Impact of Lantana camara hexane extract on survival,growth and development of Dysdercus koenigii Fabricius (Heteroptera: Pyrrhocoriedae)

Present research work investigated the impact of hexane extract of Lantana camara leaves on the survival, survival duration, growth and development of the Dysdercus koenigii. Newly emerged fifth instar nymphs were exposed to nine concentrations viz. 10%, 5%, 2.5%, 1.25% 0.1%, 0.05%, 0.025%, 0.0125% and 0.00625% of the extract by ‘dry film residual method’ for 24 h. The results indicated that the survival and the growth of the nymphs decreased with increasing concentrations of the L. camara extract. The nymphs presented developmental malformation including incomplete moulting followed by death of the moulting nymphs, supernumerary nymphal instars, adults with wing deformities, and adults with exuviae attached to the body. The GC–MS analysis of the extract indicated presence of phytoconstituents with insecticidal activities, and intermediates of the juvenile hormone biosynthetic pathway. It was surmised that these intermediates individually or synergistically influence JH biosynthesis. L. camara extract causes mortality, inhibits growth and development and results in developmental anomalies in the D. koenigii thus indicated its potentials in the ‘integrated pest management’.     

Effects of Ocimum sanctum hexane extract on survival and development of Dysdercus koenigii Fabricius (Heteroptera: Pyrrhocoriedae)

Abstract

The effects of hexane extract of Ocimum sanctum leaves on the survival, longevity, growth and development of the Dysdercus koenigii Fabricius were investigated. Newly emerged fifth instar nymphs were exposed to nine concentrations ranging from 0.00625% to 10% of the extract for 24?h by “dry film residual method.” The results indicated that the extract has adverse effect on various life activities studied. The effects were dose related; exposure to a dose of 5% or more causes high mortality. Normal adults were not produced from the nymphs treated with extract concentrations of 1.25% or more. The treated nymphs exhibited developmental malformation. The gas chromatography and mass spectroscopy analysis of the extract revealed presence of chemical compounds having insecticidal and juvenile hormone (JH) mimicking activities. Some of the compounds act as precursors of JH biosynthetic pathways. Therefore, these compounds may individually or synergistically can be used in management of D. koenigii and other insect pests.     

Endocrine manipulations and ontogenesis of male sexual behaviour in Locusta: studies on azadirachtin-induced over-aged nymphs

ABSTRACT. Dose-response relations of the moult-inhibitory and lethal effects of azadirachtin (AZA) injected into fifth and fourth instar hoppers of Locusta migratoria migratorioides are presented. The optimal dose for obtaining maximum number of long-surviving over-aged nymphs is 1.6 and 1.0 μg of AZA per insect for young fifth and fourth instar nymphs, respectively. Over-aged male nymphs are capable of exhibiting sexual behaviour. The mating behaviour of fifth instar over-aged male nymphs, and of chemically allatectomized but otherwise similar over-aged male nymphs (obtained by combined precocene treatment and injection of AZA), with and without injections of exogenous Juvenile Hormone III (JH), is investigated quantitatively; the results are compared with those obtained for normal, chemically allatectomized, and chemically allatectomized plus JH-injected adult males. Over-aged fifth instar male nymphs show a low intensity of mating behaviour and in chemically allatectomized ones this intensity is even lower. Injections of JH intensify the mating behaviour of chemically allatectomized fifth instar over-aged male nymphs in a dose-dependent way, but less markedly so than in chemically allatectomized adult males. We conclude that the intensity of male mating behaviour of the over-aged nymphs is subnormal and their response to the mating behaviour intensifying effect of the JH is weaker than that of adult males. The relations between endocrine factors and ethological ontogenesis of male sexual behaviour in locusts are discussed.     

