Mealybug Pest Research Articles

The effect of four botanical volatile oil against aphid (Aphis gossypii) and mealybug pests (Phenacoccus solenopsis). A toxicological and chemical composition study

Given the economic damage caused by cotton mealybugs Phenacoccus solenopsis, (P. solenopsis) and aphids Aphis gossypii (A. gossypii), it was a need to look for more acceptable and safe materials. Four local plant extracts were assessed Ocimum basilicum, Origanum majorana, Pipper nigrum, and Schinus terebinthifolius represented by their volatile oils, against these two pests in the laboratory, with the following LC50 values for each applied volatile oil extract against aphid and mealybug 1938.05, 7391.33, 674.81, 5548.65, 644.45, 4383.52, 727.88, and 6735.62 ppm using the four previous extracts respectively. The highest mortality percentage was 50.0 and 49.3% for pipper nigrum, while the lowest percentage was for O. basilicum with 36.2 and 31.2% against P. solenopsis and A. gossypii, respectively. The oils that gave the highest mortality percentages pipper nigrum and Origanum majorana were analyzed using GCMS technique revealed the existence of major compounds belonging to the terpenoids chemical group, which have a noticeable role in the process of controlling these pests.

Potential of Pangi Leaf Extract For Papaya Mealybug Control (Paracoccus marginatus)

The use of smer plant extracts is one alternative in environmentally friendly pest control. This research generally aims to obtain a technology for controlling Paracoccus marginatus mealybug pests that is environmentally friendly and easily applied by farmers. This study aims to determine the formulation of vegetable insecticide extract of pangi leaves to control papaya mealybug P. marginatus. This research was conducted at the Laboratory of Plant Pests and Diseases, Faculty of Agriculture, Sam Ratulangi University Manado. This research method used consisted of five treatments of pangi leaf extract dosage, namely: 5%, 10%, 20%, 40% and control. Each treatment was tested on pest nymphs. P. marginatus. And each treatment was repeated 5 times. The results of the study showed that 40% pangi leaf extract had the highest percentage of daily mortality at 24% and 48%. The higher the concentration of pangi leaf extract formulation, the higher the killing power on mealybug P. marginatus.

Coccinellid predators of mealybugs infesting banana in South India, including a new species and a new record of Scymnus Kugelann (Coleoptera: Coccinellidae), with notes on other natural enemies.

Several species of mealybugs infest various parts of bananas and plantains including foliage, fruits, rhizome and roots in all the major banana growing regions of India and cause moderate to occasionally serious damage but systematic attempts at documenting the mealybug pests of banana and their natural enemies are lacking in India. In this study, mealybugs infesting bananas and plantains in Tamil Nadu, South India, are documented along with their coccinellid predators and other natural enemies. The exotic Jack Beardsley mealybug, Pseudococcus jackbeardsleyi Gimpel & Miller, was found to be a major pest of banana bunches in all localities surveyed in Tamil Nadu and the grey pineapple mealybug, Dysmicoccus neobrevipes Beardsley, was a serious pest in some isolated pockets. Three coccinellids, Scymnus (Pullus) coccivora Ramakrishna Ayyar, Nephus regularis Sicard and Slipinskiscymnus saciformis (Motschulsky) were found to be the major predators of all species of mealybugs. Brumoides suturalis (Fabricius) was predatory on solenopsis mealybug (Phenacoccus solenopsis Tinsley) only and Hyperaspis maindroni Sicard was associated with solenopsis mealybug and pink pineapple mealybug (Dysmicoccus brevipes (Cockerell)). One new species, Scymnus (Pullus) spicatus sp. n., is described as a predator of Jack Beardsley mealybug and striped mealybug (Ferrisia virgata (Cockerell)). Scymnus (Pullus) syoitii Sasaji, 1971, a Japanese species, is recorded for the first time from India as a predator of banana root mealybugs in Tamil Nadu and on Planococcus citri (Risso) in Karnataka. Brief notes on the other natural enemies of banana mealybugs are also given with illustrations.

