Population genetics of Eldana saccharina Walker (Lepidoptera: Pyralidae) and the implications for management using biocontrol

The African sugarcane stalk borer, Eldona saccharina Walker (Lepidoptera: Pyralidae), is widely distributed throughout sub-Saharan Africa and is an important insect pest of maize and sugarcane. The insect shows significant variation in behaviour, host plant and natural enemy guild in different regions. Several attempts to redistribute the natural enemies of E. saccharina from West Africa to South Africa were unsuccessful. The significant behavioural, host plant and natural enemy variations as well as failures of biocontrol attempts evoked a hypothesis of genetic diversification. To evaluate this hypothesis a molecular analysis was conducted on geographically isolated populations of E. saccharina from East, North, South and West Africa, using the cytochrome c oxidase subunit I (COI) region of the mitochondrial genome. The results revealed that E. saccharina populations are separated into four major units corresponding to the West Africa, Rift Valley, South/East Africa and southern African populations. Mitochondrial DNA divergence among the four populations ranged from 1% to 4.98%. To examine the impact of the observed genetic variation on the fertility of inter-population crosses, a mating experiment was conducted between the Rift valley and South African population to produce an F1 generation, and these were backcrossed with the South African parent population. Fertility of eggs produced by the F1/parent population cross was significantly reduced when compared to fertility of the "true" South African line, and the F1/F1 cross. The contributions of the observed genetic differences and inter population incompatibility for the failure of previous biocontrol attempts are discussed and recommendations on future biocontrol practices are given.     

Diversity and abundance of lepidopteran stem borers and their host plants in Ethiopia

Lepidopteran stem borers are among the most important insect pests of maize, sorghum and sugarcane in sub‐Saharan Africa. Except for Chilo partellus, the other stem borer pests in Ethiopia are indigenous to Africa and are assumed to have coevolved with some native grasses and sedges in the natural habitat. In addition to pest species, natural habitats harbour diverse non‐economic stem borer species, some of which are new to science. However, with the growing threats to natural habitats, some non‐economic stem borer species may switch or expand their host ranges to include cultivated crops and evolve as “new” pests. Besides host switch, some of the unknown species currently limited to natural habitats may disappear. We examined the diversity, abundance and interactions of lepidopteran stem borers and their wild host plants in five different vegetation mosaics in Ethiopia. The stem borer species diversity varied among vegetation mosaics and host plants. Forty‐four stem borer species belonging to 14 different genera in the families of Noctuidae, Crambidae, Pyralidae and Tortricidae were recorded from 34 wild host plants and through light trap. Among these families, Noctuidae was the highest in species richness in which 31 species were identified, out of which 15 species and two genera were new to science. This paper discusses the ecological interpretation of host plant–stem borer species interactions, particularly in relation to habitat disturbances.     

Water stress augments silicon-mediated resistance of susceptible sugarcane cultivars to the stalk borer Eldana saccharina (Lepidoptera: Pyralidae)

Silicon (Si) can improve resistance of plants to insect attack and may also enhance tolerance of water stress. This study tested if Si-mediated host plant resistance to insect attack was augmented by water stress. Four sugarcane cultivars, two resistant (N21, N33) and two susceptible (N26, N11) to Eldana saccharina Walker were grown in a pot trial in Si-deficient river sand, with (Si+) and without (Si-) calcium silicate. To induce water stress, irrigation to half the trial was reduced after 8.5 months. The trial was artificially infested with E. saccharina eggs after water reduction and harvested 66 days later. Silicon treated, stressed and non-stressed plants of the same cultivar did not differ appreciably in Si content. Decreases in numbers of borers recovered and stalk damage were not associated with comparable increases in rind hardness in Si+ cane, particularly in water-stressed susceptible cultivars. Overall, Si+ plants displayed increased resistance to E. saccharina attack compared with Si- plants. Borer recoveries were significantly lower in stressed Si+ cane compared with either stressed Si- or non-stressed Si- and Si+ cane. Generally, fewer borers were recovered from resistant cultivars than susceptible cultivars. Stalk damage was significantly lower in Si+ cane than in Si- cane, for N21, N11 and N26. Stalk damage was significantly less in Si+ combined susceptible cultivars than in Si- combined susceptible cultivars under non-stressed and especially stressed conditions. In general, the reduction in borer numbers and stalk damage in Si+ plants was greater for water-stressed cane than non-stressed cane, particularly for susceptible sugarcane cultivars. The hypothesis that Si affords greater protection against E. saccharina borer attack in water-stressed sugarcane than in non-stressed cane and that this benefit is greatly enhanced in susceptible cultivars is supported. A possible active role for soluble Si in defence against E. saccharina is proposed.     

