Leg impairment affects the reproductive attributes of a ladybird,Menochilus sexmaculatus (Fabricius)

Natural injuries and their causes have recently garnered attention amongst researchers, however the effects of these injuries on life history traits are still sparsely investigated. In the few studies that have been conducted injuries are known to have a debilitating effect on male virility and reproductive performance. Thus the effect of leg injuries in males on mating behaviour and reproductive output in the ladybird beetle, Menochilus sexmaculatus was investigated. This is the first study on the effect of injury on any life history trait in Coccinellidae. The legs of the male were amputated at three different joints on the same side and opposite sides for one leg or two legs. These amputated males were paired with uninjured females and the mating behaviour and subsequent reproductive output was observed. Time to commence mating, latent period and mating duration in impaired males were observed and were all found to be higher than that of uninjured males. Fecundity and percent egg viability were reduced in all impaired male pairs. Males with physical disability were found to copulate for an extended duration, perhaps to ensure maximum paternity.     

Effects of temperature on the expression of elytral colour polymorphism in the ladybird beetle,Menochilus sexmaculatus (Coleoptera: Coccinellidae)

The ladybird beetle, Menochilus sexmaculatus (Fabricius), has a remarkable elytral colour polymorphism composed of black and red. In the present study, we investigated the effect of temperature on growth from the first instar larva to the pupal stage, as well as maternal morph types on the phenotypic expression of the elytral colour morph in a polymorphic population from Osaka, Japan. Female individuals of three different elytral colour morphs were collected from a wild population, and hatchlings from each female were divided into three groups, which were reared at three constant temperatures: 20 °C, 25 °C, and 30 °C. The phenotypic frequency of F₁ adults indicated that the elytral morph type was determined by genetic factors, but not by growth temperatures. Namely, type A (almost black morph) was the most abundant in F₁ from type A mothers (Male: 52.6%; Female: 32.3%); and types B (four small-dotted morph) and F (four medium-dotted morph) were the most abundant from type B (Male: 56.7%; Female: 53.3%) and type G (four larger-dotted morph) mothers (Male: 33.3%; Female: 31.3%), respectively. Therefore, the expression of elytral colour polymorphism in the Osaka, Japan population is likely to have a genetic basis contingent on parental morphs, rather than a phenotypic plasticity associated with growth temperatures.     

Age specific mating incidence and reproductive behavior of the ladybird beetle,Anegleis cardoni (Weise) (Coleoptera: Coccinellidae)

Age specific mating incidence, mating behavior, mate recognition cues and effect of sexual status on mating of ladybird beetle, Anegleis cardoni (Weise) (Coleoptera: Coccinellidae) were studied in detail. The mating duration was very short (14.40 ± 0.72 min) in comparison to other ladybirds. Courtship was male dominated and was displayed in steps, viz. approach, watch, examine, sharp turns, mount, attempt and mate. Sharp turns is an additional behavior observed during courtship in this ladybird, and is characterized by sharp turning movements towards the mate, and is undertaken by both males and females. Active mating of A. cardoni involved multiple strokes of the aedeagus. Mating duration and the number of strokes were higher in unmated males than in mated ones. Results reveal that physical cues probably play a role in the initiation of courtship, while chemical signals are probably involved in the continuation of courtship, culminating in intromission. The removal of male antennae and obscurity of elytral patterns significantly decreased mating success, whereas female antennal ablation and obscuring of the pronotum did not affect mate recognition.     