Habitat heterogeneity reduces abundance of invasive mealybugs in subtropical fruit crops

Abstract The simplification of agricultural landscapes has been associated with an increase in pest pressure. While monocultures increase the resources available for pests and may facilitate their dispersion, the lack of non‐crop habitats may reduce the resources available for pest natural enemies. Herein, we tested which of these hypotheses, namely ‘resource concentration’ and ‘natural enemies’, can better explain the abundance of invasive mealybug pests in two subtropical fruit crops. For this aim, 17 persimmon orchards and 16 citrus orchards were sampled during three different seasons across two consecutive years. Using a model selection approach, we assessed the effects of the surrounding landscape (proportion of focal crops and semi‐natural habitats at different distances) and inter‐row ground cover vegetation on the abundance of mealybugs and their natural enemies. The proportion of focal crop in the landscape increased the abundance of mealybugs attacking both crops. This effect was found at closer distances (up to ~600 m) in citrus and at both closer and further distances (up to 1250 m) in persimmon. Non‐crop habitats, both surrounding semi‐natural habitats and ground cover vegetation, decreased the abundance of mealybugs by increasing the activity of their parasitoids in persimmon. Conversely, non‐crop habitats did not decrease the abundance of the main mealybug species attacking citrus, likely because this mealybug species was not attacked by native or naturalized parasitoids. Synthesis and applications. Our models show that the increase in habitat heterogeneity at local and landscape scales can reduce the abundance of invasive mealybugs in subtropical crops via ‘resource concentration’ and ‘natural enemies’ mechanisms. Therefore, habitat diversification strategies should be considered in the conservation biological control of invasive mealybugs. Importantly, our findings also show that the presence of efficient natural enemies is critical to maximize their control through habitat diversification strategies.

Farmer perception, knowledge and management of the scale insect pest complex infesting crops and trees in Coastal Kenya

Scale insects and mealybugs (Hemiptera: Sternorrhyncha: Coccomorpha) are serious plant sap-sucking pests affecting a wide range of cultivated crops and tree species. The insects are highly diverse and can have devastating effects on yields due to lack of farmer awareness and inappropriate management practices. Recent alien mealybug invasions in Kenya include among others, papaya mealybug (Paracoccus marginatus), a highly invasive pest that is spreading quickly. Farmer experience with diverse crop pests can support development of a successful pest management strategy and contribute to reduced impacts on both crop yields and agro-biodiversity. This socio-economic survey was carried out in three coastal counties of Kenya (Mombasa, Kilifi and Kwale) to establish the impact of scale insect and mealybug pests on farmer livelihoods and to document the perception, knowledge and management practices used by smallholder farmers. Data from oral interviews using ODK were administered to respondents and analysed using Excel and GENSTAT. It emerged that 26% of the respondents were familiar with scale insects and 51% with mealybugs, respectively. Of these, 78.13 % and 94% acknowledged having encountered scale insects and mealybugs, respectively, on their farms. The farmers confirmed that scale insect pests affected a high diversity of crops and trees. About 56% of the respondents used pesticides to control the pests while 25% did not apply any management strategy. The remaining 19% practiced cultural control methods such as field sanitation and intercropping with less susceptible crops. Pesticides were reported to be moderately effective (41-70%) at controlling scale insects and mealybugs. Other management options reported by farmers included farm hygiene, the use of high-pressure water jets, and applications of ash and bio-pesticides such as home-made neem extract. Based on the findings, it is recommended that capacity building for farmers and input providers be undertaken to enhance the knowledge of scale insect and mealybug pest biology, symptoms of crop and tree attack, host ranges and management practices. Additonally, training on the use of low-risk pest control products and innovative control methods should be undertaken to reduce the impact of the pest on crop production and agro-biodiversity. Keywords: Farmer knowledge, management, mealybugs, scale insects and socio-economic survey.

Factor and Constraints Involved in Income Generation from Sericulture: A Study in three Districts of West Bengal, India

Sericulture is an important sector for income generation in rural areas. Socio-personal and management factors along with relevant constraints were identified for income generation from sericulture in West Bengal. A total of 127 respondents were taken under the three districts i.e., Murshidabad, Nadia and South 24 Parganas. Total 14 socio-personal and 7 management factors were taken as independent variables and were statistically analyzed to understand their relationship with dependent variable income (y). The statistic used was correlation coefficient (r). Only 7 from socio-personal and 5 from management variables were found positively correlated with income. A total of 14 and 3 constraints were identified against mulberry and cocoon production, respectively. For mulberry production, 7 constraints were pest and disease related in that root rot disease and mealy bug pest (tukra) effected 8.66% and 18.11% with 6th and 1st rank respectively. For cocoon production 2 constraints were solely disease related in that grasserie infection and muscardine infection effected 62.20% and 29.92% with 1st and 2nd rank respectively. In socio-personal and management categories, a total of 4 major constraints were identified against income generation. However, based on the findings, it is to be mentioned that for any future income generation policy in sericulture care should be taken on identified factors and constraints based on their importance identified in this study.