Influence of plant silicon and sugarcane cultivar on mandibular wear in the stalk borer Eldana saccharina

1 Silicon can increase the resistance of plants to attack by herbivorous insects. The present study aimed to determine the effect of silicon and cultivar on mandibular wear in larvae of the sugarcane stalk borer Eldana saccharina Walker (Lepidoptera: Pyralidae).
2 Four sugarcane cultivars, resistant (N21, N33) and susceptible (N11, N26) to E. saccharina were grown in a pot trial in silicon deficient river sand, with (Si+) and without (Si−) calcium silicate. Individual third-instar larvae were confined on the sugarcane stalk at three known feeding sites (leaf bud, root band and internode) and left to feed for 21 days.
3  Eldana saccharina larval heads were mounted on stubs, with the mandibles oriented horizontally and photographed under a scanning electron microscope. Mandibular wear was measured from the digital images using a quantitative method.
4 Although there was a trend for increased wear in larvae that developed on Si+ cane, no significant effect of silicon, cultivar or site on mandibular wear of E. saccharina was shown.
5 This is the first study to accurately and quantitatively measure the mandibular wear of an insect fed on Si+ plants.     

Interactions between Fusarium species from sugarcane and the stalk borer, Eldana saccharina (Lepidoptera: Pyralidae)

In this study, beneficial relationships between Fusarium species in sugarcane and the stalk borer, Eldana saccharina (Lepidoptera: Pyralidae) were demonstrated in vitro . In addition, Fusarium species with antagonistic properties were found to inhabit sugarcane. Attenuated Fusarium isolates from sugarcane stalks collected across the South African sugar industry were incorporated into diet formulated to mass rear E. saccharina . Of the over 200 Fusarium isolates obtained, 10 that significantly improved the survival and development of E. saccharina larvae and considered to be beneficial were selected for further study, as were 10 that were detrimental or antagonistic to the stalk borer. Twelve of the selected isolates were identified as F. sacchari by direct sequencing of translation elongation factor-1α fragments, eight of which resulted in reduced numbers of surviving larvae and significantly lower larval masses. F. proliferatum isolates resulted in increased survival and mass of E. saccharina and three of the five isolates assigned to the F. pseudonygamai group enhanced E. saccharina development. Results from olfactory choice experiments suggested the production of attractive and repellent metabolites by certain isolates. Findings from this study may offer additional or alternative strategies for managing E. saccharina infestation of sugarcane.     

Bt-maize as a potential trap crop for management of Eldana saccharina Walker (Lep., Pyralidae) in sugarcane

Abstract:  Notwithstanding the introduction of several pest management tactics, the stalk borer Eldana saccharina Walker (Lep., Pyralidae) remains the most serious pest in South African sugarcane. A novel tactic for managing this pest in sugarcane would be the use of a dead-end trap crop that attracts moths for oviposition and curtails subsequent larval development, thereby reducing pest population size. Glasshouse bioassays, in which moths chose to oviposit on maize producing Bacillus thuringiensis Cry1Ab toxin ( Bt -maize), non- Bt -maize or sugarcane of two cultivars (borer-resistant and -susceptible), showed that E. saccharina laid significantly more eggs and egg batches per dry leaf and unit mass of dry leaf on maize ( Bt or non- Bt ) than on either of the cane cultivars. When moths had a choice of ovipositing on 2-, 3-, 4- or 5-month-old maize ( Bt and non- Bt ), dry leaf number and mass of dry leaf material was significantly correlated with number of eggs and egg batches, indicating that older plants, which carried larger amounts of dry leaf matter, were more attractive for oviposition. Finally, glasshouse assays in which hatching larvae fed on 2.5-, 3.5- and 4.5-month-old Bt and non- Bt -maize plants, showed that the Cry1Ab toxin was effective in killing E. saccharina larvae in all Bt -maize plant growth stages, confirming that Bt -maize fulfilled the third requirement (curtailing larval development) of a dead-end trap crop for this pest. We argue that Bt -maize warrants further testing in the field as a trap crop, both alone and as a component of a 'push–pull' or habitat management system for E. saccharina in sugarcane.     

