Planococcus Kraunhiae Research Articles

Identification of a receptor for the sex pheromone of the vine mealybug, Planococcus ficus

The vine mealybug, Planococcus ficus, is a significant pest of vineyards in all major grape growing regions of the world. This pest causes significant aesthetic damage to berry clusters through its feeding behavior and secretion of "honeydew", which leads to significant decreases in crop marketability. More importantly, the vine mealybug is a vector of several grapevine viruses which are the causal agent of grapevine leafroll disease, one of the most destructive and economically devastating diseases of the grape industry worldwide. As there is no cure for grapevine leafroll disease, the only control measures available to reduce its spread are to remove infected vines whilst simultaneously controlling mealybug populations. Using transcriptomic libraries prepared from male and female mealybugs and a draft genome, we identified and evaluated expression levels of members of the odorant receptor gene family. Interestingly, of the 50 odorant receptors identified from these P. ficus genetic resources, only 23 were found to be expressed in females, suggesting this flightless life stage has a decreased reliance on the olfactory system. In contrast, 46 odorant receptors were found to be expressed in the alate male life stage. Heterologous expression of eight of these receptors, along with the obligate co-receptor, Orco, in HEK293 cells allowed for the identification of two receptors that respond to lavandulyl senecioate, the sole constituent of the sex pheromone used by this species. Interestingly, one of these receptors, PficOR8, also responded to the sex pheromone used by the Japanese mealybug, Planococcus kraunhiae. The data presented here represent the first report of odorant receptor gene family expression levels, as well as the identification of the first sex pheromone receptor, in soft-scale insects. The identification of a receptor for the vine mealybug sex pheromone will allow for the development of novel, species-specific pest control tools and monitoring devices.

Sex-specific expression profiles of ecdysteroid biosynthesis and ecdysone response genes in extreme sexual dimorphism of the mealybug Planococcus kraunhiae(Kuwana).

Insect molting hormone (ecdysteroids) and juvenile hormone regulate molting and metamorphic events in a variety of insect species. Mealybugs undergo sexually dimorphic metamorphosis: males develop into winged adults through non-feeding, pupa-like stages called prepupa and pupa, while females emerge as neotenic wingless adults. We previously demonstrated, in the Japanese mealybug Planococcus kraunhiae (Kuwana), that the juvenile hormone titer is higher in males than in females at the end of the juvenile stage, which suggests that juvenile hormone may regulate male-specific adult morphogenesis. Here, we examined the involvement of ecdysteroids in sexually dimorphic metamorphosis. To estimate ecdysteroid titers, quantitative RT-PCR analyses of four Halloween genes encoding for cytochrome P450 monooxygenases in ecdysteroid biosynthesis, i.e., spook, disembodied, shadow and shade, were performed. Overall, their expression levels peaked before each nymphal molt. Transcript levels of spook, disembodied and shadow, genes that catalyze the steps in ecdysteroid biosynthesis in the prothoracic gland, were higher in males from the middle of the second nymphal instar to adult emergence. In contrast, the expression of shade, which was reported to be involved in the conversion of ecdysone into 20-hydroxyecdysone in peripheral tissues, was similar between males and females. These results suggest that ecdysteroid biosynthesis in the prothoracic gland is more active in males than in females, although the final conversion into 20-hydroxyecdysone occurs at similar levels in both sexes. Moreover, expression profiles of ecdysone response genes, ecdysone receptor and ecdysone-induced protein 75B, were also analyzed. Based on these expression profiles, we propose that the changes in ecdysteroid titer differ between males and females, and that high ecdysteroid titer is essential for directing male adult development.

Influence of mating disruption method aginst <i>Planococcus kraunhiae</i> on the parasitism by its parasitoid wasp <i>Anagyrus fujikona</i>.

Influence of mating disruption method aginst <i>Planococcus kraunhiae</i> on the parasitism by its parasitoid wasp <i>Anagyrus fujikona</i>.