A Novel Insect Overwintering Strategy: The Case of Mealybugs.

Insects have limited ability to regulate their body temperature and have thus required a range of strategies to withstand thermally stressful environments. Under unfavorable winter conditions, insects often take refuge under the soil surface to survive. Here, the mealybug insect family was selected for the study. Field experiments were performed in fruit orchards in eastern Spain. We used specifically designed floor sampling methods combined with fruit tree canopy pheromone traps. We found that in temperate climates, the large majority of the mealybugs move from the tree canopy to the roots during the winter, where they turn into belowground root-feeding herbivores to survive and continue underground the reproductive process. Within the rhizosphere, mealybugs complete at least one generation before emerging on the soil surface. The preferred area to overwinter is within 1 m in diameter around the fruit tree trunk, where more than 12,000 mealybug flying males per square meter can emerge every spring. This overwintering pattern has not previously been reported for any other group of insects showing cold avoidance behavior. These findings have implications at the winter ecology level but also at the agronomical level since treatments to control mealybug pests are, until now, only based on the fruit trees' canopy.

Toxicity assessment of common acaricides and mineral oils on Anagyrus vladimiri, an effective biocontrol agent of citrus mealybug.

Chemical pesticides, while playing an important role in the suppression of insect pests, should be used in a manner that minimizes negative effects on natural enemies. The parasitoid, Anagyrus vladimiri Triapitsyn (Hymenoptera: Encyrtidae), plays an important role in the management of mealybug pests of citrus groves in the Mediterranean region. This study was conducted to evaluate the effect of commonly used acaricides (Spirodiclofen, Spirotetramat, Sulfur, Fenpyroximate, Abamectin) and mineral oils (Levanola, EOS, JMS, and Ultrapaz) on acute mortality of A. vladimiri. Toxicity was assessed in 4 cases: (i) direct spray application on adults, (ii) pesticide application on the mummified host, (iii) feeding with contaminated food, and (iv) contact with pesticide residue. The pesticide Abamectin, applied alone and with Levanola oil was highly toxic to adults in all bioassays, with the exception of direct spray application on the mummified host. Fenpyroximate was found to be highly toxic only when sprayed directly on adults, and sulfur was slightly harmful. Mineral oils were harmful when ingested with food; otherwise, they did not cause appreciable adult mortality. The findings of the present study suggest that all tested materials, with the exception of Abamectin and Fenpyroximate, are compatible with the survival of A. vladimiri. Direct ingestion of oils can, however, cause a degree of mortality. Given that indiscriminate use of these pesticides may affect the population ecology of A. vladimiri, they should be used with caution.

New Report of Oriental Mealybug Rhizoecus Amorphophalli Betrem (Hemiptera: Pseudococcidae) in Amorphophallus Muelleri Tubers in Indonesia

Since 2020 porang (Amorphophallus muelleri Blume) has been declared as an important commercial crop grown in Indonesia. Recently, porang tubers a coated of a distinct white waxy substance was observed at seed storage. The symptoms pose a threat to tuber vigour quality due to the intensive infestation on stored tubers. This sap- sucking insect sucks the juice leading to desiccation and shrivelling of tubers. This study aims to identify the sap- sucking insect pest attacks the storage porang tubers. The studies carried out at ILETRI. Identification of the caused insect species was done by observing symptoms visually, morphological identification of adult females using Compound microscope Olympus Bx43 in 40 X magnification, and tuber germination and growth of 250 infested tubers in the field. Regarding to the specific symptoms whose soft body coated of a distinct white waxy substance and morphological measurement of the average length of the adult females (862.62±46.3 μm with range between 764 - 904 μm), it’s supposed caused by mealybug in Rhizoecus amorphophalli (Hemiptera:Pseudococcidae). Our founding revealed that R. amorphophalli is first discovered as causal agent of a mealybug pest of porang in Indonesia and turned out to be very detrimental because their infestation caused 90 percent of infested porang tubers unable to germinate and grow.