A recently acquired host plant provides an oligophagous insect herbivore with enemy-free space

Enemy-free space (EFS) is a potentially important factor affecting host plant use by phytophagous insects. Yet only a few field studies have demonstrated that natural enemy activity is the sole mechanism underlying use of novel host plants by herbivorous insects. This may be due to the fact that in earlier studies, both herbivores and natural enemies had the opportunity to adapt to the new host plant. Here we studied the possibility that EFS underlies the recently recorded increase in Phthorimaea operculella densities on tomato plants in a few areas within its geographical range. Through field experiments in Ethiopia, we show that all three conditions proposed by Berdegue et al. to demonstrate EFS are fulfilled. First, a significantly higher proportion of larvae survive on caged than on exposed potato plants, showing that natural enemies are an important mortality factor on the original host, potato. Second, larval survival was significantly higher on exposed tomato than potato plants, implying greater protection for the herbivore from its natural enemies on tomato than on potato plants. Thus tomato plants provide P. operculella with an EFS. Finally, larval survival was significantly higher on caged potato than on caged tomato plants at the preblossom stage, indicating that, in the absence of natural enemies, there is a fitness cost when larvae feed on the sub-optimal tomato plants. Fulfillment of this third condition points to the importance of natural enemy activity relative to that of other unidentified factors, such as food quality and competition. An intensive field survey provides further support for this conclusion.     

Silicon impedes stalk penetration by the borer Eldana saccharina in sugarcane

Many plants grown in soils amended with silicon (Si) display increased levels of resistance to attack by insect herbivores. This study aimed to determine if Si treatment impeded Eldana saccharina Walker (Lepidoptera: Pyralidae) stalk penetration and subsequent damage, as well as borer mass gain, on the node and internode of a susceptible (N11) and a resistant (N33) sugarcane cultivar. Sugarcane [Saccharum spp. (Poaceae)] cultivars were grown in a pot trial in Si‐deficient river sand, with (Si+) and without (Si–) calcium silicate. Sugarcane was infested with 2‐week‐old E. saccharina larvae and harvested at four times, 24, 48, 72, and 96 h after infestation. Silicon‐treated plants showed significant increases in Si content compared to controls, and the external rind was significantly harder for Si+ cane than Si– cane. Silicon treatment significantly decreased borer penetration, stalk damage, and larval mass gain. The results are consistent with the hypothesis that Si contributes to sugarcane stalk borer resistance by impeding larval penetration. Silicon appears to contribute to the suppression of E. saccharina directly through reduced larval growth and feeding damage to the crop, and indirectly by delaying stalk penetration, resulting most likely in increased exposure time of young larvae to natural enemies, adverse climatic factors, or control measures that target young larvae (e.g., insecticides).     

Active defence of herbivorous hosts against parasitism: Adult parasitoid mortality risk involved in attacking a concealed stemboring host

Phytophagous insects have several defence strategies to defend themselves against attack by parasitic wasps. Larval lepidopteran hosts can defend themselves actively to prevent oviposition by the parasitoid. Among the aggressive kinds of behaviour exhibited by hosts against parasitoids are violent wriggling, biting and spitting. The behaviour of the braconid parasitoid Cotesia sesamiae attacking stemboring larvae inside their feeding tunnel in the plant stem was investigated in maize and sugarcane stem pieces and transparent artificial tunnels. Attacking a defending stemborer host inside the confined space of a tunnel was shown to be risky for the female parasitoid. A considerable proportion (25%) of female wasps were killed in their attempt to attack the spitting and biting host. No difference was found in the behaviour of C. sesamiae attacking the suitable host Sesamia calamistis or the unsuitable host Eldana saccharina. The consequences of this high mortality risk involved in each host attack is discussed in relation to the ecology of the parasitoid.     