Development and reproduction of the parasitic wasp Allotropa subclavata (Hymenoptera: Platygastridae) on the Japanese mealybug Planococcus kraunhiae (Hemiptera: Pseudococcidae)

Allotropa subclavata Muesebeck (Hymenoptera: Platygasteridae) is one of the most effective natural enemies of the Japanese mealybug Planococcus kraunhiae (Kuwana) (Hemiptera: Pseudococcidae), a serious pest in Japanese orchards. We examined the developmental and reproductive traits including host deprivation effect on oviposition of A. subclavata to evaluate its potential as a biological control agent for P. kraunhiae. The developmental zero and effective accumulative temperature of A. subclavata females and males reared on second-instar nymphs, a suitable host stage for this parasitoid, were 12.3 °C and 514.3 degree days and 12.8 °C and 432.8 degree days, respectively. The longevity of A. subclavata maintained with honey was longer than that of those maintained with water or no feeding. The average numbers of mature eggs in ovaries of the 0- and 30-day-old A. subclavata females were 301.1 and 290.4, respectively, and were not significantly different. Offspring production of 30-day-old A. subclavata females was approximately 80% that of 0-day-old female parasitoids. On average, 50% of all eggs were laid within 24 h of the start of oviposition. The intrinsic rate of increase at 25 °C was 0.115, which is considered to be approximate to that of the host, P. kraunhiae.

Seasonal occurrence and host range of the predatory gall midge Diadiplosis hirticornis (Diptera: Cecidomyiidae), a native natural enemy of Planococcus kraunhiae (Hemiptera: Pseudococcidae)

Diadiplosis hirticornis Felt (Diptera: Cecidomyiidae) larvae feed on the eggs of mealybugs and are potentially useful biological control agents against the Japanese mealybug Planococcus kraunhiae Kuwana (Hemiptera: Pseudococcidae). However, a detailed life history and their wild hosts remain unclear preventing effective use of this gall midge in orchards. We surveyed the seasonal occurrence and natural hosts of D. hirticornis in Saga, Northern Kyushu, Japan. Based on field surveys using pumpkin traps baited with P. kraunhiae, two peaks were detected in the annual adult emergence of D. hirticornis in both 2015 and 2016. Therefore, this gall midge appears to have at least two generations a year. In this study, D. hirticornis was observed to feed on at least three species of Pseudococcidae, including the important pests P. kraunhiae and Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), in the field. However, D. hirticornis was not found on Icerya purchasi Maskell (Hemiptera: Margarodidae) collected from a neighboring site of P. kraunhiae colonies. These results suggest that the host range of D. hirticornis is restricted to only Pseudococcidae.

The effects of mating disruption in two-year continuous treatment on Japanese mealybug, <i>Planococcus kraunhiae</i> (Hemiptera: Pseudococcidae), density and fruit damage.

The effects of mating disruption in two-year continuous treatment on Japanese mealybug, <i>Planococcus kraunhiae</i> (Hemiptera: Pseudococcidae), density and fruit damage.

Suppression of population growth of the Japanese mealybug, Planococcus kraunhiae (Hemiptera: Pseudococcidae), by using an attractant for indigenous parasitoids in persimmon orchards

We previously reported that two parasitic wasps, Anagyrus sawadai Ishii and Leptomastix dactylopii Howard, are strongly attracted to (2,4,4-trimethyl-2-cyclohexenyl)methyl butyrate (cyclolavandulyl butyrate, CLB), a cyclization product of the sex pheromone of the Japanese mealybug, Planococcus kraunhiae (Kuwana). These wasps attacked more P. kraunhiae in the presence of CLB in our field experiments. In the present study, we showed that these CLB-attracted wasps parasitized and suppressed the mealybug population increase in field persimmon orchards, which would lead to reducing mealybug damage on commercial products. Although many attractants for natural enemies are reported, compounds such as CLB that suppress pest population growth in fields are scarce. Moreover, to the best of our knowledge, this is currently the only example to demonstrate that the “non-natural” enemy that does not typically attack the pest under natural conditions can be enrolled in biological control by using its attractant.

Differential Juvenile Hormone Variations in Scale Insect Extreme Sexual Dimorphism.

Scale insects have evolved extreme sexual dimorphism, as demonstrated by sedentary juvenile-like females and ephemeral winged males. This dimorphism is established during the post-embryonic development; however, the underlying regulatory mechanisms have not yet been examined. We herein assessed the role of juvenile hormone (JH) on the diverging developmental pathways occurring in the male and female Japanese mealybug Planococcus kraunhiae (Kuwana). We provide, for the first time, detailed gene expression profiles related to JH signaling in scale insects. Prior to adult emergence, the transcript levels of JH acid O-methyltransferase, encoding a rate-limiting enzyme in JH biosynthesis, were higher in males than in females, suggesting that JH levels are higher in males. Furthermore, male quiescent pupal-like stages were associated with higher transcript levels of the JH receptor gene, Methoprene-tolerant and its co-activator taiman, as well as the JH early-response genes, Krüppel homolog 1 and broad. The exposure of male juveniles to an ectopic JH mimic prolonged the expression of Krüppel homolog 1 and broad, and delayed adult emergence by producing a supernumeral pupal stage. We propose that male wing development is first induced by up-regulated JH signaling compared to female expression pattern, but a decrease at the end of the prepupal stage is necessary for adult emergence, as evidenced by the JH mimic treatments. Furthermore, wing development seems linked to JH titers as JHM treatments on the pupal stage led to wing deformation. The female pedomorphic appearance was not reflected by the maintenance of high levels of JH. The results in this study suggest that differential variations in JH signaling may be responsible for sex-specific and radically different modes of metamorphosis.

