Effects of time-dependent intraspecific competition on offspring survival in the butterfly, Anthocharis scolymus (L.) (Lepidoptera: Pieridae)

Effects of mothers' eclosion and oviposition timing on the survival of their offspring in the pierid butterfly Anthocharis scolymus (L.) was examined. I recorded the performance of individual eggs and larvae that differed in their mother's eclosion and oviposition timing in a natural population, where A. scolymus feeds on Turritis glabra (L.) Bernh. Eggs laid early in the season, and larvae emerging from these eggs, had higher survival than eggs laid later, and larvae emerging from eggs that were laid later in the season, the causal factor being egg cannibalism by larvae on the same host plant. Logistic regression showed that females eclosing early in the season had higher offspring survival than females eclosing later. I conclude that optimal timing of adult eclosion in A. scolymus is a trade-off between eclosing early with associated higher offspring survival but lower egg-laying rate, and eclosing later with associated lower offspring survival but higher egg-laying rate. Received: 4 August 1997 / Accepted: 19 October 1997     

Possible Age-Dependent Variation in Egg-Loaded Host Selectivity of the Pierid Butterfly, Anthocharis scolymus (Lepidoptera: Pieridae): A Field Observation

To understand better the effects of age on host selection through conspecific egg detection by Anthocharis scolymus females, field observations were performed at a graveyard where the insect population was isolated and the host plant was limited to the cruciferous plant, Turritis glabra. We chased females and recorded their oviposition behaviors and the conditions of plants which females approached. Older females tended to avoid ovipositing on egg-loaded host plants and selectively laid eggs on nonloaded host plants. This result was not confounded by other factors such as seasonality, air temperature, plant height, plant phenological stage, surrounding vegetation, host plant density, and extent of plant damage. We discuss the possibility that females make an oviposition decision on how to lay their limited number of eggs during their remaining lifetime.     

The 'edgeeffect' in butterfly oviposition: causality in Anthocharis cardarnines and related species

Abstract. 1. An 'edge-effect', where outlying host plants receive proportionately most attention from insect herbivores, is described from the literature, and from data on Anthochoris cardamines (L.), in northern England.
2. Six hypotheses are examined as explanations for the effect in A.curdamines . Four are shown to be refuted by studies on female behaviour and the survival of larvae.
3. It is argued that the 'edge-effect' comes about due to two or more aspects of the searching behaviour of females. The effect may be seen as an outcome of behaviour adapted to searching for host plants of low density.     

A review of the pre-oviposition behaviour of small cabbage white butterfly, Pieris rapae(lepidoptera: Pieridae)

This paper reviews the literature concerning the ovipositional behaviour of Pieris rapae (small cabbage white butterfly) and where appropriate considers results from studies involving other butterflies. The paper considers searching behaviour, stimuli utilised in host plant finding and identification and concludes with a general section on the role of learning and prior experience in ovipositional behaviour.     

Host plant-based territoriality in the white peacock butterfly,Anartia jatrophae (Lepidoptera: Nymphalidae)

Mate locating behavior of Anartia jatrophaewas studied near Ochopee, Collier County, Florida. Males were individually marked, and focal animal samples were used to determine activity, residency, and interactions with other butterflies. We recaptured more than half of 53 marked males within the study area on subsequent days. Marked males restricted non-feeding activity to roughly circular areas typically less than 15 m in diameter. Males showed considerable site fidelity and chased both conspecifics and a variety of other insects. Typically, encountered individuals flew away, and the resident peacock male returned to perch near his previous perch. Encounters with conspecific males averaged 38 sec, three times longer than with other insects. Such site fidelity combined with aggressive interactions indicates territorial behavior. When male density more than doubled, site fidelity decreased, resident turnover increased, and areas that had not been defended at lower density were defended. Without exception, defended sites contained the larval host, Bacopa monnieri.In butterfly mating systems, defense of host plants appears to be much less common than defense of natural features such as landmarks.     

Effects of plant odor on oviposition by the black swallowtail butterfly,Papilio polyxenes (Lepidoptera: Papilionidae)

Black swallowtail females laid more eggs on plant models treated with contact stimulants and volatiles from carrot leaves than on models treated only with contact stimulants. The volatiles enhanced landing rates and females alighted more frequently on artificial leaves treated with host volatiles than on adjacent control leaves. Volatiles from cabbage, a nonhost, inhibited landing rates on artificial leaves treated with carrot contact stimulants. Examination of antennae revealed two major types of sensilla, believed to be olfactory in function. Electroantennogram preparations responded more strongly to carrot volatiles than to cabbage volatiles and several shared responses at particular retention times to carrot volatile components eluting from a gas chromatograph. Our results are consistent with a long-standing hypothesis that behavioral responses to essential oil components characteristic of the larval food plants have facilitated host shifts in the genus Papilio.     