Long-term seasonal fluctuations of lepidopteran cereal stemborers and their natural enemies on maize and wild host plants in southern Benin

Abstract  The seasonal fluctuation of lepidopteran cereal stemborers on maize and wild host plants (i.e., grasses and a few sedges) was investigated in southern Benin from 1988 to 1998 by time series analysis and repeated-measures analysis of variance (ANOVA). In addition, a walk-in light trap was used to study the flight behavior of adult moths. On both cereals and grasses, the noctuid Sesamia calamistis was the predominant species, followed by the pyralid Eldana saccharina . The noctuid Busseola fusca was rare on both maize and wild host plants. In general, pest populations increased during the course of the year to reach peak densities during the second short rainy season, and then crashed to close to zero during the dry season. On wild host plants, egg masses and other immature stages were collected throughout the year but they were higher on wild grasses than maize during the off-season. Thus wild host plants can be considered as refuge for both borers and natural enemies during the off-season, when maize is not available. However, only four out of the eleven wild host species played a discernable role. S. calamistis egg densities appeared to be influenced by density-dependent factors, suggesting an effect of natural enemies. Temperature and rainfall had a negative effect on egg abundance. Larval parasitism by a Kenyan strain of the braconid Cotesia sesamiae , which was released in southern Benin in the early 1990s, and by the tachinid Sturmiopsis parasitica varied between seasons and years but there were no discernable patterns. For both parasitoids and borer host species, parasitism was positively correlated with trap catches of adult moths. The recovery of C. sesamiae during a 2-year period suggests that the parasitoid has established its population in southern Benin.     

Host growth form underlies enemy-free space for lichen-feeding moth larvae

1.?Natural enemies may direct the host use of herbivorous insects on those hosts that ensure highest survival, thus creating enemy-free space. Host structure may contribute to enemy-free space if the current host ensures better refuge from natural enemies than other potential hosts. So far, however, direct evidence of the role of host structure for enemy-free space is lacking. 2.?This study looks at the effect of physical host structure on the previously demonstrated enemy-free space of a lichen-feeding moth, Cleorodes lichenaria by manipulating the structure of host lichens and the access of natural enemies to larvae in the field. It was predicted that if larvae receive enemy-free space on Ramalina lichens because of their shrubby appearance, larvae should survive better on shrubby than on flat lichens in the presence of natural enemies but not in the absence of natural enemies. 3.?Larvae survived better on shrubby than flat lichens and when the access of natural enemies to larvae was prevented than in the presence of them. According to the prediction, larvae in the presence of natural enemies survived better on shrubby compared with flat thalli but not in the absence of natural enemies. Thus, shrubby host structure promotes survival of larvae and underlies the enemy-free space on Ramalina species in natural conditions. 4.?Host structure as a mechanism for enemy-free space and the direct impact of host structure for the performance of C.?lichenaria larvae are discussed. Other potential reasons, such as lichen secondary chemicals and host-induced colouration of larvae as a basis of enemy-free space, are also discussed.     

Predicting the outcomes of a tri‐trophic interaction between an indigenous parasitoid and an exotic herbivorous pest and its host plants

Understanding the novel ecological interactions that result from biological invasions is a critical issue in modern ecology and evolution as well as pest management. Introduced herbivorous insects may interact with native plants and indigenous natural enemies, creating novel tri‐trophic interactions. To help predict the potential outcomes of novel interactions, we investigated the behavioural and physiological responses of an indigenous generalist parasitoid (Habrobracon gelechiae) to an introduced generalist herbivore (the light brown apple moth, Epiphyas postvittana) and its new host plants in California. We first examined the parasitoid's host location and acceptance on a range of nine common host plants of the moth representing distinctly different geographic origins and morphologies (to examine the effect of a known toxic plant on the parasitoid's performance, an additional toxic plant species was also tested that the moth consumes in the laboratory but does not naturally attack). The parasitoid was able to locate the host larvae on all plants equally well, although clutch size was affected by host plant. We then determined fitness of the moth and the parasitoid on four representative plants. The moth larvae suffered higher mortality and a slower developmental rate on the known toxic plant than on the other three plants, but the parasitoid's fitness correlates did not differ between the host food plants. These results show a high level of plasticity in the indigenous generalist parasitoid in its ability to exploit the exotic host on a wide range of host plants, generating an invasion‐driven novel tri‐trophic interaction.     