Mealybug mating disruption by a sex pheromone derived from lavender essential oil

A characteristic constituent of lavender essential oils, lavandulol (2-isopropenyl-5-methyl-4-hexen-1-ol), and its relatives have been frequently discovered in the pheromones of mealybugs. Synthetic pheromones to interfere with their mate-finding communication are a potential management tool for these pests. The sex pheromone of the Japanese mealybug (Planococcus kraunhiae) is 2-isopropyliden-5-methyl-4-hexen-1-yl butyrate (isolavandulyl butyrate), and its alcohol moiety can easily be synthesized from lavandulol by means of acid-promoted double-bond migration. In this study, we synthesized isolavandulyl butyrate from natural lavandulol without isolating it from lavender essential oil. The resulting oil included both the pheromone and insect repellants, and the oil’s attractiveness was inferior to that of pure synthetic pheromone. However, the lavender oil-derived pheromone displayed a copulation-interference performance equivalent to that of the pure pheromone when large amounts were released around mealybug colonies. This study proposes a unique strategy for mealybug management using the pheromone derived from lavender essential oil.

フジコナカイガラムシの捕食寄生蜂フジコナカイガラクロバチの寄主齢選好性

We examined host stage preference of Allotropa subclavata, the most effective natural enemy of Planococcus kraunhiae, one of the serious fruit pests in Japan. Though adult females of A. subclavata drummed on all stages of the host, wasps could effectively insert the ovipositor against first and second instar nymphs. The next generation adults emerged from the hosts only when the wasps parasitized their first and second instar nymphs.

性フェロモンと有効積算温度を利用したカキのフジコナカイガラムシ（カメムシ目：コナカイガラ科）幼虫の発生時期予測

We investigated the possibility of predicting the emergence of first-generation young nymphs of the mealybug Planococcus kraunhiae (Kuwana) by using effective cumulative temperature, with peak sex pheromone trap captures as a base point. Seasonal yearly fluctuations in the number of sex pheromone trap captures in four persimmon fields in Japan (Shimane, Hiroshima, Gifu, and Fukuoka prefectures) indicated that Japanese mealybugs produce three to four generations in a year. The event of the first pheromone trap captures of wild mealybugs in the present study matched with those in our previous rearing experiments in Shimane Prefecture in 2007 and 2008 using male overwintering-generation nymphs raised in a ventilated case with a meteorological gauge (Stevenson screen). The actual timing of the first-generation nymph capture using band traps matched the estimated emergence time of the first-generation nymphs, which was calculated from the cumulative effective temperature starting from the pheromone trap capture time for the over-wintering adult male bugs. Therefore, setting pheromone trap capturing peak as a base point, prediction of occurrence of first-generation mealybug nymphs is considered possible, utilizing the effective cumulative temperature for persimmon.

단감수출단지 과원과 수출단감 병해충 조사

Between 2010 and 2012, diseases and insect pests of sweet persimmon were surveyed at sweet persimmon export complexes and non-export orchards in Suncheon, Jeonnam Province; Jinju, Changwon (Dongeup and Bukmyeon), and Gimhae, Gyeongnam Province; and Ulzu, Ulsan. The following diseases were found in the sweet persimmon orchards: angular leaf spot (Cercospora kaki), anthracnose (Colletotrichum gloeosporioides and Colletotrichum acutatum), circular leaf spot (Mycosphaerella nawae), powdery mildew (Phyllactinia kakicola), and gray mold (Botrytis cinerea). Circular leaf spot was the most frequent and serious disease, and C. gloeosporioides and C. acutatum were found on fruits. Thirty-three insect pest species that belonged to 32 genera of 20 families in 5 orders were found in the sweet persimmon orchards; the two-spotted spider mite, Tetranychus urticae, was also found in the surveyed orchards. Apolygus spinolae, Pseudaulacaspis cockerelli, and Adoxophyes orana were widely found in the surveyed orchards; Spodoptera litura and Homona magnanima were also recorded. Damage by insect pests was low, and the quarantine insect pests peach pyralid moth (Dichocrocis punctiferalis) and persimmon fruit moth (Stathmopoda masinissa) were rarely or not found in the sweet persimmon export complexes. In addition, other quarantine insect pests, such as persimmon false spider mite (Tenuipalpus zhizhilashviliae) and Japanese mealybug (Planococcus kraunhiae), were not detected. These quarantine insect pests were also not found in the sorting places, storage houses, and fruits for export; however, scale insects and two-spotted spider mites were found at a low rate. Although anthracnose (C. acutatum) infested fruit was found in the storage houses, only one in Jinju and Gimhae.