Effects of temperature on reproductive output, egg provisioning, juvenile hormone and vitellogenin titres in the butterfly Bicyclus anynana

Environmentally induced phenotypic plasticity is common in nature. Hormones, affecting multiple traits and signaling to a variety of distant target tissues, provide a mechanistic link between environments, genes and trait expression, and may therefore well be involved in the regulation phenotypic plasticity. Here, we investigate whether in the tropical butterfly Bicyclus anynana temperature-mediated plasticity in egg size and number, with fewer but larger eggs produced at lower temperatures and vice versa, is under control of juvenile hormone, and whether different temperatures cause differences in egg composition. Female B. anynana butterflies showed the expected response to temperature, however, we found no evidence for an involvement of juvenile hormone. Neither haemolymph JH II and JH III titres nor vitellogenin levels differed across temperatures. The smaller eggs produced at the higher temperature contained relatively higher amounts of water, free carbohydrates and proteins, but relatively lower amounts of lipids. While these smaller eggs had a lower absolute energy content, total reproductive investment was higher at the higher temperature (due to a higher fecundity). Overall, our study indicates that temperature-mediated plasticity in reproduction in B. anynana is mechanistically related to a biophysical model, with oocyte production (differentiation) and oocyte growth (vitellogenesis) having differential temperature sensitivities.     

Temperature-dependent development and oviposition models of Illeis koebelei (Coleoptera: Coccinellidae)

The yellow ladybeetle, Illeis koebelei Timberlake, is a potential biological agent for powdery mildew. The objective of this study was to construct development and oviposition models of I. koebelei. Development experiment was conducted at eight temperatures ranging from 15.4 to 39.5?°C. Development rates were well fitted with linear and nonlinear models. Lower developmental thresholds for egg, first instar, second instar, third instar, and fourth instar larva, pre-pupa, pupa, and total immature stage were estimated to be 3.6, 12.7, 12.1, 11.3, 11.3, 12.8, 14.7, and 14.2?°C, respectively. Their respective thermal requirements in degree days (DD) were 86.6, 16.0, 22.5, 30.2, 49.3, 14.5, 43.8 and 217.4, respectively. Survivorship was the highest at 25.1?°C for immatures. Oviposition experiment was conducted at nine temperatures, ranging from 15.4 to 35.3?°C. Mean fecundity ranged from 18.6 eggs at 29.3?°C to 205.3 eggs at 20.3?°C. It was well described by extreme value function. Adult survival and cumulative oviposition rates of I. koebelei were fitted to a sigmoid function and a two-parameter Weibull function, respectively. Findings of this study provide basic information for ecology of I. koebelei. They can be used to optimize environmental conditions for mass-rearing and shipping, comparing optimal occurrence conditions between I. koebelei and powdery mildew, and forecasting phenology and population dynamics of I. koebelei in the fields.     

The decline of native coccinellids (Coleoptera: Coccinellidae) in the United States and Canada

Reviewing published coccinellid surveys we found that the number of adventive species has increased steadily over the last century while the average proportion of native individuals has remained fairly constant until 1987 followed by a rapid decrease between 1987 and 2006. Seven long-term studies indicated that the total density of coccinellids increased by an average of 14% following establishment of adventive species, but this increase was not significant and in 4 of 7 cases the total density of coccinellids actually decreased following establishment. Similarly, no significant difference was found in comparisons of diversity across all studies. These results illustrate that even with multiple long-term data sets it is currently difficult to make any general conclusions regarding the impact adventive coccinellids have had on native coccinellid assemblages. However, it is clear that specific systems and species have seen major shifts in recent years. For example, adventives have become the dominant species in a third of the assemblages where they are found. Focusing on two formerly common native species, Adalia bipunctata and Coccinella novemnotata, we show they have become rare in their former ranges and discuss potential explanations for this phenomenon.     

Effects of temperature on development, survival, longevity, and fecundity of the Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) predator, Axinoscymnus cardilobus (Coleoptera: Coccinellidae)