Effect of host deprivation on egg quality,egg load,and oviposition in a solitary parasitoid,Chetogena edwardsii (Diptera: Tachinidae)

Solitary parasitoids are limited to laying one egg per host because larvae compete within hosts. If host encounter rate is low, females should not increase the number of eggs/host in response. The tachinid fly, Chetogena edwardsii,was used to evaluate the effect of host deprivation on egg accumulation, oviposition behavior, and egg quality in a solitary parasitoid. Females deprived of hosts for 2– 7 days accumulate about 1 day's supply of eggs. Egg output of deprived females once hosts are restored does not differ from that of control females. Deprived females retain one egg in the uterus where it undergoes embryogenesis. Maggots emerging from retained eggs are more likely to survive in hosts molting in 40 h or less after receipt of an egg than are maggots emerging from eggs fertilized shortly before oviposition. Egg retention is a consequence of host deprivation that permits females to broaden the range of hosts they can exploit to include soon-to-molt hosts and possibly multiply parasitized hosts.     

The distribution of eggs per host in a herbivorous insect--intersection of oviposition, dispersal and population dynamics

1. The dynamics of parasitic organisms depend critically upon the frequency distribution of parasite individuals per host. However, the processes giving rise to this frequency distribution have rarely been modelled and tested for organisms with complex host selection behaviour. 2. In this study Microrhopala vittata, a chrysomelid beetle, was used to investigate how oviposition behaviour, movement and density of host plants interact in shaping the frequency distribution of egg clusters per host in the field. 3. Enclosures were stocked with two different host species and different beetle densities and various stochastic process models were fitted to egg cluster count data obtained from these enclosures. The different models were derived considering different scenarios, in particular whether or not plant density limits oviposition rate, whether or not ovipositing females actively seek out the most attractive plant within their perception radius and whether a female's oviposition rate is determined by plant intrinsic factors, the plant's egg cluster load or the surrounding beetle density. 4. The model parameters fitted to cage data were used to describe the frequency distribution of egg cluster counts obtained in a release experiment in the field. A total of 220 beetle pairs were released at five locations in a field where this beetle was not observed previously. Each release point was at a border between the two host species. 5. One model predicted for the preferred host species the egg cluster count frequencies in the field from parameters estimated in the cages. This model assumed that egg clusters present on a plant increased subsequent oviposition on this plant. All other models could not describe the distribution of egg cluster counts for either of the two host species. 6. The results suggest that females seek out attractive hosts actively and the attractiveness of a plant increases with its egg cluster load. This behaviour creates a frequency distribution of egg clusters per host that depends only on beetle density but not on plant density. This conclusion has important implications for modelling insect-plant interactions.     

Age- and density-related oviposition behavior of the European corn borer,Ostrinia nubilalis (Lepidoptera: Pyralidae)

Age-related oviposition patterns ofOstrinia nubilalis were studied at three population densities in the laboratory by releasing newly eclosed adults in wire-screened cages and analyzing their oviposition throughout the adult stage with digital analysis. Oviposition sequences of individual females depositing egg masses were documented on the third and seventh nights after eclosion with a video camcorder. During a sequence, a female produced an egg in an average time of 15 or 26 s on the third and seventh nights, respectively, and completed depositing an egg mass the size of 20–39 eggs in an average time of 316 and 525 s, respectively. Females were not easily disturbed during egg mass deposition and pulsated their abdomen before deposition of each egg. Females produced few egg masses the first night after eclosion. Oviposition increased on nights 2 and 3 but declined steadily thereafter as females matured. Females older than 6 nights produced fewer egg masses; the proportion of egg masses with fewer than 20 eggs increased gradually. By the end of the adults' lifetime, nearly 100% of the egg masses had fewer than 20 eggs. The data are fundamental to our research to define the role of phytochemicals in modifying oviposition behavior of the European corn borer.     

