Brown Soft Scale Research Articles

OUTCOMES OF PHYTOSANITARY MONITORING IN THE CITRUS PLANTATIONS OF ADJARA-GURIA

Phytosanitary monitoring conducted in 2023 across citrus plantations in the Adjara-Guria region in Georgia indicated an unfavorable situation. The damage caused by mites was particularly severe, with the citrus rusty (silver) mite (Phyllocoptruta oleivorus Ashm.) and the citrus red mite (Panonychus citri McGregor) observed at the highest intensity (3 points). Both old and younger plants were found to be infested by these pests. A widespread distribution of scale insects was also recorded, including the citrus rust mite (P. oleivorus Ashm.), citrus red mite (P. citri McGregor), yellow scale (Aonidiella citrina Coq.), citrus mussel scale (Lepidella beckii Newman), Japanese maple scale (Lopholeucaspis japonica Cockerell), tortoise wax scale (Ceroplastes japonicus Green), wax scale (Ceroplastes sinensis Del Guercio), brown soft scale (Coccus hesperidum L.), cottony camellia scale (Pulvinaria floccifera Westwood), citrus cottony scale (Pulvinaria aurantii Cockerell), citrus whitefly (Dialeurodes citri Ashm.), citrus blackfly (Aleurocanthus woglumi Ashby), woolly whitefly (Aleurothrixus floccosus Maskell), and citrus spiny whitefly (Aleurocanthus spiniferus Quaintance). The citrus blackfly, citrus spiny whitefly, and woolly whitefly were identified as particularly problematic. In Georgia, they are registered as quarantine pests.. KEYWORDS :Citrus, Mites, Monitoring, Pest, Scale insects

Population Size and Territories of Wilkins' Finches Nesospiza wilkinsi on Nightingale Island, Tristan da Cunha

Nesospiza finches are endemic to two small islands in the Tristan da Cunha Archipelago in the South Atlantic Ocean. The finches have radiated into two ecologically distinct forms at both islands: an abundant, small-billed dietary generalist, and a scarce, large-billed specialist. On Nightingale Island (area 2.6 km2), the endangered large-billed Wilkins' Finches N. wilkinsi use their strong bills to crack open the hard, nut-like fruits of Island Cape Myrtle Phylica arborea trees to access the seeds. Although Phylica fruits are available year-round, the finch population is constrained by the limited area of fruit bearing Phylica trees (c. 12 ha), which makes Wilkins' Finch one of the world's naturally rarest bird species. Prior to this study, rough estimates ranged from 30–85 pairs, but there has been no dedicated survey of the population size. Over the austral summers of 2012, 2016 and 2017 we systematically caught and colour ringed birds to better estimate the population size. Pairs were present wherever there are Phylica trees across the island, utilising even small, isolated Phylica copses. Mean territory size for 117 pairs in 2017 was 0.215 ± 0.094 ha (±SD, range 0.043–0.718) with a mean density of 9.8 pairs/ha in Phylica woodland. The total population was estimated to be 120 breeding pairs (c. 280–300 mature birds). The most pressing threat to the Wilkins' Finch population is the recent arrival of an invasive insect, the Brown Soft Scale Coccus hesperidum, and its associated sooty mould Seiridium phylicae, which reduces Phylica fruit loads and kills large trees. The potential use of a biological agent to control Brown Soft Scale infestations is being investigated, since without swift and effective mitigation, we predict the health of these woodlands will rapidly degrade with serious implications for the persistence of Wilkins' Finch. Until effective mitigation is taken, we recommend up-listing the species to Critically Endangered based on IUCN Red List Criterion B2.