Axinoscymnus cardilobus (Homoptera: Aleyrodidae) is an important predator of Bemisia tabaci (Coleoptera: Coccinellidae) that occurs in high population density of B. tabaci. Temperature among other factors is observed to play an important role in the development of arthropods. The effect of temperature on the development of A. cardilobus was studied at seven constant temperature regimes (14, 17, 20, 23, 26, 29, 32 °C). The results indicated that the duration of egg, larval and pupal stages were significantly influenced by increased temperature. The rate of development gradually increased with increase in temperature from 14 °C to 26 °C, but declined from 26 °C to 32 °C. The survival rates of different insect stages were stable at temperatures between 20 °C and 26 °C, but at extreme temperatures of 32 °C and 14 °C, a sharp decrease was evident. Ovipositional period of the female decreased when temperatures were increased from 17 °C to 32 °C. The highest fecundity of the female (225.7 eggs per female) was recorded at 23 °C. Life tables of A. cardilobus were constructed based on the experimental results at temperatures of 14–32 °C. The reproductive rate (R₀), the innate capacity for increase (r_m) and the finite rate of increase (λ) reached the maximum values at 23 °C, of 70.7, 0.059 and 1.062, respectively. The mean generation time (T) decreased with increased temperature from 17 °C to 32 °C, the highest and least values recorded at 17 °C and 32 °C were 112.7 and 38.7, respectively. These results offer valuable insight on the importation and establishment of A. cardilobus into new environments with diverse temperature regimes.     

An artificial diet for continuous maintenance of Coccinella septempunctata adults (Coleoptera: Coccinellidae)

An artificial diet was developed for continuous maintenance of ladybird beetle (Coccinella septempunctata) adults. This beetle is an important biocontrol agent for greenhouse crops. Several biological parameters were measured and compared between colonies fed the artificial diet over eight successive generations, and colonies fed aphids. Weight, survival rates from 1st to 4th instar, pupation rate, and emergence rate were similar for both colonies, but the sex ratio (♀:♂) of the artificial diet-fed colony was higher than that of the aphid-fed colony. These results suggest that this artificial diet could meet the basic needs for the successive rearing of C. septempunctata adults. The prepared diet, which is semi-solid, provides suitable moisture for C. septempunctata, and the diet ingredients are inexpensive and relatively easy to prepare. This diet and rearing technique offers a very useful approach for mass production of C. septempunctata.     

Impacts of very warm temperature on egg production rates of three Acartiidae (Crustacea,Copepoda) in a Northern African lagoon

The daily Egg Production Rate (EPR) of the three Acartiidae copepods namely Acartia clausi, Paracartia latisetosa and Paracartia grani in the North Lagoon of Tunis was compared to temperature and food availability every season from March, 2003 to February, 2004 corresponding to the major seasonal peaks of their abundance and over a 20-days period. The daily EPR was evaluated by assuming a direct correlation with chlorophyll a, particulate organic carbon (POC), and some easily extractable macromolecular compounds from the seston, such as proteins, carbohydrates and lipids. The results showed significant differences in EPR between seasons and species. Temperature and salinity negatively affected the fecundity of A. clausi and positively that of P. latisetosa and P. grani. The A. clausi EPR was supported by chlorophyll a and sestonic proteins while that of P. latisetosa and P. grani correlated with POC suggesting that these two taxa feed on microzooplankton and detritus more than on phytoplankton. Overall, EPR data showed potential population recruitment evidently the highest in P. latisetosa in summer, P. grani in autumn and A. clausi in winter. Our results indicate that temperature and food quality are the determining factors of both abundance and reproduction of the copepods under study.     

Effect of entomopathogenic nematodes on Plectrodera scalator (Fabricius) (Coleoptera: Cerambycidae)

Entomopathogenic nematodes were screened for efficacy against the cottonwood borer, Plectrodera scalator (Fabricius). Steinernema feltiae SN and S. carpocapsae All killed 58 and 50% of larvae, respectively, in filter paper bioassays but less than 10% in diet cup bioassays. S. glaseri NJ, S. riobrave TX, and H. indica MG-13 killed less than 10% of larvae in both assays. H. marelata IN was ineffective in the diet cup bioassay and killed 12.9% of larvae in a filter paper bioassay. The nematode isolates we tested are not suitable for use as biological control agents against P. scalator.     