Strategic sperm allocation in the Small White butterfly Pieris rapae (Lepidoptera: Pieridae)

1. In species where females mate multiply, it is important for males to recuperate quickly in order to maximize their fertilization success. Butterflies produce a spermatophore at mating containing accessory secretions and sperm of two types: a large number of non-fertile 'apyrene' sperm and fewer fertile 'eupyrene' sperm. Many butterfly species eclose with most nutrients for reproduction already present. Males must therefore decide how to allocate resources to the various spermatophore components at any given mating.
2. Recovery rates of apyrene and eupyrene sperm number and spermatophore size was studied in the polyandrous Small White butterfly Pieris rapae . The mass of the first spermatophore increases with time since eclosion, as does the number of both types of sperm. Similarly, on a male's second mating, both the mass of the spermatophore and the number of sperm increases with time since the first mating.
3. However, the rate of increase in eupyrene sperm numbers is higher after the first mating. The difference in rate of increase may be the result of different probabilities of virgin and non-virgin males obtaining future matings.
4. Males have a sperm storage organ, the duplex, in which they retain sperm after their first mating. This ensures that high sperm numbers are available for their second mating, even when remating only 1 h later. Thus, males do not ejaculate all available sperm on any given mating, and seem to have different strategies on their first and second matings.
5. It can be argued that Small White butterfly males allocate sperm strategically according to the probability of obtaining subsequent matings, and the level of sperm competition.     

Host plant relationships of an endangered butterfly, Lopinga achine (Lepidoptera: Nymphalidae) in northern Europe

The aim of the present study was to evaluate—in a geographic perspective—the role of host plant as a determinant of habitat quality for Lopinga achine, a satyrine butterfly endangered over much of its European range. Laboratory trials were performed to record host choices made by the ovipositing females as well as by neonate larvae. In rearing experiments, growth performance and mortality on different host plants was determined. Oviposition was found to be indiscriminate but larvae were shown to be able to choose between host plants, with the choices made broadly consistent with growth performance of the larvae on particular hosts. Nevertheless, most grasses and sedges offered were found to support larval development reasonably well. No clear superiority of the previously suggested primary host plant Carex montana could be shown. Importantly, no differences in host plant relationships were found between the populations of Sweden, western Estonia and eastern Estonia. In particular, the larvae originating from eastern Estonian populations developed on C. montana equally well even if the plant is absent from their native habitat. In the context of species conservation, one should conclude that L. achine is polyphagous enough on various grasses and sedges so that the presence of any particular host species cannot be a critical component of habitat quality. Nevertheless, some preference to broad- and soft-leaved hosts, as well as sensitivity to host wilting, may partly explain the butterfly’s preference to moist forest habitats, further emphasizing the central role of habitat management in the conservation practice of this species. In turn, the absence of ecological differences between geographic populations should enable conservationists to successful transfer their experience across national boundaries.     

Refrigeration of Riptortus clavatus (Hemiptera: Alydidae) eggs for the parasitization by Gryon japonicum (Hymenoptera: Scelionidae)

Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae) is a solitary egg parasitoid of Riptortus clavatus (Thunberg) (Hemiptera: Alydidae) one of the most important pests in soybean in Korean and Japan. Refrigeration of R. clavatus eggs for up to 120 days was evaluated as a method of mass production of G. japonicum. The refrigeration reduced the eclosion of eggs, thus no nymph emerged after 30 days of egg refrigeration. Increased duration of host acceptance behaviors by G. japonicum and some detrimental effects on parasitism rate, developmental time, longevity, and adult size of the parasitoid were found in refrigerated host eggs. However, all the biological parameters of G. japonicum were unaffected by the refrigeration of up to 30 days. Gryon japonicum parasitized 16 and 14 host eggs daily that were refrigerated for 15 and 30 days, respectively, which did not differ from parasitization of fresh host eggs. Furthermore, refrigeration of host eggs did not reduce the reproduction of the emerged adult parasitoids and emergence and sex ratio of their progeny. Gryon japonicum also parasitized 14 and 13 refrigerated host eggs per day kept at 26.3°C and 78.7% RH for 2 and 4 days of post-refrigeration without significant reduction, respectively. These results show that refrigeration of R. clavatus eggs can be a good method for mass rearing of the parasitoid, and the host eggs killed by cold storage can be supplemented in the field to boost field parasitism.     

Host plant utilization by butterfly larvae in the Andaman and Nicobar Islands (Indian Ocean)

The larval food plants of the butterflies of the Andaman and Nicobar islands have not been studied, although the butterfly fauna per se is fairly well known. For the first time we report the food plants of the larvae of 120 species of butterflies from these islands on the basis of laboratory rearing and field studies. This information is essential for the formulation of management programmes for butterfly conservation on these islands which are known to harbour critical swallowtail and (possibly) danaine faunas.     

Changes in egg colour, egg weight and oviposition rate with the number of eggs laid by wild females of the small heath butterfly, Coenonympha pamphilus

ABSTRACT. 1. The colour of eggs laid by individual Coenonympha pamphilus (L.) (Lep., Satyridae) females changed over their lifespan. The first laid eggs were green, but after having laid about 100 eggs, females laid only yellow eggs.
2. By following females in the field, or by capturing wild females, and noting the colour of their eggs, it was established that younger females showed higher oviposition rates and laid heavier eggs than older females.
3. Hence, wild C.pamphilus females are unable to sustain a constant egg production by extracting amino acids or any other nutrients from nectar. We hypothesize that this is a general phenomenon in nectar feeding butterflies.
4. The egg colour did not seem to match the colour of the substrate on which the female chose to deposit the egg.     