Severe impact of introduced scale insects on Island Trees threatens endemic finches at the Tristan da Cunha archipelago

Inaccessible and Nightingale Islands are uninhabited islands in the Tristan da Cunha archipelago, central South Atlantic Ocean. Over the past decade, the spread and impacts of two species of invasive scale insects have increased steadily, severely affecting the Island Tree Phylica arborea woodlands and the endemic large-billed finches Nesospiza spp., which feed extensively on Phylica fruit. The first species, Greedy Scale Hemiberlesia rapax, causes local canopy diebacks and slightly reduced fruit loads. On Inaccessible, it appears to be only locally distributed, but on Nightingale it has spread rapidly since 2012 and now infects 95% of the Island Trees. The second species, Brown Soft Scale Coccus hesperidum and its associated sooty mould Seiridium phylicae, has expanded its range at Inaccessible since 2011, and colonised Nightingale by 2016. At Inaccessible, repeat transects between 2011 and 2018 show that Phylica fruit loads are markedly reduced and many large trees have died. Numbers of male Dunn's Finches N. acunhae dunnei, which rely on Phylica fruits, have declined by 50% in the last decade in heavily infested woodlands at Inaccessible Island, and some males in the most badly affected woodland are paired with small-billed Finches N. a. acunhae. If the trees on Nightingale follow a similar fate, the persistence of the endemic Wilkins' Finch N. wilkinsi will be under severe threat. The potential use of a biological agent to control C. hesperidium infestations should be investigated, since without swift and effective mitigation, we predict the health of these woodlands will degrade rapidly.

An Early Bioinvasion in the Azores. Global Circulation and Local Dynamics (1840s–1860s) in Response to the Brown Soft-Scale Coccus hesperidum

Bioinvasions occurred in the past as they do in the present, raising a set of ecological, economic, cultural and scientific changes. This paper focuses on how people dealt with and overcame the introduction and spread of the brown soft scale (Coccus hesperidum) in the Azorean orange groves in the 1840s–1860s. It describes the difficulties in the detection and the identification of the causal agent, the underestimation of the impacts in the early moments, the slow response and the limitations on methods of control. This is the earliest historical case of a plant pest documented in the Azores archipelago and the first that led to regulations concerning preventive measures and control. Research results are discussed in the framework of the global transfer of living organisms, rethinking Crosby’s original model of “Europeanizing” the colonial and overseas territories in the context of the nineteenth century empires. They highlight the relevance of understanding local dynamics, which reconsider the relationship between the center and the periphery.

Citrus Pest Quick Guide: Brown Soft Scale

A one-page quick guide written by Lauren M. Diepenbrock and Jamie D. Burrow and published by the Entomology and Nematology Department presents the life cycle of brown soft scale and provides several photos of the pest and the damage it causes to assist in identification. https://edis.ifas.ufl.edu/in1252

Praga e poder: história do “devorista das laranjeiras” (Açores, Portugal, 1840-1860)

The “orange tree devourer” (Coccus hesperidum, also known as the “Brown Soft Scale”) was the agent of a crisis with economic and political implications that affected orange production in the Azores between 1840 and 1860. This article analyzes the origin, expansion, and impact of the pest, and how island and central powers intervened very quickly to protect populations against pests and diseases in the context of Portuguese liberalism. There are differences between the responses in the three districts comprising the archipelago. The narrative addresses the historiography of epidemics in the first half of the nineteenth century, suggesting the influence of public health ideas on the genesis of nineteenth century phytopathological policies, of which his case is a pioneer.

Determination of suitable host plant for rearing of <i>Coccus hesperidum</i> (Homoptera: Coccidae)

Brown soft scale, Coccus hesperidum Linnaues (Homoptera: Coccidae) is an economically important pest on wide range of horticultural and agricultural crops. A study was carried out to determine the suitability of three host plants, black nightshade (Solanum nigrum), mandarin (Citrus reticulata) and cotton (Gossypium barbadense), for mass rearing of C. hesperidum under laboratory conditions of 25±2 °C, 65±5% RH and photoperiod of 14D:10L. C. hesperidum was able to develop and reproduce on all three host plants. However, according to developmental period, longevity and fecundity, mandarin was the best among the three host plants.