Sibling and non-sibling cannibalism by larvae of a lady beetleHarmonia axyridis Pallas (Coleoptera: Coccinellidae) in the field

Sibling (cannibalism among siblings) and non-sibling cannibalism (cannibalism among non-siblings) were studied in a natural population of a lady beetle, Harmonia axyridisPallas . Of all the eggs laid (n=2269), 24.76% (n=562) were killed by sibling cannibalism and 36.10% (n=819) were killed by non-sibling cannibalism. Sibling cannibalism occurred constantly and intensively in most egg batches throughout the entire oviposition period. On the other hand, non-sibling cannibalism was more intense in the middle and late oviposition periods, and when the egg batches were close to an aphid colony. This may be due to the high density of H. axyridis larvae relative to aphid density in the middle and late oviposition periods and also the larvae searching intensively near an aphid colony.     

Desiccation and egg viability of the ragwort flea beetle,Longitarsus flavicornis (Coleoptera: Chrysomelidae)

A study was conducted to investigate the effect of desiccation on the survival of eggs of Longitarsus flavicornis. Eclosion of L. flavicornis eggs in laboratory trials decreased with increasing desiccation time between 0 days (93% hatching) and 42 days (no egg hatching) at 50±2% relative humidity and 23±2°C. Probit analysis indicated that 25, 50 and 99% mortality of L. flavicornis eggs occurred after 5.7, 9.3 and 50.4 days desiccation, respectively. Egg development varied between a minimum of 8 days at 7 days desiccation to a maximum of 15 days at 28 days desiccation. Hatching span did not differ between treatments with all eggs hatching within 12 days of each other. A relative humidity of 88–100% was measured under ragwort rosettes in non-drought field conditions. This would be expected to facilitate successful egg eclosion. However, the occurrence of summer drought could be detrimental to egg survival.     

黄曲条跳甲卵分离器的设计和应用

根据比重的原理和双层过滤的方法 ,设计和制作了黄曲条跳甲卵的分离装置。该装置结构简单 ,易于操作。使用这种分离器 ,黄曲条跳甲卵的田间检出率可达 82 %以上。     

Tidal influence on the evolution of egg size in the grunions (Leuresthes,Atherinidae)

Synopsis The duration of natural in-beach-sand incubation of Gulf of California and California grunion embryos is dictated by the tidally-driven wave activity in their respective habitats. Analyses of these tidal regimes reveal that the incubation period can be three times longer on beaches of the California coast than on those of the northern Gulf.In response to the more irregular tides of California, Leuresthes tenuis, the less primitive of the two species, has evolved an egg volume 310% larger than the Gulf grunion, L. sardina. The. larger egg not only supplies greater yolk reserves for differentiation, growth and maintenance, but also produces a larger embryo. The more abundant yolk stores and greater embryo size helps California grunion embryos to remain viable in the sand longer than those of the Gulf grunion.     

Prey quality dependent growth,development and reproduction of a biocontrol agent,Cheilomenes sexmaculata (Fabricius) (Coleoptera: Coccinellidae)

Growth, development and reproduction of a ladybird beetle, Cheilomenes sexmaculata (Fabricius) were investigated in relation to seven aphid species, viz. Aphis craccivora Koch, Aphis gossypii Glover, Rhopalosiphum maidis (Fitch), Myzus persicae (Sulzer), Uroleucon compositae (Theobald), Lipaphis erysimi (Kaltenbach) and Aphis nerii Boyer de Fonscolombe on specific hosts. Maximum prey consumption, percent larval survival, developmental rate, weight of different life stages, percent adult emergence, adult longevity and fecundity of C. sexmaculata were recorded on A. craccivora, and minimum on A. nerii. A linear relationship was found between development rate and weight of adult, daily prey consumption and relative growth rate, log weights of adult males and females, and female longevity and total fecundity. On the basis of overall performance of ladybird the order of suitability of prey species was A. craccivora>A. gossypii>R. maidis>M. persicae>U. compositae>L. erysimi>A. nerii.     