A convenient route for synthesis of 2-isopropyliden-5-methyl-4-hexen-1-yl butyrate, the sex pheromone of Planococcus kraunhiae (Hemiptera: Pseudococcidae), by use of β,γ to α,β double-bond migration in an unsaturated aldehyde

The Japanese mealybug Planococcus kraunhiae (Kuwana) is an important pest which spoils many kinds of fruit in Japan. Because conventional application of insecticides is often ineffective, alternative strategies are being investigated for management of this pest. Recent studies revealed that a pheromone-based technique which interferes with sexual communication, i.e. mating disruption, was promising. However, mating disruption usually requires a substantial amount of a pheromone. I therefore developed a new and convenient route for synthesis of the P. kraunhiae pheromone, 2-isopropyliden-5-methyl-4-hexen-1-yl butyrate (fujikonyl butyrate). First, a commercially available isomer of fujikonol, 2-isopropenyl-5-methyl-4-hexen-1-ol (lavandulol), was oxidized, furnishing the corresponding aldehyde (lavandulal). The β,γ double bond of lavandulal smoothly migrated to the α,β position in the presence of acids, and as a consequence, the corresponding aldehyde of fujikonol (fujikonal) was obtained. Fujikonal was then reduced to fujikonol, which was esterified with butyric acid to give the pheromone of P. kraunhiae. All the reactions were accomplished under very mild conditions (room temperature to 50 °C) with good yields. Moreover, only small amounts of by-products were generated. The synthetic pheromone obtained by this method can be used as a mating disruptant.

A new approach for mealybug management: recruiting an indigenous, but ‘non‐natural’ enemy for biological control using an attractant

AbstractWe previously discovered that (2,4,4‐trimethyl‐2‐cyclohexenyl)‐methyl butyrate (cyclolavandulyl butyrate, CLB) is an attractant for the mealybug‐parasitic wasp Anagyrus sawadai Ishii (Hymenoptera: Encyrtidae: Anagyrini). This wasp is not likely to parasitize the Japanese mealybug, Planococcus kraunhiae (Kuwana) (Hemiptera: Pseudococcidae), under natural conditions. In this study, we showed that this ‘non‐natural’ enemy wasp can parasitize P. kraunhiae in the presence of CLB in field experiments. Laboratory‐reared mealybugs placed on persimmon trees with CLB‐impregnated rubber septa were parasitized significantly more often by endoparasitic wasps than those on non‐treatment trees (18.1–40.3 vs. 0–6.3%). Anagyrus sawadai accounted for 20% of the wasps that emerged from mealybugs placed on CLB‐treated trees. Moreover, CLB attracted another minor parasitoid, Leptomastix dactylopii Howard (Hymenoptera: Encyrtidae: Anagyrini), which also parasitized more P. kraunhiae in the presence of CLB. All wasps that emerged from the mealybugs on control trees were Anagyrus fujikona Tachikawa, a major parasitoid of P. kraunhiae around the test location. These results demonstrated that CLB can recruit an indigenous, but ‘non‐natural’ enemy that does not typically attack P. kraunhiae under natural conditions, as well as a minor natural enemy, for biological control of this mealybug species.

Endocrocin and Its Derivatives from the Japanese MealybugPlanococcus kraunhiae

The Japanese mealybug, Planococcus kraunhiae, is suitable as a model insect for biosynthetic studies on mealybug pigments. Four yellow pigments, including two novel ones, were isolated from the mealybug bodies and characterized as endocrocin, a dicarboxylic acid named fujikonaic acid (1), emodin 1-O-β-D-glucopyranoside and 7-hydroxyemodin 1-O-β-D-glucopyranoside (2). The enzymatic activity of emodin 1-O-glucosyltransferase was observed in the extracts of insect bodies.

