Performance of the Striped Mealybug Ferrisia virgata Cockerell (Hemiptera: Pseudococcidae) under Variable Conditions of Temperature and Mating

Male nutritional status does not impact the reproductive potential of female Cnaphalocrocis medinalis moths under conditions of nutrient shortage

In addition to sperm, some accessory substances transferred to females during copulation act as nuptial gifts by passing on valuable nutrients in many insect species. The nutritional status of the males can thus have a great effect on the mating behavior, fecundity and even the longevity of females. However, little is known about the effect of male nutritional status on the female reproductive traits in migratory insect species, particularly when females experience nutrient shortage and have to choose between reproduction and migration. Here, Cnaphalocrocis medinalis, a migratory rice pest in Asia, was studied to explore this issue. Our results showed that in male moths fed with honey solution, their gonads had higher energy content than gonads of starved males, resulting in increased energy content of the bursa copulatrix of females after mating with fed males. Such females showed increased mating frequency, fecundity and longevity compared to females mating with starved males, indicating that male moths deliver nuptial gifts to females and improve their reproductive performance. However, when females were starved, only about 45% mated, with just a single copulation, regardless of male nutritional status. Starved females showed lower fecundity, and a longer pre-oviposition period (indicating a greater propensity to migrate), compared to fed females. However, copulation still significantly extended their longevity. These results suggest that starved females invest in migration to escape deteriorating habitats, rather than investing the nuptial gift to increased fecundity. Our results further our understanding of the reproductive adaptability of migratory insects under conditions of food stress.

Differential impacts of six insecticides on a mealybug and its coccinellid predator

Broad-spectrum insecticides may disrupt biological control and cause pest resurgence due to their negative impacts on natural enemies. The preservation of sustainable pest control in agroecosystems requires parallel assessments of insecticide toxicity to target pests and their key natural enemies. In the present study, the leaf dipping method was used to evaluate the relative toxicity of six insecticides to the striped mealybug, Ferrisia dasylirii (Cockerell) (Hemiptera: Pseudococcidae) and its predator, Tenuisvalvae notata (Mulsant) (Coleoptera: Coccinellidae). Three neurotoxic insecticides, lambda-cyhalothrin, methidathion and thiamethoxam, caused complete mortality of both pest and predator when applied at their highest field rates. In contrast, lufenuron, pymetrozine and pyriproxyfen caused moderate mortality of third-instar mealybug nymphs, and exhibited low or no toxicity to either larvae or adults of the lady beetle. At field rates, lufenuron and pymetrozine had negligible effects on prey consumption, development or reproduction of T. notata, but adults failed to emerge from pupae when fourth instar larvae were exposed to pyriproxyfen. In addition, pyriproxyfen caused temporary sterility; T. notata females laid non-viable eggs for three days after exposure, but recovered egg fertility thereafter. Our results indicate that the three neurotoxic insecticides can potentially control F. dasylirii, but are hazardous to its natural predator. In contrast, lufenuron and pymetrozine appear compatible with T. notata, although they appear less effective against the mealybug. Although the acute toxicity of pyriproxyfen to T. notata was low, some pupal mortality and reduced egg fertility suggest that this material could impede the predator's numerical response to mealybug populations.

Alternative food sources for the ladybird Brumoides foudrasii (Mulsant) (Coleoptera: Coccinellidae)

The predator Brumoides foudrasii (Mulsant) (Coleoptera, Coccinellidae) has been naturally found in plants infested by mealybugs. In this study, the striped mealybug Ferrisia dasylirii (Cockerell) (Hemiptera, Pseudococcidae) and Anagasta kuehniella Zeller (Lepidoptera, Pyralidae) eggs were evaluated as diets for the development and reproduction of B. foudrasii. Brumoides foudrasii immatures developed faster when fed with A. kuehniella eggs than when fed with F. dasylirii. However, the survival and longevity of B. foudrasii adults were not affected by the diets. Oviposition was more frequent when B. foudrasii females were fed with F. dasylirii (95%) than those fed with A. kuehniella eggs (65%). Brumoides foudrasii females fed with F. dasylirii were 2.5 times more fecund than those fed with A. kuehniella eggs. Although both diets may be considered proper for B. foudrasii, A. kuehniella eggs were more suitable for immature development, while F. darsyrili provided more nutritious resources for adult biological parameters as oviposition period, egg viability and fecundity. These results suggests that this predator can play an important role in regulating populations of the stripped mealybug F. dasylirii in the field.