Parasitoids follow herbivorous insects to a novel host plant,generalist predators less so

The ‘enemy‐free space’ hypothesis predicts that herbivorous insects can escape their natural enemies by switching to a novel host plant, with consequences for the evolution of host plant specialisation. However, if natural enemies follow herbivores to their novel host plants, enemy‐free space may only be temporary. We tested this by studying the colonisation of the introduced tree Eucalyptus grandis (Hill) Maiden (Myrtaceae) by insects in Brazil, where various species of herbivores have added eucalyptus to their host plant range, which consists of native myrtaceous species such as guava. Some herbivores, for example, Thyrinteina leucoceraea Ringe (Lepidoptera: Geometridae), cause outbreaks in eucalyptus plantations but not on guava, possibly because eucalyptus offers enemy‐free space. We sampled herbivores (mainly Lepidoptera species) and natural enemies on eucalyptus and guava and assessed parasitism of Lepidoptera larvae on both host plant species during ca. 2 years. Overall, predators were encountered more frequently on guava than on eucalyptus. In contrast, parasitoids were encountered equally and parasitism rates of Lepidoptera larvae were similar on both host plants. This indicates that herbivores may escape some enemies by moving to a novel host plant. However, this escape may be temporary and may vary with time. We argue that studying temporal and spatial patterns of enemy‐free space and the response of natural enemies to host use changes of their herbivorous prey is essential for understanding the role of natural enemies in the evolution of host plant use by herbivorous arthropods.     

Study on some bioecological aspects of Eldana saccharina Walker (Lep., Pyralidae) on Zea mays L. and alternative host plants

Abstract:  In an attempt to set up habitat management strategy against Eldana saccharina Walker, an economically important graminaceous stem and cob borer, two laboratory experiments were carried out. The first experiment was designed to assess oviposition preference of E. saccharina for growth stages, plant parts and freshness of different host plants and between host plants species. Zea mays L., Sorghum arundinaceum (Desv.) Stapf, Andropogon gayanus Kunth, Panicum maximum Jacq., Pennisetum polystachion (Linn.) and Cyperus papyrus L. were assessed. Results showed that E. saccharina preferred wild grasses to maize for oviposition. More than 94% eggs were laid on wild grasses. Of all tested grasses, P. polystachion was the most attractive with more than 30% of collected eggs. For all plant species, post-tasseling stage was more attractive than the tasseling and pre-tasseling ones. More than 90% of total eggs were laid on dry leaves and sheaths and less than 10% on fresh leaves. Different characteristics relating to population dynamics of E. saccharina were assessed in the second experiment. Larval survival rate was 10% on Z. mays , 0.50% on S. arundinaceum and around 0% on the other wild grasses. Larval development length was longer on S. arundinaceum than on Z. mays . Females reared on Z. mays were three times more fecund than those reared on S. arundinaceum . Complete life table of females from larvae reared on Z. mays was studied.     

Indigenous Natural Enemies Associated with Phyllocnistis citrella (Lepidoptera: Gracillariidae) in Eastern Spain

The incidence of generalist indigenous natural enemies of the citrus leafminer (CLM), Phyllocnistis citrella Stainton (Lepidoptera; Gracillariidae), was monitored during three growing seasons at two different orchards located in the major citrus-growing area of Spain. Composition of the parasitoid complex changed during the study period. However, the eulophids Cirrospilus near lyncus Walker and Pnigalio pectinicornis L. were consistently the predominant species. Despite the varying composition of the parasitoid complex, oviposition, host feeding, and predatory preferences of the natural enemies of the CLM clearly centered on third instar larvae. Incidence of beneficial fauna increased as the season progressed, reaching maximal values up to 70% of susceptible leafminers (mature larvae) at the end of the summer. Parasitism was significantly related to relative host density. However, predation showed no relationship to host availability but did so to flushing in one of the orchards. Incidence of indigenous natural enemies of the CLM should not be ignored when planning any introduction of exotic parasitoids, and their conservation should be taken into account when planning any citrus IPM strategy.     