EFEKTIVITAS INSEKTISIDA NABATI DALAM MENGENDALIKAN HAMA KUTU PUTIH (Paracoccus marginatus) PADA TANAMAN PEPAYA (Carica papaya L.)

Papaya (Carica papaya L.) cultivation gets a lot of disturbances such as pests or diseases that can reduce the quality and quantity of papaya fruit. The use of vegetable insecticides is effective in controlling pests and has potential as a plant insecticide such as citronella, neem and cloves. This study aims to determine daily mortality and obtain the most effective botanical insecticides in controlling mealybug pests on papaya plants. The study consisted of two stages: (1) assessing the percentage of daily mortality, (2) the effectiveness of citronella oil, neem extract and clove oil vegetable insecticides on papaya seedlings. Daily mortality data were calculated using the daily mortality formula and data on the effectiveness of vegetable insecticides were analyzed using analysis of variance. The results showed that the highest percentage of mortality by giving citronella oil had a 24-hour daily mortality percentage and clove oil at a 48-hour daily mortality percentage. Botanical insecticides had an effect on all observation parameters, plant height, number of leaves and stem diameter, while the most effective treatment in controlling the mealybug P. marginatus treatment N1 was citronella oil with a concentration of 1 cc/500 mL.

Insecticidal Activity of Essential Oils against Mealybug Pests (Hemiptera: Pseudococcidae): A Systematic Review and Meta-Analysis

Most mealybugs of the Pseudococcidae family are important pests of agriculture and ornamental gardens. Our aim was to perform a review and meta-analysis on 14 published scientific articles on the insecticidal activity of essential oils (EOs) against mealybug species of the Pseudococcidae family. Data on (1) species, genus, families, and plant parts from which the EO was extracted; (2) the main compounds of each EO; (3) the highest and lowest concentrations tested; and (4) the application method used for the toxicological studies was collected from each study. The metafor package (R software) was used to perform a three-level random effects meta-analysis. The families Lamiaceae, Rutaceae, Myrtaceae, Zingiberaceae and Euphorbiaceae and the genera Citrus, Cymbopogon, Syzygium, Cinnamomum and Jatropha were the most used among the studies. According to the results from the meta-analyses, 13 out of 24 genera analyzed were effective against mealybugs. All methods were effective, but fumigation and indirect contact were the most frequently used methodologies. The results obtained from the present review and meta-analysis could be used for the potential development of natural biopesticide formulations against mealybugs belonging to the Pseudococcidae family.

Effectiveness of Neem Seed Extract Formulation (Azadirachta Indica) and Bitung (Barringtonia asiatica) against Mealybug Papaya (Paracoccus marginatus) (Hemiptera: Pseudococcidae)

The papaya mealybug (Paracoccus marginatus) Williams & Granara de Wilink (Hemiptera: Pseudococcidae) is a main pest of papaya plants. Attacks by these pests can cause plants failed to produce the fruit and even to death. The usual control technique used by farmers is the use of synthetic pesticides that have a negative impact on human health and the environment. The alternative to control using botanical insecticides is a good solution to control the population of P. marginatus. The purpose of this study is to know the effect of neem seed oil formulation and bitung to know which treatments with concentrations are most effective in reducing the population density of papaya mealybug pests. The experiment took place in Rejasari Village, Langensari Subdistrict, Banjar City, West Java, from March 2021 to July 2021. Experiment using the Randomized Block Design consisted of ten treatments with three replications. The results were obtained that a formulation of bitung 3% could suppress the densities of papaya mealybug ( P. marginatus) populations at 65%. The average weight of the resulting papaya contained a 3% formulation of bitung found at 9.8 kg/tree. botanical pesticides of bitung oil 3% can be used instead of synthetic pesticides to control the population of P.marginatus.

Detectability of Hibiscus Mealybug, Nipaecoccus viridis (Hemiptera: Pseudoccocidae), DNA in the Mealybug Destroyer, Cryptolaemus montrouzieri (Coleoptera: Coccinellidae), and Survey of Its Predators in Florida Citrus Groves.