New species and new records of Manota Williston from Colombia, Brazilian Amazonia, and Costa Rica (Diptera, Mycetophilidae)

The following five species are described as new: Manotaclavasp. n. (Colombia), Manotamultilobatasp. n. (Colombia), Manotaperplexasp. n. (Costa Rica), Manotasetilobatasp. n. (Colombia) and Manotasubaristatasp. n. (Colombia). In addition, new records for the following 11 species are presented: Manotaacuminata Jaschhof & Hippa, 2005 (Costa Rica), Manotaarenalensis Jaschhof & Hippa, 2005 (Costa Rica), Manotacorcovado Jaschhof & Hippa, 2005 (Costa Rica), Manotacostaricensis Jaschhof & Hippa, 2005 (Costa Rica), Manotadiversiseta Jaschhof & Hippa, 2005 (Colombia, Brazilian Amazonia, Costa Rica), Manotaminutula Hippa, Kurina & Sääksjärvi, 2017 (Brazilian Amazonia), Manotamultisetosa Jaschhof & Hippa, 2005 (Costa Rica), Manotaparva Jaschhof & Hippa, 2005 (Colombia, Costa Rica), Manotapisinna Hippa & Kurina, 2013 (Brazilian Amazonia), Manotaspinosa Jaschhof & Hippa, 2005 (Colombia) and Manotasquamulata Jaschhof & Hippa, 2005 (Costa Rica). Distribution patterns include (1) species known only locally in Costa Rica or Colombia, (2) distributions connecting Central America to west Andes lowlands, and (3) north-west Neotropical components, extending from Central America to Brazilian Amazonia. The possible biogeographical and taxonomical context of Manota species with a widespread distribution is considered.

Temperature- and Relative Humidity-Dependent Life History Traits of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) on Hibiscus rosa-sinensis (Malvales: Malvaceae)

Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), a worldwide distributive invasive pest, originated from the United States, and it was first reported in Guangdong province, China, in 2008. The effects of temperature and relative humidity (RH) on the life history traits of P. solenopsis on Hibiscus rosa-sinensis L. (Malvales: Malvaceae) were studied at seven constant temperatures (15, 20, 25, 27.5, 30, 32.5, and 35°C) and three RHs (45, 60, and 75%). The results showed that temperature, RH, and their interactions significantly influenced the life history traits of P. solenopsis. First instar was the most sensitive stage to extreme temperatures with very low survival rates at 15 and 35°C. At 25-32.5°C and the three RHs, the developmental periods of entire immature stage were shorter with values between 12.5-18.6 d. The minimum threshold temperature and the effective accumulative temperature for the pest to complete one generation were 13.2°C and 393.7 degree-days, respectively. The percentage and longevity of female adults significantly differed among different treatments. It failed to complete development at 15 or 35°C and the three RHs. Female fecundity reached the maximum value at 27.5°C and 45% RH. The intrinsic rate for increase (r), the net reproductive rate (R0), and the finite rate of increase (λ) reached the maximum values at 27.5°C and 45% RH (0.22 d(-1), 244.6 hatched eggs, and 1.25 d(-1), respectively). Therefore, we conclude that 27.5°C and 45% RH are the optimum conditions for the population development of the pest.

First record of Neoempheria Osten Sacken (Diptera, Mycetophilidae) biology in the Neotropical region, with associations between its larvae and fungi

Background

Members of the family Mycetophilidae (Diptera) have life cycles that are typically associated with fungus. Their biology is relatively well known in the Palaearctic, though other regions are poorly known, and there are no associations recorded between mycetophilid immatures and fungi in the Neotropical region. Here we report the first association between a mycetophilid—Neoempheriapuncticoxa Edwards—and fungi in this region. Immatures of N.puncticoxa were collected on fungi and some were reared in the laboratory until adult emergence. The immature stages and adult of N.puncticoxa are described and re-described respectively, and high resolution images and illustrations of the habitus, wings, thorax, male and female terminalia, immatures, and in situ specimens are given.

New information

We report the first association between Mycetophilidae and fungi in the Neotropical region.

The Mycetophilaruficollis Meigen (Diptera, Mycetophilidae) group in Europe: elucidating species delimitation with COI and ITS2 sequence data

European species of the Mycetophilaruficollis group are compared on the basis of morphology and sequences of mitochondrial cytochrome oxidase subunit one (COI) and the ITS2 region of nuclear ribosomal DNA. The study represents the first evaluation of morphology-based species delimitation of closely related fungus gnat species by applying molecular information. Detailed descriptions and illustrations of the male terminalia are presented along with a key for the identification of all nine European species of the group. Phylogenetic analyses of molecular data generally supported the morphological species discrimination. The barcoding region of COI superseded ITS2 rDNA in resolving species. In the COI barcoding region interspecific differences ranged from 2.9 to 10.6% and the intraspecific distance from 0.08 to 0.8%. Only COI data distinguished between the similar and closely related Mycetophilaichneumonea and Mycetophilauninotata of which the latter was observed to include cryptic species. The host range of some species is suggested to be narrower than previously considered and to depend on the forest type. Presented evidence indicates the importance of analysing sequence data of morphologically very similar mycetophages reared from identified host fungi for elucidating species delimitation as well as their geographic and host ranges. New country records, viz. Estonia for Mycetophilaevanida, Georgia for Mycetophilaichneumonea, Mycetophilaidonea and Mycetophilaruficollis, and Norway for Mycetophilastrobli, widen the known distribution ranges of these species.