Influence of azadirachtin on development and reproduction of Nezara viridula L. (Het., Pentatomidae)

Abstract:  The potential of azadirachtin as an insect growth regulator was evaluated in Nezara viridula L. by applying different doses to fifth instar nymphs. At doses of 200–500 ng per insect almost all the individuals died during moulting to adults and the survivors showed a great number of nymphal characteristics, and also died very soon after. At lower doses, from 2 to 50 ng per insect, approximately 50% of the adults seemed normal. No effect was observed during the last nymphal instar, even at the highest dose applied. The fertility and fecundity of adults, males and females, developing from nymphs treated with different low doses of azadirachtin were also studied. When azadirachtin was applied at 20 ng per insect on fifth instar nymphs, females developing from these nymphs showed a conspicuous reduction of fecundity. This same effect was evident when untreated females mated with males obtained from treated nymphs. Finally, azadirachtin applied at 1  μ g/cm² to the oviposition surface showed a remarkable oviposition repellency.     

The interaction of surface and dust particle size on the pick-up and grooming behaviour of the German cockroachBlattella germanica

The relationship between the particle size of an inert silica dust, its up-take from different surfaces and the grooming behaviour of males, gravid females, and fifth and sixth instar nymphs of the German cockroachBlattella germanica (Dictyoptera: Blattellidae) (L.) was investigated. The normal grooming behaviour of gravid females, nymphs and males differed according to sex and age. The gravid females and nymphs exhibited greater grooming activity than the males, especially of the antennae and the legs. Gravid females, nymphs, and adult males exhibited increased grooming activity after exposure to dust in the size range 0.5–63 μm, but there was no significant difference in grooming behaviour from the control when cockroaches were exposed to dust sizes greater than 70 μm. Antennal grooming by males was greater than leg grooming when exposed to all dust sizes, except size particles ranging 4.5–7.5 μm. A dust pick-up experiment indicated that the average amount of dust transferred toB. germanica is affected by particle size, the porosity of the treated surface, and the sex and age of the cockroaches. Gravid females picked up greater amounts of dust than fifth and sixth instar nymphs, which in turn picked up more dust than males. Silica dust particles (0.5–7.5 μm) were picked up more effectively than larger particle sizes, by all three categories, males, females and fifth and sixth instar nymphs of cockroach on all three test surfaces plastic, ceramic and unpainted plywood. Plywood was the least effective surface for transfer of dust, of all sizes, to males, females and nymphs.     

Endocrine manipulations,juvenile hormone and ontogenesis of male sexual behaviour in locusts

By injection of azadirachtin (AZA) to 5th instar hoppers of Locusta migratoria migratorioides, “over-aged” nymphs were produced, some of which survived for long periods without moulting to adults. Such over-aged male nymphs exhibited mating behaviour belatedly, though at a lower intensity than normal adults. Juvenile hormone (JH) markedly intensifies male sexual behaviour in crowded adult (6th instar) Locusta; thus, the lower intensity of sexual behaviour of the over-aged nymphs might have been caused by a low endogenous JH titre, or by a weaker response to the hormone. To clarify this point, chemically allatectomized over-aged 5th instar nymphs were produced by combined treatment with precocene and AZA. These exhibited a very low intensity of mating behaviour. Injections of exogenous JH III intensified the mating behaviour of the chemically allatectomized over-aged 5th instar male nymphs in a dose-dependent way, but the effect was weaker than in chemically allatectomized adult males. AZA-induced over-aged 4th instar male Locusta hoppers also exhibited mating behaviour. By injection of AZA, 5th instar over-aged hoppers of Schistocerca gregaria were also produced. Males showed mating behaviour belatedly, despite the fact that JH completely controls male sexual behaviour in this species. The intensity of this behaviour was again lower than in adults. Interrelations between integumental morphogenesis, “ethogenesis” of male sexual behaviour, and endocrine factors in locusts are discussed.     

Reduced female mating receptivity and activation of oviposition in two Callosobruchus species due to injection of biogenic amines

Analyses of proximate mechanisms that control mating and oviposition behaviours in insects are important because they link behavioural ecology and physiology. Recently, seed beetles have been used as models to study evolution of female multiple mating and cost of reproduction including mating. In the present study, we investigated the effects of biogenic amines into the abdomens of females of two Callosobruchus species, Callosobruchus chinensis and Callosobruchus maculatus, on mating receptivity and oviposition behaviour. In C. chinensis, injection of octopamine and tyramine reduced receptivity to mating and tyramine and serotonin increased the number of eggs laid. Similarly, injection of tyramine reduced the receptivity of females and increased the number of eggs laid by females of C. maculatus. These results show the possibility that biogenic amines control mating receptivity and oviposition behaviour in females of two Callosobruchus species.     