New report of insect pests and their natural enemies in pomegranate

Different insect pests and their natural enemies got identified and reported for the first time in pomegranate. Among the borer pests, shot hole borer (Xylosandrus compactus) and hairy caterpillars (Olene mendosa, Somena scintillans and Euproctis fraterna) have been reported for the first time in pomegranate. Gummosis has also been reported for the first time in pomegranate on 5 to 10 per cent plant from orchards in Solapur and Sangli districts of Maharashtra. A new species of shot hole borer, X. compactus was suspected to be associated with gummosis for which, confirmatory tests could be carried out to find out its role for its effective control. Among sucking pests, vine mealybug, Planococcus ficus, Cottony cushion scale, Icerya aegyptiaca, and Brown soft scale, Coccus hesperidium are first report on pomegranate from Maharashtra.

Pestiferous scale insects on native epiphytic orchids in south Florida: a new threat posed by exotic species

Abstract Scale insects belong to the superfamily Coccoidea, which includes serious plant pests such as soft scales, armored scales, and mealybugs. In 2009, in a natural habitat surrounded by urban development in Naples, FL, pestiferous scale insects (Coccidae) and mealybugs (Pseudococcidae) were discovered on inflorescences of Dendrophylax lindenii (Ghost Orchid). The next year, a follow-up survey was initiated to also include plants in two orchid-rich habitats within the Florida Panther National Wildlife Refuge. There, exotic scales were found on six different epiphytic orchid taxa. Of the scales encountered, Coccus hesperidum (Brown Soft Scale) and Diaspis boisduvalii (Boisduval Scale) are both well-known and serious pests of cultivated plants. Of particular concern is the possibility that these invasive insects have thoroughly infiltrated isolated, natural habitats of rare native orchids.

The strain HEB01 of Fusarium sp., a new pathogen that infects brown soft scale

The objectives of the present study were to identify a fungal strain, HEB01, isolated from naturally infected brown soft scale, Coccus hesperidum L. (Hemiptera: Coccidae), and to determine whether it is an entomopathogenic fungus. Fungal culture, reinoculation test, morphological observations, and infection behaviors were investigated. Additionally, the fungal gene sequence of translation elongation factor 1-a (EF-1a) was obtained for molecular identification. The results showed that the fungal strain HEB01 belongs to the Fusarium incarnatum-equiseti species complex and is part of the family Nectriaceae (Hypocreales: Sordariomycetes). The inoculation test and observations of infection behaviors indicated that strain HEB01 is a pathogenic fungus and confirmed that it infects brown soft scale. Thus, the HEB01 strain of Fusarium incarnatum-equiseti is the first pathogen in the genus Fusarium to be isolated from a brown soft scale.

Pestiferous Scale Insects on Native Epiphytic Orchids in South Florida: A New Threat Posed by Introduced Species

Scale insects belong to the superfamily Coccoidea, which includes serious plant pests such as soft scales, armored scales, and mealybugs. In 2009, in a natural habitat surrounded by urban development in Naples, FL, pestiferous scale insects (Coccidae) and mealybugs (Pseudococcidae) were discovered on inflorescences of Dendrophylax lindenii (Ghost Orchid). The next year, a follow-up survey was initiated to also include plants in two orchid-rich habitats within the Florida Panther National Wildlife Refuge. There, exotic scales were found on six different epiphytic orchid taxa. Of the scales encountered, Coccus hesperidum (Brown Soft Scale) and Diaspis boisduvalii (Boisduval Scale) are both well-known and serious pests of cultivated plants. Of particular concern is the possibility that these invasive insects have thoroughly infiltrated isolated, natural habitats of rare native orchids.

