, 21.2, and 11.9 min at 47, 48, and 49 degrees C, respectively, by using regressions with logit transformations. The kinetic model predictions were 43.9, 19.6, and 11.1 min at 47, 48, and 49 degrees C, respectively. During the study no emergence from eggs inside ovisacs was found after treatments of 52, 24, and 14 min at 47, 48, and 49 degrees C, respectively. Results from this study provide efficacious temperature-time treatments.     

Irradiation of Maconellicoccus hirsutus (Homoptera: Pseudococcidae) for phytosanitation of agricultural commodities

Studies on the tolerance of pink hibiscus mealybug, Maconellicoccus hirsutus (Green), to ionizing irradiation were undertaken to determine the dose needed to disinfest commodities of this pest. Overall, radiotolerance of M. hirsutus was found to increase with maturity. Target doses of 50 Gy reduced eclosion of eggs to <50%, but doses as great as 750 Gy did not eliminate hatching during the study. At 100 Gy, M. hirsutus eggs, crawlers, and nymphs were controlled, because progeny were not produced despite crawlers and nymphs living for much longer periods than unexposed individuals. Fecundity of treated crawlers and nymphs was greatly impacted by treatment of 100 Gy; crawlers developing into adults produced no eggs, and 10 adults of 3,983 treated nymphs (0.25%) produced 309 eggs. Few adult females exposed as nymphs deposited eggs because male nymphs died during development, which left the females unfertilized. By comparison, 89% of female nymphs treated at 100 Gy and mated as adults with nonirradiated males produced a total of 1,447 eggs (19 eggs per female). Evidence from this study suggests M. hirsutus reproduces sexually, not parthenogenetically. Adults, the most resistant stage, exposed to target doses of 100 Gy produced eggs that were 1.2% viable, from which a small portion of individuals successfully completed development and produced progeny. A target dose of 250 Gy was sufficient to control adult M. hirsutus because, at that dose, none of the eggs produced by 3,093 irradiated adults eclosed. The minimum dose needed to ensure quarantine security is between 100 and 250 Gy.     

Immune response of the hibiscus mealybug, Maconellicoccus hirsutus Green (Homoptera: Pseudococcidae), to oviposition of the parasitoid Anagyrus kamali Moursi (Hymenoptera: Encyrtidae)

Anagyrus kamali Moursi has been recently introduced into the Caribbean as a biological agent against the hibiscus mealybug, Maconellicoccus hirsutus Green. This host has a cellular defense reaction that involves encapsulation and melanization of the endoparasitoid egg. The impact of this immune response on the parasitoid progeny was assessed, as well as the response of the parasitoid countermeasures to overcome it. Under laboratory conditions, significant differences in the immune response were found for different developmental stages of M. hirsutus. The intensity of the immune response varied between second instar, third instar and adult mealybugs. After 30 h, the level of encapsulation was the highest for eggs oviposited in adults: 58% of eggs were encapsulated, followed by third (32%) and second (4%) instars. Three days after oviposition 23, 44 and 86% of the parasitoid eggs oviposited, respectively, in adult, third and second instars were not encapsulated. The unencapsulated parasitoid eggs could hatch and continue their development. Adult mealybugs required 30 h to encapsulate 50% of the eggs, whereas in second and third instars, 50% level encapsulation was never reached. Superparasitism had a saturating effect on the immune system; reduced levels of encapsulation occurred when more than 10 eggs were oviposited in a single mealybug. Wasp larvae were never encapsulated by M. hirsutus.     

Life history of the mealybug, Maconellicoccus hirsutus (Hemiptera: Pseudococcidae), at constant temperatures

Important life history parameters of the mealybug, Maconellicoccus hirsutus (Green), were characterized on hibiscus (Hibiscus rosa-sinensis L.) cuttings at six constant temperatures between 15 and 35 degrees C. The development of M. hirsutus was the fastest at 27 degrees C, where the mealybugs completed development in approximately 29 d. The lower (T(min)) and upper (T(max)) developmental thresholds and the optimal developmental temperature (T(opt)) for the development of female mealybugs were estimated as 14.5, 35, and 29 degrees C, respectively. The thermal constant (K), which is the number of temperature-day or degree-day units required for development, of the females was 347 DD. The original distribution range prediction (based on T(min) = 17.5 degrees C and K = 300 DD) indicated that M. hirsutus could complete at least one generation in all of the continental United States. However, results of this study suggested that the distribution range of M. hirsutus may expand northward because of the lower T(min), and the predicted number of generations in a year may be lower because of the higher K required to complete each generation. The average cumulative survival rate of M. hirsutus at 25 and 27 degrees C was 72%, which was significantly higher than 51 and 62% at 20 and 30 degrees C, respectively. M. hirsutus reproduced sexually, with each mated female producing 260-300 eggs between 20 and 27 degrees C but only approximately 100 eggs at 30 degrees C. Female longevity was reduced from 28 d at 20 degrees C to 19-21 d at 25-30 degrees C. At 27 degrees C, the net reproductive rate (R(o)) was estimated at 165 female symbol/female symbol, the intrinsic rate of population increase (r(m)) was 0.119 (female symbol/female symbol/d), the generation time (T(G)) was 43 d, and the doubling time (DT) was 5.8 d. The life table statistics suggested that the currently released biological control agents, which have higher r(m) than M. hirsutus, will be able to complete more generations than the mealybug within the tested temperature range; thus, they are effective against M. hirsutus.     