Disruption of aggregation behaviour of oriental migratory locusts (Locusta migratoria manilensis) infected with Nosema locustae

Abstract:  The effect of Nosema locustae infection on the aggregation behaviour of the oriental migratory locust, Locusta migratoria manilensis , was studied using a two-choice arena olfactometer and electroantennography (EAG). Infected locusts had low antennal sensitivity and aggregation responses to faecal extracts and to locust body volatiles. Infected fifth instar nymphs had significantly lower aggregation index than the uninfected nymphs, although with fourth instars the effect on aggregation behaviour only occurred in infected females. With regard to antennal receptor sensitivity, infected adult locusts had significantly lower EAG amplitudes in response to extracts from faeces of the adult males. The effect was most pronounced in female locusts. In contrast, there was no significant difference in the EAG responses between the fifth instar male and female nymphs. Further analysis revealed that EAG responses of fifth instar nymphs and adults infected with N. locustae to the faecal extract and volatiles from fifth instar solitary-reared nymphs were not significantly affected. In contrast, infected nymphs and adults had remarkably low EAG amplitudes for the remaining stimuli.     

Life history parameters of the microtype parasitoid fly Pales pavida (Diptera: Tachinidae), and effects of host age and number of eggs ingested by host on parasitism success

With the aim of developing better procedures for rearing the microtype tachinid fly Pales pavida (Meigen), we performed ecological studies in the laboratory using the natural host Mythimna separata (Walker), investigating larval development, mating behaviour, individual oviposition patterns and relationships between parasitisation and number of eggs ingested (NEI) per host. The host instar at the time of parasitoid egg ingestion significantly affected the development time of the immature parasitoid: development took longer when the hosts ingested eggs when at the fifth instar than at the sixth (last) instar. There was no difficulty obtaining mated females in the laboratory when day 0–1 female flies were kept with day 2–4 males. Mean lifetime fecundity was 5805?±?568 eggs per female. Daily rates of oviposition by individual females varied widely; the greatest number of eggs laid in a day was exactly 1700. When the NEI by day 1 fifth instars or day 0 or 3 last instars was 1, 3, 6 or 10, the parasitisation percentage tended to increase with increasing NEI, although it did not differ significantly between NEI 6 and 10. Therefore, the percentage adult emergence per egg ingested decreased from NEI 6 to 10, particularly in the case of last instars. Using day 0 last instars, with six eggs ingested per host, should increase parasitisation rates and shorten the development time of the parasitoid for rearing.     

Re-evaluation of the role of corpora cardiaca in calling and oviposition behaviour of giant silk moths

Re-investigation of the role of the corpora cardiaca in the reproductive behaviour of the giant silkmoths, Hyalophora cecropia and Antheraea polyphemus, showed that this pair of glands plays no essential role, either in “calling” behaviour by virgin females or in increased oviposition due to mating. Removal of corpora cardiaca-corpora allata complexes, either from diapausing pupae or from freshly eclosed adult females, had no effect on the calling behaviour or on its timing in either species. Moreover after mating, these operated females laid eggs in the typical mated oviposition pattern. Furthermore, females in which there was only a nervous connection between the brain and the abdomen but no haemolymph circulation called normally and oviposited after mating.Although the corpora cardiaca were not essential for calling behaviour, hormogenates of corpora cardiaca-corpora allata complexes and blood from calling or ovipositing females induced a typical “calling” response in 30–60% of the isolated virgin H. cecropia abdomens tested. This activity was not species-specific as it was also found in Manduca sexta, but the restriction of major activity to corpora cardiaca extracts and haemolymph suggested that a neurosecretory factor may modulate the normal neural control of calling behaviour.     