Molecular Identification of Mealybugs (Hemiptera: Pseudococcidae) Found on Korean Pears

Mealybugs are under a strict regulation at foreign trades of agricultural products because they are one of the most economically damaging groups of insects on food crops and ornamental plants. However, the absence of morphological characteristics enabling the discrimination of early life stages often cause a significant delay or rejection of a shipment when infested fruit is discovered, causing significant economic loss. A polymerase chain reaction-based method for species identification was developed for six mealybug species known to infest Korean pears including two regulated insects, Planococcus kraunhiae (Kuwana) and Crisicoccus matsumotoi (Siraiwa). Six sets of species-specific primers were designed based on the sequence comparison of the internal transcribed spacer 1 and 2 regions. Efficiency tests against 29 mealybug samples showed that this method could effectively discriminate different mealybug species regardless of their developmental stages. Blind tests against 11 field collected mealybug nymph samples indicated that a single polymerase chain reaction is enough to discriminate unidentified mealybugs collected on Korean pears. This new method will facilitate trade and export requirements, as well as identify the species at any stage of mealybug intercepted.

フジコナカイガラムシPlanococcus kraunhiae（Kuwana）（カメムシ目：コナカイガラムシ科）に対する性フェロモン成分による交信攪乱効果

We demonstrated that a synthetic sex pheromone, 2-isopropyliden-5-methyl-4-hexen-1-yl butyrate, disrupted the mating of the Japanese mealybug Planococcus kraunhiae (Kuwana) (Hemiptera: Pseudococcidae). The synthetic pheromone was impregnated into grey rubber septa. In the presence of the synthetic pheromone, the copulation rates of reared P. kraunhiae were significantly decreased in a plastic case (diameter: 8 cm, height: 6 cm), an insect net cage (each side: 95 cm), and a small scale orchard (9 m2). In Japanese persimmon orchards (4~5 a), the dispersion of high concentrations of the synthetic sex pheromone disturbed male orientation, leading them towards the pheromone traps, and consequently reduced the number of females that copulated. In the persimmon orchard, mating disruption based on the synthetic pheromone successfully controlled the population density of P. kraunhiae in the next generation.

フジコナカイガラムシの土着天敵Ｄｉａｄｉｐｌｏｓｉｓ ｈｉｒｔｉｃｏｒｎｉｓ（ハエ目：タマバエ科）の発育ゼロ点と有効積算温度，羽化時刻

In southwestern Japan, the Japanese mealybug Planococcus kraunhiae (Kuwana) (Hemiptera: Pseudococcidae) is one of the most serious pests that attack the Japanese persimmon Diospyros kaki Thunb. (Ebenaceae). Diadiplosis hirticornis (Felt) (Diptera: Cecidomiidae) is thought to be an important natural enemy of P. kraunhiae. In order to establish control measures that use D. hirticornis to control the population of the mealybug, we need fundamental information on the ecological and behavioral characteristics of D. hirticornis. As the first step, we investigated its developmental velocity at 17.5, 20, 22.5, 25, 27.5, 30, and 32.5°C and its hourly adult emergence pattern. The lower developmental threshold was found to be 11.1°C for both male and female individuals. For the whole stages from egg to adult, the day-degrees above the developmental threshold was 232.6 for male and 238.1 for female individuals. D. hirticornis was confirmed to be diurnal. A majority of the males emerged between 6 : 00 and 12 : 00, while most females emerged between 8 : 00 and 18 : 00.

Prediction of the hatch timing of the mealy bug Planococcus kraunhiae (Hemiptera: Pseudococcidae) in persimmon orchards using the effective accumulated temperature calculation simulation of the JPP-NET in Aichi

Prediction of the hatch timing of the mealy bug Planococcus kraunhiae (Hemiptera: Pseudococcidae) in persimmon orchards using the effective accumulated temperature calculation simulation of the JPP-NET in Aichi

Identification of a sex pheromone component of the Japanese mealybug, Planococcus kraunhiae (Kuwana)

A sex pheromone component of the Japanese mealybug, Planococcus kraunhiae, was isolated and identified. A crude extract of the pheromone obtained by airborne collection was first fractionated with Florisil column chromatography. The activity of each fractionated sample was examined in Petri dishes. The active fraction was further purified by HPLC and an active component was isolated by preparative GC. The purified compound showed attraction activity to adult males of P. kraunhiae in the field. The chemical structure was determined to be 2-isopropyliden-5-methyl-4-hexen-1-yl butyrate by GC-MS and NMR analyses.