New Records of Mealybugs, Scale Insects, and Whiteflies (Hemiptera: Sternorrhyncha) from Mali and Senegal

This study documents new distribution records of Sternorrhyncha (Hemiptera) in Mali and Senegal. The mealybugs (Pseudococcidae) found were Ferrisia virgata Cockerell (striped mealybug), Phenacoccus manihoti Matile-Ferrero (cassava mealybug), and Phenacoccus solenopsis Tinsley (solenopsis mealybug). Also recorded was a giant mealybug, Icerya sp. (Monophlebidae), that was not identified to species. The soft scales (Coccidae) collected were Ceroplastes rusci (L.) (fig wax scale), Coccus hesperidum L. (brown soft scale), and Parasaissetia nigra (Nietner) (nigra scale). The armored scales (Diaspididae) collected were Aonidiella orientalis (Newstead) (oriental scale), Lepidosaphes tapleyi Williams (guava long scale), and Parlatoria crypta McKenzie (mango white scale). The whiteflies (Aleyrodidae) found were Aleurolobus marlatti (Quaintance) (Marlatt whitefly), Aleurotrachelus atratus Hempel (palm-infesting whitefly), and Trialeurodes ricini (Misra) (castor bean whitefly).

Differences in the sugar composition of the honeydew of polyphagous brown soft scale Coccus hesperidum (Hemiptera: Sternorrhyncha: Coccoidea) feeding on various host plants

Plant chemical composition is an important determinant of host plant-insect interactions. For many insects sugars are the main factors determining the acceptability of a plant. This study investigated changes in plant chemical composition and differences in sugar composition of different host plants induced by the feeding of Coccus hesperidum L. (Hemiptera: Sternorrhyncha: Coccoidea). Present in plant extracts and honeydew there were three monosaccharide sugars: glucose, fructose and arabinose, and one disaccharide - sucrose. Arabinose was only found in extracts of Ficus benjamina plants. The sugar content of the honeydew was greater than in the extracts of control plants and lower than that in the extracts of infested plants. The honeydew collected from C. hesperidum feeding on the three plant species differed significantly in sugar content. Extracts of coccid infested plants of the three species used in this study contained more sugar than the un-infested control plants. The results show that honeydew composition of scale insects differ and the differences reflect the chemical composition of the host plants.

Biology and behavior of Metaphycus angustifrons Compere (Hymenoptera: Encyrtidae), a newly discovered parasitoid of soft scale insects (Hemiptera: Coccidae) in California

Metaphycus angustifrons Compere has recently been found to be the most abundant parasitoid of brown soft scale, Coccus hesperidum L., in southern California. In laboratory experiments we examined several biological parameters of this species. M. angustifrons both oviposits and host feeds in brown soft scale and is a facultatively gregarious endoparasitoid of this soft scale insect. In contrast with other Metaphycus spp., M. angustifrons is a koinobiont parasitoid, allowing its host to grow up to 40% beyond its size at parasitism. Despite its high abundance on brown soft scale in the field, in the laboratory, high rates of parasitoid egg encapsulation are observed; about half of parasitized hosts failed to issue parasitoids. Furthermore, host scales that encapsulated parasitoids eggs showed significant reduction in development. Increased scale size at oviposition influences the size of emerging females but not the size of males. Female M. angustifrons are synovigenic. They emerge from their hosts without mature eggs and begin maturing eggs after they are provided a carbohydrate source. Carbohydrates prolong the life span of both female and male M. angustifrons. The size of female wasps influences egg load but not longevity. Finally, based on laboratory observations, M. angustifrons uses citricola scale almost exclusively for host feeding and not for oviposition. These results suggest that the role of this species in citricola scale’s decline in southern California in the 1950s–1960s was negligible.