Female reproductive decisions and parasite burden in a calopterygid damselfly (Insecta: Odonata)

There is currently a gap in sexual selection theory about how much the environment drives female mating decisions. We present field data that suggest that female sexual behaviour in the damselfly Calopteryx haemorrhoidalis is influenced by parasite burden. Male wing pigmentation in Calopteryx is a sexually selected trait that signals a male's ability to cope with eugregarine parasites (an intestinal parasite that feeds on the adult's ingested food). Because adult C. haemorrhoidalis females also show wing pigmentation, we examined whether this trait is similarly influenced by parasite burden and whether it may signal the female's reproductive value. MaleC. haemorrhoidalis defend riverine substrates that females use for oviposition. After copulation and during oviposition, females are guarded by the copulating male against intruder males. Alternatively, females may avoid mating and ‘steal’ an oviposition site within a male's territory. In the present study, we found that the amount of female wing pigmentation was negatively correlated with the number of eugregarines present. Females with more parasites produced fewer eggs, survived fewer days, spent less time during courtship, ‘inspected’ fewer males before mating, had a lower mating success, were guarded for less time during oviposition and engaged in fewer ‘stealing’ events during oviposition. The reduced egg production and survival of heavily infected females may result from eugregarine depletion of the females' consumed food reserves. Thus, to offset reduced longevity, heavily infected females may accept a mating more rapidly and mate with fewer males. ‘Stealing’ behaviour may be related to the female's differential use of sperm from some males, particularly high-quality males. Interestingly, males that mated with low-pigmented females showed greater variance in wing pigmentation than did males that mated with high-pigmented females. Possibly, female wing pigmentation may signal a female's reproductive value, which provides females with longer mate-guarding episodes and reduced interference from intruder males. This study points out one possible constraint, intestine parasites, that females may face during mating decisions. Because females in bad condition mate with males in both good and bad condition, this constraint may be pervasive enough to weaken the intensity of selection for a male sexually selected trait, wing pigmentation, and help to maintain its variation in phenotypic expression. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Effect of multiple mating on the reproductive performance of the rice leaffolder moth,Cnaphalocrocis medinalis (Lepidoptera: Crambidae)

To clarify whether multiple mating of females and males affects the reproductive performance of the rice leaffolder moth, Cnaphalocrocis medinalis (Guenée), we examined the effect of the number of matings (once, twice, or three times) for females (female treatment) and males (male treatment) on the incidence of moth mating, number of eggs laid, egg hatchability, and adult longevity. We also compared the effect of multiple mating imposed on males or females separately with the effect of that imposed on both sexes simultaneously (both sexes treatment). The incidence of mating of females and males that mated three times (3-mated females and males) was significantly lower than for females and males that mated twice or once (2-mated or 1-mated females and males). The incidence of mating of 1-mated moths (both sexes) was significantly higher than for 2-mated or 3-mated moths (both sexes). Two-mated or 3-mated females laid significantly more eggs with significantly higher hatchability than 1-mated females. Females that mated with 1-mated males (second male mating) or 2-mated males (third male mating) laid significantly fewer eggs than those that mated with virgin males (first male mating). Females laid significantly more eggs after the second and third matings for moths of both sexes than after the first mating for moths of both sexes. The mechanisms of improvement and decline of female reproductive performance when multiple mating was imposed on males or females are also discussed in relation to the reproductive biology of C. medinalis.     

Sexual dimorphism of arrestment and gregariousness in the bed bug (Cimex lectularius) in response to cuticular extracts from nymphal exuviae

Releaser pheromones have direct behavioural effects to arrest, attract or disperse insects, whereas interactions within groups of social insects are often influenced by primer pheromones. The behaviour of insects displaying intermediate levels of sociality is largely unexplored in this context. In the present study, both the gregariousness and arrestment (settling near the odour source) of bed bugs Cimex lectularius L. (Hemiptera: Cimicidae) in response to conspecific exuvial extracts are described. Adult males are arrested on filter papers with extracts derived from exuviae of fifth‐instar nymphs. Adult females and nymphs display no significant evidence for such behaviour. Adults of both sexes show no preference for extracts of male versus female fifth‐instar exuviae. Arrestment of adult males does not occur on papers treated with fourth‐instar exuvial extracts. Because the insects are assayed behaviourally in groups, an index is calculated describing how far bugs are away from being located independently of one another, as a measure of gregariousness. Adult males have lower values for this index (i.e. locations are closer to independence). Adult females, nymph cohorts and mixed age groups all have higher values for this index, which tend to increase over time. Females exhibit a clear increasing dose‐dependent relationship for this index. It is concluded that the extracts of fifth‐instar nymphal exuvia arrest males on refuges that possess the odour source. However, gregariousness is induced in females, without evidence of a tendency to assemble near the odour source.     