Hot-water treatments for control of Planococcus ficus (Homoptera: Pseudococcidae) on dormant grape cuttings

Hot-water immersions were tested for control of mealybug Planococcus ficus (Signoret), on dormant grape cuttings used for nursery stock. A range of hot-water temperatures (47-58 degrees C) were evaluated at immersion periods of 2, 5, 10, or 20 min, by using a total of 353,720 mealybugs across all treatments. A 5-min immersion at 51 degrees C is effective in killing > 99% of P. ficus. At or above this immersion period and temperature, there was no difference in mealybug stage mortality. We evaluated a commercial operation, which used a 5-min immersion in each of three water tanks: preheating (30.0 +/- 3 degrees C), hot-water (52.8 +/- 0.3 degrees C), and cooling (23 +/- 3 degrees C). The commercial procedure provided 99.8-100% mealybug control in each of three separate trials.     

No-choice host range tests for Allotropa sp. near mecrida,a parasitoid of the pink hibiscus mealybug,Maconellicoccus hirsutus (Hemiptera: Pseudococcidae)

Host range studies of the parasitoid Allotropa sp. near mecrida (Walker) (Hymenoptera: Platygastridae) were conducted prior to applying for a permit to release it against the pink hibiscus mealybug, Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae), in southern California. Using M. hirsutus as a control, four mealybug species were tested as potential hosts. Allotropa sp. near mecrida did not successfully reproduce in any of the mealybug species tested, except for the target species, M. hirsutus. The parasitoid was found to host feed upon one of the non-target species within the confined test environment. Subsequently a USDA-APHIS importation and release permit was granted.     

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)     

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.     

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.     

Manna scale,Trabutina mannipara (Hemprich & Ehrenberg) (Homoptera: Coccoidea: Pseudococcidae)*

Abstract. The mealybug Trabutina mannipara (Hemprich & Ehrenberg, 1829) is described and illustrated, and a neotype female selected from topotypic material collected in the Sinai Peninsula. A lectotype female is designated for Trabutina palestina Bodenheimer (1927) which is shown to be a junior synonym of T.mannipara.     

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.     

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.     

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 .     

Hot water treatment and insecticidal coatings for disinfesting limes of mealybugs (Homoptera: Pseudococcidae)

Hot water immersion and insecticidal coatings were tested to determine if they could be used to disinfest Persian limes, Citrus latifolia Tanaka, of the mealybug pests Planococcus citri Risso and Pseudococcus odermatti Miller & Williams. A 20-min 49 degrees C hot water immersion treatment is effective in killing mealybugs and all other arthropods tested found externally on limes, or under the calyx. No insects or mites were found to survive after the 20-min hot water treatment. In this test, 7,200 limes were treated with 1,308 insects killed and zero survivors. Treatment at 49 degrees C for 20 min did not significantly affect quality when treated fruit were compared with untreated control fruit. Four coatings were tested at a 3% rate: two petroleum-based oils (Ampol and Sunspray oil), a vegetable oil (natural oil), and a soap (Mpede). The coatings gave up to 94% kill (Ampol) of mealybugs, which is not sufficient to provide quarantine security. The coatings might be effective as a postharvest dip before shipment.     

Hybridization and sex pheromone responses in two closely related mealybug species (Homoptera: Pseudococcidae)

Abstract. Reciprocal crosses were made between the closely related species Planococcus citri and Planococcus ficus by using mating inducers. The pheromone responses of the hybrid offspring were bioassayed. The sex ratio of the offspring showed a striking shift in favour of females in comparison with homospecific matings mainly because of high mortality of male nymphs during the first instar. Hybrid males gave positive reactions only to pheromone extracts from the maternal species and showed no response to extracts from the paternal species. This result may be explained by the lecanoid chromosome system known for mealybug males, in which the paternal set of chromosomes becomes heterochro-matic (condensed and genetically inactive) starting from early embryogeny. Further evidence is, however, presented that (at least in certain tissues) the paternal set reverts to the euchromatic state and to genetical activity.     

Identification of Planococcus citri (Homoptera: Pseudococcidae) and the description of a new species

Planococcus pacificus sp.n. is described from the South Pacific, Australia and South East Asia. P.citricus is synonymized with P.citri. A key and illustrations are given to separate the species discussed from each other and from the similar P.ficus group.     

Impact of Gyranusoidea tebygi Noyes (Hymenoptera: Encyrtidae) on the Mango Mealybug Rastrococcus invadens Williams (Homoptera: Pseudococcidae) in Nigeria

This study investigated the impact of released exotic mango mealybug parasitoid Gyranusoidea tebygi on mango mealybug Rastrococcus invadens in Nigeria. Observations were also made on the occurrence of the mealybug on other host plants in the surveyed areas. The monitoring exercise started in 1991 about 2 years after the first release in Ibadan. By 1997 and 1998, G. tebygi was found to have crossed all agro-ecological barriers to colonize the entire area of infestation nationwide on mango as well as other host plants. During this period, the populations of R. invadens had greatly decreased from between 11.0 and 98.0 mealybugs per leaf in 1991 to between 0.0 and 18.2 mealybugs per leaf in 1998. This fall was attributed to the activities of the released parasitoid. At many sampling sites in 1998, mealybugs were virtually absent on both mango and other host plants. Predators that were observed during the survey, were the coccinellids: Exochomus promptus Weise, Chilocorus nigritus (F) and Nephus spp. Larvae of chrysopid species, Ceratochrysa autica (Walker) and Plesiochrysa sp. The hyperparasitoids reared from mummies were Marietta leopardina Motsch (Aphelinidae), Chartocerus hyalipennis Hayat and Chartocerus subaeneus (Forster) (Signiphoridea).