Ultrastructural and cytochemical characterization of brown soft scale Coccus hesperidum (Hemiptera: Coccidae) infected by the Lecanicillium lecanii (Ascomycota: Hypocreales)

The ultrastructural and cytochemical characterization of the brown soft scale, Coccus hesperidum L. (Hemiptera: Coccidae) infected by the hyphomycete Lecanicillium lecanii (Zimmermann) Gams & Zare, belonging to the phylum Ascomycota and order Hypocreales, was investigated by light, scanning and transmission electron microscopy. Gold cytochemistry was used to label chitin in the cuticle of the scale insect. The results revealed that the pathogenic fungus, L. lecanii generally infected by penetrating the integument, especially at anus, vulva, spiracles, stigmatic furrow, body margin, and the areas of cuticle with grooves, fissures and rugoses areas. The conidia became attached to the host body surface and germinated into hyphae that established colonies by branching repeatedly. Hyphae penetrated the integument by means of their penetration pegs using mechanical force and extracellular enzymes. During integument penetration, the hyphae extended vertically or parallel along the cuticle. Labeling with the WGA/Ovo-G complex showed disruption of the parallel sheets of chitin and a decrease in the density of the gold particles surrounding the penetrated hyphae. Hyphal invasion also separated the cuticle and epidermis from each other. Once in the haemocoele, blastospores of the fungus infected the haemocytes and internal organs. After some time, the nutritive value of the haemocoele decreased and the insect's internal organs disappeared. The hyphae then produced conidiophores and released them through the cuticle of the scale insect cadaver.

Sequences of sex allocation and mortality in clutches of Metaphycus parasitoids of soft scale insects and the prevalence of all‐female broods

Abstract.1. In many gregarious or quasi‐gregarious parasitoids that experience local mate competition, precise sex ratios with low variance are observed. Precise sex ratios can be achieved by laying male and female eggs in non‐random sequences.2. Developmental mortality can also alter sex ratios of emerging offspring, and subsequently influence sex ratio optima.3. The present study investigates sex allocation by Metaphycus flavus Howard, M. luteolus Timberlake, and M. angustifrons Compere (Hymenoptera: Encyrtidae), endoparasitoids of soft scale insects, in the laboratory.4. All three Metaphycus species had precise secondary sex ratios when parasitising brown soft scale, Coccus hesperidum, L. in the laboratory. Moreover, we documented that all three species lay fertilised (= female) eggs first followed by unfertilised (= male) eggs at the end of the oviposition bout. However, there were significant differences in sex allocation sequences among species.5. Mortality rates of eggs allocated within an oviposition bout also varied considerably, indicating that there is a significant interspecific variation in sequence position‐specific mortality.6. Using a stochastic Monte Carlo simulation approach, we provide evidence that the incidence of all‐female broods in these parasitoid wasps appears mainly due to developmental mortality and not due to decisions by the ovipositing female. In two species the prevalence of all‐female broods was independent of clutch size, contrary to what is expected from theory. The influence of mortality on optimal sex allocation in these parasitoids is discussed.

Cellular immune response of brown soft scale Coccus hesperidum L. (Hemiptera: Coccidae) to eggs of Metaphycus luteolus Timberlake (Hymenoptera: Encyrtidae)

The parasitic wasp, Metaphycus luteolus Timberlake, is an endoparasitoid of various soft scale insects including brown soft scale, Coccus hesperidum L. Development of this parasitoid in scale hosts is hindered by encapsulation. In the present study, using transmission and scanning electron microscopy, we show that hemocytes are responsible for encapsulation, which is mediated by the direct deposition of cells and melanin on the surface of M. luteolus eggs. By 12 h post-oviposition, scale hemocytes, presumably granulocytes, aggregate, spread and directly lyse on the surface of parasitoid eggs. This process continues for at least 1 day and results in the gradual formation of a capsule. Two to three days post-oviposition, a melanized capsule is well formed and signs of chemical deposition are evident by examination of the outer surface of the capsule. These results demonstrate that soft scale insects are fully capable of melanotic encapsulation of foreign material mediated by hemocytes.