Alternative mate-finding tactics in a non-territorial damselfly (Odonata: Coenagrionidae)

Males of the non-territorial damselfly Enallagma hageni have two alternative tactics for finding mates: (1) they search the banks of the pond for unmated females (searching tactic), or (2) wait at oviposition sites for females that resurface prematurely from underwater oviposition (waiting tactic). Although the searching tactic yielded more fertilizations than the waiting tactic, for time invested, the waiting tactic became increasingly successful later in the reproductive season due to changes in female oviposition behaviour. The two tactics can be maintained in the population because males can mate by the waiting tactic during the afternoon when few females are available to searchers. Among males visiting the breeding site an equal number of times, males mating by a mixture of tactics were as successful as males mating only by the main tactic. Because marked males were found to use both tactics, these behaviours are interpreted as evidence of behavioural plasticity within individuals, representing one conditional evolutionary strategy.     

Seminal fluid reduces female longevity and stimulates egg production and sperm trigger oviposition in a moth

Previous studies suggest that a number of factors in relation to mating may reduce female longevity and stimulate egg production and oviposition. However, it is still not clear whether these factors act on these parameters independently or in a collective way. Here we carried out a series of experiments including mating trials and seminal fluid injection to determine the factors responsible for reducing female longevity and stimulating egg production and oviposition in relation to mating in the moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). Results show that seminal fluid and sperm work collectively to allow females to achieve maximum realized fecundity (number of eggs laid) in E. kuehniella but these factors play different roles in the process and their actions are independent. Seminal fluid signals females to allocate resources to ova, resulting in shorter longevity and greater egg production while eupyrene (not apyrene) sperm in the spermatheca trigger females to lay maximum number of eggs. We suggest that the receptors for seminal fluid signal may be located in the female reproductive tract and haemolymph, and those for sperm signal may be in the spermatheca. Hypotheses that females prolong their longevity by oosorption, physical injuries by males reduce female longevity, and mechanical stimulation by males triggers oviposition, are not substantiated in the present study.     

Adaptive strategies of overwintering adults: Reproductive diapause and mating behavior in a grasshopper,Stenocatantops splendens (Orthoptera: Catantopidae)

Abstract To understand the adaptive strategies of the overwintering adults of Stenocatantops splendens, the mechanism of maintenance and termination of the reproductive diapause, the variation in mortality between overwintering females and males, and the mating strategy of the males were investigated. The results indicated that the adult reproductive diapause in natural conditions was mainly regulated by photoperiod in the fall – long photoperiods promoted reproductive development and short photoperiods maintained reproductive diapause, and the sensitivity of the overwintering adults to photoperiod was over before the end of the winter. When transferred from natural conditions to controlled laboratory conditions on dates from September through February, pre‐oviposition became increasingly shorter with increasingly deferred transfer dates regardless of photoperiod conditions. The adults treated with low temperature for 30 days in September through November had significantly shorter pre‐oviposition, suggesting that low temperatures in winter had an important role in the termination of reproductive diapause. The female had a significantly lower supercooling point than the male, which was related to their lower mortality after winter. In addition, observations of wild populations of the species indicated that mating behavior prior to winter and the duration of pre‐mating period were not affected by photoperiod; mating and sperm transfer were mostly completed by November. Compared with females only mating before winter, females mating in the spring had shorter life span, longer pre‐oviposition, lower hatching rate and laid fewer egg pods while showing no significant difference with regard to ovipositional interval, per pod number of eggs and nymph dry weight.     

Sexual selection in Woodhouse's toad (Bufo woodhousei) I. Chorus organization

I studied the reproductive behaviour of a population of prolonged-breeding Bufo woodhousei in central Arizona. Choruses formed in discrete and consistent areas of ponds, and males actively defended calling sites within these aggregations. Call rate and calling site residency, but not size, were important factors determining the outcome of male-male disputes within choruses. Females visited choruses to select males, and oviposition occurred away from the calling site of selected males. Natural and experimental observations revealed that females prefer males with a high call rate. Preliminary results indicated that large males did not achieve greater reproductive success, nor was there any suggestion of assortative mating in size of mated pairs. It is concluded that B. woodhousei has a lek mating system, possible because of its prolonged breeding period. These results are discussed in relation to other anuran mating systems and sexual selection in general.     