The Hibiscus mealybug, Nipaecoccus viridis (Newstead), has recently established in Florida citrus and become a pest of concern given secondary pest outbreaks associated with management of citrus greening disease. Chemical controls used to manage other citrus arthropod pests are not as effective against N. viridis due to its waxy secretions, clumping behavior, and induced cellular changes to host plant tissue which increase microhabitats. Populations of this mealybug pest are regulated by natural enemies in its native region, but it remains unclear if resident natural enemies in Florida citrus could similarly suppress N. viridis populations. This investigation: 1) established species-specific primers for N. viridis based on the mitochondrial gene Cytochrome-oxidase 1 (COI), 2) determined duration of N. viridis DNA detectability in a known predator, the mealybug destroyer (Cryptolaemus montrouzieri Mulsant), by using identified primers in molecular gut content analysis, and 3) screened field-collected predators for the presence of N. viridis DNA. The detection rate of N. viridis DNA was >50% at 36 h after adult C. montrouzieri feeding but DNA was no longer detectable by 72 h after feeding. Field-collected predators were largely comprised of spiders, lacewings, and C. montrouzieri. Spiders, beetles (primarily C. montrouzieri), and juvenile lacewings were the most abundant predators of N. viridis, with 17.8, 43.5, and 58.3 of field-collected samples testing positive for N. viridis DNA, respectively. Our results indicate that Florida citrus groves are hosts to abundant predators of N. viridis and encourage the incorporation of conservation or augmentative biological control for management of this pest.

Range of host plants, spatial distribution, and insect predator of Phenacoccus manihoti (Hemiptera: Pseudococcidae) as an emerging pest of cassava plants in Bali, Indonesia

Abstract. Supartha IW, Widaningsih D, Susila IW, Yudha IKW, Utama IWEK, Wiradana PA. 2022. Range of host plants, spatial distribution, and insect predator of Phenacoccus manihoti (Hemiptera: Pseudococcidae) as an emerging pest of cassava plants in Bali. Biodiversitas 23: 3022-3030. The cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae) is a very destructive pest in cassava farming in Indonesia. The insect has already made its way into Indonesia, where it has attacked cassava plants with indications of a bunchy top, which may cause plant death. The objectives of this study were to 1) discover and identify an invasive pest of cassava mealybug pest, P. manihoti, that attacks cassava plants in Bali; 2) map the distribution and abundance of these pest species populations on cassava plants in Bali; 3) describe the structure of the pest population in cassava plantations in Bali; 4) identify the dominant factors that influence the population structure of P. manihoti in Bali, and 5) evaluate the predator fauna in regulating the population. The findings revealed that the mealybug species that attacked cassava in Bali was P. manihoti, an exotic species that had never been published earlier. With a high population abundance, the pest has spread far and effectively overall in regencies/cities in Bali Province. In all regency/city regions, the population structure of P. manihoti was dominated by age groups of instar-1 and two nymphs, with the exception of the Buleleng Regency, which was dominated by age groups of nymphs instar 3 and 4. The nature of polyphagy and cosmopolite features that are readily adaptable to the environment and host plant variables, farming pattern, temperature and rainfall factors were the key factors impacting the population structure of P. manihoti in the field. Cryptolaemus montrouzieri, Chrysoperla carnea, and Scymnus sp. were discovered to have a role in managing P. manihoti populations in the field. The predator fauna community is structurally diverse, abundant, and has a low dominance. Cryptolaemus montrouzieri was the most dominant of the three producer species in the field. These results indicate that there is a positive potential shown by predatory mealybugs in the field and can be used as an initial model by related parties in formulating policies related to controlling insect pests of cassava plants.

Reproductive success and progeny sex ratio of a laboratory colony of Anagyrus fusciventris (Hymenoptera: Encyrtidae)

ABSTRACT Anagyrus fusciventris (Girault) is a parasitoid of both Pseudococcus calceolariae (Maskell) and P. longispinus (Targioni Tozzetti), two economically important mealybug pests in New Zealand. A male-biased sex ratio was often observed in a laboratory colony of A. fusciventris. We investigated the effect of mating status on female A. fusciventris longevity, fecundity, progeny sex ratio and the rate of parasitism achieved under controlled laboratory conditions. In addition, the impact of host body size on progeny sex ratio was investigated. The progeny sex ratio of unmated (virgin) females (VF) and two types of mated females (24hM: opportunities for mating limited to 24 h or LtM – lifetime opportunities for mating) was tested under similar conditions. Results indicated that females can be reproductively active within 24 h. On average, 24hM females produced 23% female offspring while LtM females produced 45% females, suggesting that multiple mating is required for a balanced sex ratio. VF produced only male offspring through arrhenotokous parthenogenesis. When reared at 23°C and 16 h photoperiod, VF, 24hM and LtM females lived for 25, 44, 51 days, and parasitised 46, 67 and 87 mealybugs respectively. The average lifetime reproductive output (total number of offspring emerged) of VF, 24hM and LtM females was 41, 58 and 75 offspring, respectively. Female-biased progeny emerged from larger hosts while male-biased progeny often emerged from smaller hosts. Implications of these results are discussed in relation to opportunities to improve the quality of a laboratory colony with a balanced progeny sex ratio.