Oviposition site selection by the diamondback moth,Plutella xylostella (L.) (Lepidoptera: Plutellidae)

AlthoughPlutella xylostella (L.) is a worldwide pest of cruciferous crops, relatively little is known about its oviposition behaviour. This study was undertaken to provide necessary information about mechanisms involved inP. xylostella host selection. Four oviposition behaviours were described. Moths were given artificial substrates treated with water, sinigrin, orBrassica napus (cv. Westar) squashes, combined withB. napus volatiles and/or grooves in the substrate. No eggs were deposited in the absence of olfactory and gustatory stimuli. Moths given gustatory but not olfactory stimuli deposited similar numbers of eggs but spent significantly more time performing olfactory-related behaviours. Conversely, moths given olfactory but not gustatory stimuli did not oviposit.SSubstrate grooves did not influence egg numbers but appeared to influence egg location. The order in which oviposition behaviours occurs and the relative importance of stimuli type are discussed.     

Diapause termination in two species of tropical butterfly, Euploea core (Cramer) and Euploea sylvester (Fabricius) (Lepidoptera: Nymphalidae)

Abstract This study examined the factors used as cues for diapause termination by two Euploea species. Euploea core and E. sylvester were collected from two overwintering sites at Chillagoe, Queensland. Under tropical wet-season conditions, more butterflies terminated diapause (approximately 60%) than those kept under dry-season conditions (approximately 40%). However, 100% diapause termination occurred only when butterflies were kept under wet-season conditions and were fed with honey. For reproductive success, Euploea species need to terminate diapause rapidly to synchronise oviposition with fresh, rapid growth of their larval host plants, which often occurs after rain. The presence of rainfall, increased temperature and long days alone is not a fail-safe set of cues for this event. Our results suggest that food (as nectar), in conjunction with these combined environmental factors, provide Euploea species with a reliable signal that larval host resources are available for oviposition.     

Studies on the toxicity of insecticidal drift to the first instar larvae of the Large White butterfly Pieris brassicae (Lepidoptera: Pieridae)

The toxicity (LD,) of eight insecticides to 2–day-old first instar larvae of Pieris brassicue was determined by topical application. On this basis, the insecticides could be ranked in ascending order viz. dimethoate > pirimicarb > phosalone > endosulfan > fenitrothion > pirimiphos-methyl > fenvalerate > diflubenzuron. Relative to endosulfan, dimethoate and pirimicarb were 30–25 times less toxic while at the other extreme, fenvalerate (x 12) and diflubenzuron (x 26) were much more toxic to the larvae of P. brassicae. A methodology was developed for examining the effects of spray drift through bioassay using these 2–day-old larvae. Six field trials with commercial formulations were carried out in which variables other than the insecticide and wind speed were held constant as far as possible. Phosalone (700 g active ingredient ha) produced no effect beyond 1 m downwind at low wind speed (2 m s); at high wind speed (4 m s-¹). larval mortality (5.3%) was recorded up to 2m. Fenitrothion (1050 g a.i. ha^-1) at moderate wind speed (3 m s-^l) caused mortality up to 4 m while fenvalerate (30 g a.i. ha-^l) at the same wind speed affected larvae up to a distance of 8 m. Diflubenzuron at a very low dosage (6.5 g a.i. ha-¹) also produced effects up to 8 m. At the maximum approved dosage (100 g a.i. ha^-1), and at high wind speed (4.25 m s-^l), diflubenzuron killed 8.4% of the larvae at 16 m distance. At wind speeds of 2 - 3.5 m s^-1, spray deposits on the upper surfaces of water sensitive papers were high at 0 m and declined exponentially with distance. At higher wind speeds (4 - 4.25 m s^-I) turbulence produced irregular deposits. Deposition on lower surfaces was much lower than on upper surfaces but the trends with distance and wind speed were the same. The exponential relationships between mortality and distance, and drift deposition and distance, were examined. The results are discussed with respect to laboratory toxicities, application rates, wind speeds and ecological factors.     

BAC selection of the large white butterfly,Pieris brassicae (Lepidoptera: Pieridae) containing orthologs of the silkworm,Bombyx mori (Lepidoptera: Bombycidae)

Applied Entomology and Zoology - We constructed a bacterial artificial chromosome (BAC) library from the large white butterfly, Pieris brassicae (L.) (Lepidoptera: Pieridae), which...