The influence of parthenogenesis-inducing Wolbachia on the oviposition behaviour and sex-specific developmental requirements of autoparasitoid wasps

Parthenogenesis-inducing (PI) Wolbachia are bacteria that cause incipient male eggs of parasitoid wasps to develop as females. These microbes may invade populations and lead to fixation of parthenogenesis. In this study, the consequences of fixation of PI Wolbachia on evolution of behaviour and development were addressed in three species of whitefly parasitoids in the genus Encarsia. Most sexual Encarsia are obligate autoparasitoids. In these haplodiploid wasps, fertilized, female-producing eggs are laid in whitefly or scale insect nymphs, while unfertilized, male-producing eggs are laid in immature parasitoids within the homopteran integument. The oviposition behaviour and progeny developmental requirements of unmated females of a sexual autoparasitoid species were compared with two species that were fixed for PI Wolbachia. All species were treated with antibiotics, effectively ‘curing’ the asexual species of Wolbachia infection. As expected, unmated females of the sexual species, E. pergandiella, laid few eggs in whiteflies relative to immature parasitoids, and males emerged exclusively from parasitoids. In contrast, females of one of the parthenogenetic species, E. formosa, laid few eggs in parasitoids relative to whiteflies, and male progeny emerged exclusively from whiteflies. Females of the second parthenogenetic species, E. hispida, were intermediate in their oviposition behaviour. Females laid eggs in both wasps and whiteflies. However, all of the males except one emerged from the whiteflies. The results suggest that the association of autoparasitoids and PI Wolbachia may result in dramatic evolutionary change of both host selection behaviour and developmental requirements of the infected wasps.     

Mating success and oviposition of a butterfly are not affected by non-lethal tissue sampling

Non-lethal methods of tissue sampling are increasingly used for genetic studies of insect species and the effects of this approach have long been assumed to be minimal. Tissue removal has the potential to influence insect reproductive behaviours such as mate recognition, courtship or oviposition but the effects of non-lethal sampling on reproductive success have not been widely and adequately tested. Here, we test potential effects of both wing-clipping and leg removal on reproductive behaviours of the cabbage white butterfly (Pieris rapae). We conducted a total of 93 male and 59 female mating trials, and found no significant differences in mating success between treated (i.e., tissue removed) and control individuals in either sex. We also monitored the number and location of eggs laid by 58 females. We found no significant differences in egg-laying behaviour among leg removed and control individuals. Power analysis indicated that we had sufficient statistical power to detect moderate effects of treatment on both mating and oviposition. Our study provides the most comprehensive examination to date of the effects of non-lethal sampling on reproductive behaviours in a butterfly/insect species, and supports the contention that tissue sampling is non-detrimental. To fully comprehend the general impacts of tissue sampling on butterfly reproductive behaviour however, additional similar studies need to be conducted on a variety of species with differing mating behaviours. Only through meta-analysis, may it be possible to detect more subtle effects of tissue removal which cannot be revealed within a single study due to sample size limitations.     

褐飞虱不同地理种群生物学特性的比较

在实验条件下比较了四个(龙州、九宫山、监利、新会)褐飞虱Nilaparvata lugens(Stal)地理种群的发育、繁殖、内禀增长能力等参数的异同。结果表明：1.北迁的迁入当代九宫山种群雌虫降落取食3.6d开始产卵,产卵量平均为522粒,低于其第二代居留型种群的714粒;2.四个种群在若虫l龄、5龄历期上有显著差异(a＝0.05).但决定翅型分化的2、3、4龄历期上无显著差异;成虫寿命、产卵历期无显著差异;新会种群产卵量高于其它三个种群;同龄期若虫的世代存活率,九宫山种群低于其它三个种群;综合反映发育、存活、繁殖等生命信息的内禀增长能力rm差异较小,在0.1874～0.1982间变化。本文还分析了产生上述异同的原因。