Intraguild Interactions between the Mealybug Predators Cryptolaemus montrouzieri and Chrysoperla carnea.

Simple SummaryThe ladybird Cryptolaemus montrouzieri is a widely commercialized biological control agent of mealybugs. The green lacewing Chrysoperla carnea is mainly released for aphid control, but also attacks mealybugs. Both species have shown potential to control various economically important species of mealybug pests of greenhouse crops. As these predators may be simultaneously present in a crop, the risk of negative interactions between both predators was evaluated in this laboratory study. Individuals of different life stages of either predator were placed together in petri dish arenas and predation was recorded. Attacks between individuals of both species were frequently observed, with lacewing larvae being the dominant predators in most combinations. When mealybug nymphs or lepidopteran eggs were added to the arena, the incidence of attacks between the predators was greatly diminished. The relevance of these observations for the use of the predators in the biological control of greenhouse pests is discussed.The ladybird Cryptolaemus montrouzieri and the green lacewing Chrysoperla carnea have shown potential for use in augmentative biological control of mealybug pests in greenhouse crops. In the context of combining these predators within an integrated pest management system, the risk of negative intraguild interactions between both predators was evaluated in a laboratory setting. Different life stages of either predator were confronted in petri dish arenas containing a Ficus benjamina leaf, and after 24 h the incidence and direction of intraguild predation (IGP) was recorded for each combination. The effect of adding Planococcus citri nymphs or Ephestia kuehniella eggs as extraguild prey on the level of IGP was also studied. IGP was frequently observed between the two predator species and was asymmetrical in favour of C. carnea in most cases. The presence of extraguild prey reduced the number of IGP events between the predators to a similar extent. The relevance of the observed intraguild interactions for the combined use of these predators in protected cultivation is discussed.

POPULASI DAN TINGKAT SERANGAN HAMA KUTU PUTIH Dysmicoccus brevipes (Hemiptera : Pseudociccidae) PADA TANAMAN JAHE (Zingiber officinalle Rosc) DI DESA NUAMURI KECAMATAN KELIMUTU

This study aims to determine the population and level of attack of mealybug pests on ginger plants during harvesting in Nuamuri Village, Kelimutu District, Ende Regency. This research was carried out from February 2020 to July 2020, in Detubewa village, Nuamaro village and Nuamuri village. Observations were made by directly counting pests and damaged and attacked rhizomes, using the path method. Data analysis used is data obtained from the location of observations in tabulation based on the results of direct observations in the field. What was observed was the population and attack rate of each affected ginger planting location. The results showed that during the observation, the highest population of mealybugs was found in Detubewa village with 2,645 heads and the lowest value was in Nuamaro village, namely 2,127 heads, the highest pest population after Detubewa village was village Nuamuri with 2,478 individuals. Meanwhile, the attack rate and presentation of very heavy attacks were in Detubewa village by 84%, and heavy attacks in Nuamuri village at 66% and Nuamaro village at 68%.

Parasitoids (Hymenoptera) of Mealybug Pests (Hemiptera: Pseudococcidae) from Southern Brazil: Molecular and Morphological Characterization.

Parasitoids of three mealybug pests (Hemiptera: Pseudococcidae), Planococcus ficus (Signoret), Pseudococcus sociabilis Hambleton, and Pseudococcus viburni (Signoret) have been identified for the first time in Brazil. Mealybugs were collected in fruit-growing areas along southern Brazil during 2013-2016. An integrative approach, combining morphological and molecular methods, was used to identify the Brazilian parasitoids to the species level. Fifteen species were recorded, including 14 primary parasitoids belonging to Encyrtidae and Platygastridae and a single secondary parasitoid species belonging to Signiphoridae. The encyrtid parasitoids Acerophagus flavidulus (Brèthes), Anagyrus calyxtoi Noyes and Zaplatycerus sp., and the signiphorid secondary parasitoid Chartocerus axillaris De Santis are reported for the first time in Brazil.