Effect of emergence time on the reproductive parameters of mass-reared Anastrepha ludens (Diptera: Tephritidae) flies

In the mass rearing of fruit flies, the adult emergence time is gradual, due to factors such as variation in food consumption in the larval phase, the female oviposition behavior and environmental conditions, among others. Here, we investigate the effect of emergence time on sex ratio, fecundity, fertility, body size and mating performance in mass-reared Anastrepha ludens (Diptera: Tephritidae) flies. The results of the study indicated that the emergence of the flies is gradual and lasts approximately 96?h, but the highest proportion of emerged flies was observed at 48?h. The flies emerging at 24 and 48?h showed higher fecundity than those emerging at 72 and 96?h, but there were no significant differences in the sex ratio, fertility and male mating performance. Body size was significant, the flies that emerged at 24, 48 and 72?h were bigger than those emerged at 96?h. The discussion focuses on the effect of emergence time on the rearing processes and release of the Mexican fruit fly.     

The value of an egg: resource reallocation in ladybirds (Coleoptera: Coccinellidae) infected with male-killing bacteria

Male-killing bacteria are thought to persist in host populations by vertical transmission and conferring direct and/or indirect fitness benefits to their hosts. Here, we test the role of indirect fitness benefits accrued from resource reallocation in species that engage in sibling egg cannibalism. We found that a single-egg meal significantly increased larval survival in 12 ladybird species, but the value of an egg (to survival) differed substantially between species. Next, we tested the impact of three male-killing bacteria on larval survival in one ladybird species, Adalia bipunctata. Spiroplasma reduced larval survival, whereas Wolbachia and Rickettsia had no effect. However, Spiroplasma-infected larvae showed the greatest response to a single-egg meal. The indirect fitness benefit obtained from a single egg is thus so large that even male-killing bacteria with direct fitness costs can persist in host populations. This study supports the hypothesis that fitness compensation via resource reallocation can explain male-killing bacteria persistence.     

Infection of Harmonia axyridis (Coleoptera: Coccinellidae) by Hesperomyces virescens (Ascomycetes: Laboulbeniales): role of mating status and aggregation behavior

The ectoparasitic fungus Hesperomyces virescens was studied on Harmonia axyridis in North Carolina, in the southeastern United States. A primary goal was to investigate transmission of the disease by examining the correlation between the pattern of fungal infection and seasonal change in host behavior. Beetles were collected as they arrived at their winter quarters at two sites; in one site they were also subsampled at mid- and late winter. Insects were sexed and weighed, fungal thalli were counted, and their location on the host body mapped; spermathecae of females were examined for sperm. Infection levels varied between sites, differed significantly between the sexes in one site but not the other, and increased by approximately 40% during winter. The distribution of thalli on the body changed seasonally, in concert with behavioral changes in the host. At fall flight, thalli were found most often on the posterior elytra of mated females, virgin females, and males. This is suggestive that the disease had been spread among both sexes via successful and failed copulation attempts; however, the relatively low incidence of infection on the male venter does not fit the sexual transmission scenario. During winter, thallus location shifts in concert with beetle aggregation behavior, with infections more often located on the head and legs. Fresh weight of beetles decreased by approx. 20% during winter, but was not affected by disease status. Prior to spring flight, uninfected females were preferred as mating partners, but the probable relationship between female age and infection status complicates interpretation of the data.     

Delayed mating and the reproductive fitness of aponomma hydrosauri (Acari: Ixodidae)

, and 1992. Delayed mating and the reproductive fitness of Aponomma hydrosauri (Acari: Ixodidae). International Journal for Parasitology 22: 1197–1200. This study examines whether delayed mating influences the reproductive fitness of female reptile ticks, Aponomma hydrosauri. Delayed mating was induced by the prevention of male attachment to hosts for 20 or 40 days after females had been attached. The results showed that delayed mating had no significant influence on the number of viable progeny produced by female ticks. This may represent an important advantage for colonizing Ap. hydrosauri females in marginal population areas, particularly at parapatric boundaries.