Record of Eldana saccharina Walker (Lep,Pyralidae) in inland South Africa and its genetic relationship with the coastal population

Surveys to investigate the distribution and abundance of stem borers in natural habitats were conducted in February 2006 and January–February 2007. The surveys included eastern, northern and central parts of South Africa as well as three localities in Lesotho. During the surveys, Eldana saccharina Walker was recovered from three new localities in inland South Africa and two new indigenous hosts, Phragmites australis Cav. and Panicum maximum Jacq. from Boskop in the North‐West Province and Oribi Gorge in KwaZulu‐Natal respectively. Populations of E. saccharina in different parts of Africa are known for their differences in larval feeding behaviours, host plant choice and natural enemies. It is important to understand the origin of the newly recovered population for prevention of incursion and efficient management in case it invades crops. Molecular analysis indicated that the populations recovered in these new locations and from the new host plants are part of the southern African population of E. saccharina. With change in climate, and disturbance in wetlands the insect is expected in the future to be more abundant and problematic in inland areas of southern Africa.     

Spatial dynamics of lepidopterous pests on Zea mays (L.) and Pennisetum purpureum (Moench) in the forest zone of Cameroon and their implications for sampling schemes

The most common lepidopterous borers attacking maize and/or the wild host Pennisetum purpureum in the forest zone of Cameroon are the noctuids Busseola fusca (Fuller), Sesamia calamistis (Hampson) and Poeonoma serrata (Hampson), the pyralids Eldana saccharina (Walker) and Mussidia nigrivenella (Ragonot), and Cryptophlebia leucotreta (Tortricidae). The within-plant distribution on maize and elephant grass was studied for the predominant species B. fusca , and on maize only for E. saccharina to determine the basic sampling unit. On both plant species, B. fusca showed a strong oviposition preference for young plant parts. By contrast, E. saccharina larvae and pupae on maize were only found on older plant parts indicating that it does not oviposit on young plants. No part of the plant strata appeared to be a stable sampling unit and it is recommended to carry out whole plant or whole tiller sampling for maize and grass, respectively. For the development of sampling plans, dispersion was described for all species using Taylor's power law and a non-linear model which gives the relationship between the proportion of infested plants [ P ( I )] and mean density ( m ). Busseola fusca egg batches as well as diapausing larvae and pupae on maize showed a random distribution whereas all the other cases were aggregated, with B. fusca egg batches on elephant grass exhibiting the lowest and M. nigrivenella on maize the highest aggregation. Optimal sample size/mean density curves were developed for groups of insects with low and high aggregation.     

FUNGAL ENDOPHYTES OF CYPERUS AND THEIR EFFECT ON AN INSECT HERBIVORE

Populations of the sedges Cyperus virens Michx. and C. pseudovegetus Steud. (Cyperaceae) in Louisiana often contain individuals infected by the systemic fungal endophyte Balansia cyperi Edg. (Clavicipitaceae, Ascomycetes). Related fungal endophytes infecting grasses are known to have detrimental effects on insect and mammalian herbivores consuming infected plants. In this study herbivory of infected and uninfected sedges was compared in two laboratory experiments. Newly hatched larvae of the fall armyworm (Spodoptera frugiperda [J. E. Smith], Noctuidae, Lepidoptera) were reared on leaves from either infected or uninfected plants of C. virens and C. pseudovegetus grown in the greenhouse. Survival, growth, and development of each insect were monitored. For both sedges larval survival and rate of weight gain were reduced, and length of the larval period was increased for larvae reared on leaves from infected plants compared to larvae reared on leaves from uninfected plants. The results of this study parallel results obtained from grasses, suggesting that the endophyte may defend its host against herbivory in natural populations.     

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.     

茶毛虫天敌的研究

本明确了茶毛虫天敌种类及其优势种：寄生性天敌中寄生卵的有赤眼蜂和茶毛虫黑卵蜂,其中茶毛虫绒茧蜂是优势种;寄生幼虫的有茶毛虫绒茧蜂、茶毛虫瘦姬蜂、小孢瘦姬蜂、日本黄茧蜂和寄蝇等,其中茶毛虫绒茧蜂是优势种;捕食性天敌有步行虫、蠼螋、蜘蛛和青蛙等,其中蜘蛛是优势类群,白斑猎蛛为优势种。研究了茶毛虫主要寄生性天敌的寄生率和寄生动态：茶毛虫黑卵蜂的寄生率为１５－２０％,越冬卵可高达４５％左右;茶毛虫绒茧蜂