Genomic insight into diet adaptation in the biological control agent Cryptolaemus montrouzieri

BackgroundThe ladybird beetle Cryptolaemus montrouzieri Mulsant, 1853 (Coleoptera, Coccinellidae) is used worldwide as a biological control agent. It is a predator of various mealybug pests, but it also feeds on alternative prey and can be reared on artificial diets. Relatively little is known about the underlying genetic adaptations of its feeding habits.ResultsWe report the first high-quality genome sequence for C. montrouzieri. We found that the gene families encoding chemosensors and digestive and detoxifying enzymes among others were significantly expanded or contracted in C. montrouzieri in comparison to published genomes of other beetles. Comparisons of diet-specific larval development, survival and transcriptome profiling demonstrated that differentially expressed genes on unnatural diets as compared to natural prey were enriched in pathways of nutrient metabolism, indicating that the lower performance on the tested diets was caused by nutritional deficiencies. Remarkably, the C. montrouzieri genome also showed a significant expansion in an immune effector gene family. Some of the immune effector genes were dramatically downregulated when larvae were fed unnatural diets.ConclusionWe suggest that the evolution of genes related to chemosensing, digestion, and detoxification but also immunity might be associated with diet adaptation of an insect predator. These findings help explain why this predatory ladybird has become a successful biological control agent and will enable the optimization of its mass rearing and use in biological control programs.

Evaluation of RNA Interference for Control of the Grape Mealybug Pseudococcus maritimus (Hemiptera: Pseudococcidae).

Simple SummaryRNA interference (RNAi) is a defense mechanism that protects insects from viruses by targeting and degrading RNA. This feature has been exploited to reduce the expression of endogenous RNA for determining functions of various genes and for killing insect pests by targeting genes that are vital for insect survival. When dsRNA matching perfectly to the target RNA is administered, the RNAi machinery dices the dsRNA into ~21 bp fragments (known as siRNAs) and one strand of siRNA is employed by the RNAi machinery to target and degrade the target RNA. In this study we used a cocktail of dsRNAs targeting grape mealybug’s aquaporin and sucrase genes to kill the insect. Aquaporins and sucrases are important genes enabling these insects to maintain water relations indispensable for survival and digest complex sugars in the diet of plant sap-feeding insects, including mealybugs. In our experiments, administration of dsRNA caused a reduction in expression of the target genes and an increase in insect mortality. These results provide support for the application of RNAi to control the grape mealybug.The grape mealybug Pseudococcus maritimus (Ehrhorn, 1900) (Hemiptera: Pseudococcidae) is a significant pest of grapevines (Vitis spp.) and a vector of disease-causing grape viruses, linked to its feeding on phloem sap. The management of this pest is constrained by the lack of naturally occurring resistance traits in Vitis. Here, we obtained proof of concept that RNA interference (RNAi) using double-stranded RNA (dsRNA) molecules against essential genes for phloem sap feeding can depress insect survival. The genes of interest code for an aquaporin (AQP) and a sucrase (SUC) that are required for osmoregulation in related phloem sap-feeding hemipteran insects (aphids and whiteflies). In parallel, we investigated the grape mealybug genes coding non-specific nucleases (NUC), which reduce RNAi efficacy by degrading administered dsRNA. Homologs of AQP and SUC with experimentally validated function in aphids, together with NUC, were identified in the published transcriptome of the citrus mealybug Planococcus citri by phylogenetic analysis, and sequences of the candidate genes were obtained for Ps. maritimus by PCR with degenerate primers. Using this first sequence information for Ps. maritimus, dsRNA was prepared and administered to the insects via an artificial diet. The treatment comprising dsRNA against AQP, SUC and NUC significantly increased insect mortality over three days, relative to dsRNA-free controls. The dsRNA constructs for AQP and NUC were predicted, from sequence analysis to have some activity against other mealybugs, but none of the three dsRNA constructs have predicted activity against aphids. This study provides the basis to develop in planta RNAi strategies against Ps. maritimus and other mealybug pests of grapevines.