Precise sex ratios manifested by several encyrtid parasitoids (Hymenoptera: Encyrtidae) of brown soft scale, Coccus hesperidum L. (Hemiptera: Coccidae)

We examined whether several facultatively gregarious encyrtid (Hymenoptera: Encyrtidae) endoparasitoids of brown soft scale, Coccus hesperidum L., manifest precise sex allocation under field conditions. Metaphycus luteolus (Timberlake), Metaphycus angustifrons (Compere), Metaphycus stanleyi (Compere), and Microterys nietneri (Motshulsky) evince brood sex ratios that are female-biased and extremely precise (low variance in the number of sons per host). Typically, this sex allocation pattern is attributed to extreme local mate competition (LMC) in which only one foundress exploits a patch of hosts and mating occurs mostly between her offspring. However, such a pattern of sex allocation was not detected for Metaphycus helvolus (Compere). Also, a large proportion of the broods in all five species contained only daughters; thus, an excess of male-only broods was expected if unmated females (i.e., females that can produce only sons) contribute offspring before mating. All-male broods were rare in our samples. This finding coupled with the life history characteristics of these wasps, such as the exploitation of aggregated hosts and the long life span and mobility of males, suggest that nonlocal mating is frequent. Our empirical work suggests that it is advantageous to allocate precise sex ratios in cases in which mating opportunities for males are not restricted to their natal host and/or when multiple foundresses exploit large patches of hosts. Limited theoretical work also supports this prediction but more detailed studies of this taxon’s mating structure and other life history characteristics are necessary to understand their sex allocation decisions.

Survey of brown soft scale Coccus hesperidum L. parasitoids in southern California citrus

The parasitoid complex of brown soft scale, Coccus hesperidum L., a multivoltine soft scale, was determined in southern California citrus over the period February 2004–March 2006. The survey was conducted by placing brown soft scale-infested yucca leaves in the canopy of citrus trees and subsequently rearing individually isolated parasitized scales in the laboratory. A total of 14 species parasitized brown soft scale in the field, the most abundant ones belonging to the genus Metaphycus Mercet (75%). The most abundant parasitoid species was Metaphycus angustifrons Compere (38% parasitism), and this is a new record of establishment for this species in California. Coccophagus species accounted for only 11% parasitism. There were important spatio-temporal differences across the parasitoid complex survey locations. We also found that the five most abundant encyrtid parasitoid species showed preferences for scales of different sizes. Our results have implications for biological control of citricola scale, Coccus pseudomagnoliarum (Kuwana), an important pest of citrus in the San Joaquin Valley of central California. Notably, this species is nearly absent in southern California. Brown soft scale is considered to be an alternate host for parasitoids of citricola scale, a univoltine soft scale, at times when the latter species is unavailable for parasitism.

Responses of Metaphycussp. nr. flavus to semiochemicals released from a scale host, Coccus hesperidum

Metaphycus sp. nr. flavus (Encyrtidae: Hymenoptera) is a parasitoid species collected from the Mediterranean region which lays its eggs in the immature stages of several economically important soft scale insects (Hemiptera: Coccidae), including brown soft scale, Coccus hesperidum L. (= host insect). Preliminary tests suggested that the parasitoid is most successful in producing offspring when it oviposits in the younger stages of brown soft scale. In Y-olfactometer bioassays measuring wasp choices and residence times, naive parasitoids were significantly more attracted to yucca leaves infested with 26, 27, or 28 d-old scale than to uninfested leaves, whereas leaves with older (29-30 d-old) scale were no more attractive than uninfested leaves. Parasitoids also spent significantly more time in the arm with yucca leaves infested with 26 d-old scale than in the arm with uninfested leaves. These results are consistent with observations of the parasitoid’s reproductive success on scale of different ages, whereby older scale are more likely to encapsulate the developing eggs of M. sp. nr. flavusfemales than are younger scale. Further bioassays determined that yucca leaves that had been infested with 26 d-old scale but from which the scale had been removed were as attractive as infested leaves. In contrast, infested yucca leaves from which scale had been removed and the leaves subsequently washed with distilled water were less attractive than infested leaves. Furthermore, the wash water containing scale residues was attractive to female wasps. In total, these results suggest that Metaphycussp. nr. flavus females utilize volatile, water soluble compounds produced by brown soft scale as cues to locate suitable hosts.