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1.
Abstract:  Cat's claw creeper, Macfadyena unguis-cati , a major environmental weed in coastal and sub-coastal areas of Queensland and New South Wales, Australia is a target for classical biological control. Host specificity of Hypocosmia pyrochroma Jones (Lep., Pyralidae), as a potential biological control agent was evaluated on the basis of no-choice and choice larval feeding and survival, and adult oviposition preference tests, involving 38 plant species in 10 families. In no-choice tests, larval feeding and development occurred only on cat's claw creeper. In choice tests, oviposition and larval development was evident only on cat's claw creeper. The results support the host-specificity tests conducted in South Africa, and suggest that H. pyrochroma is a highly specific biological control agent that does not pose any risk to non-target plants tested in Australia. This agent has been approved for field release by relevant regulatory authorities in Australia.  相似文献   

2.
The Australian weevil Oxyops vitiosa was released in 1997 in Florida as a biological control agent of Melaleuca quinquenervia. The larvae of this agent are flush-feeders, found only on the growing tips of their host. Knowledge of this restriction to feeding on the growing tips and other nutritional requirements may assist in the establishment and dispersal of this species. Therefore, O. vitiosa survival was assessed when neonates were fed M. quinquenervia leaves from branches that had dormant buds or emerging bud leaves. Additionally, the influence of leaf quality from different sites and within sites was determined by the feeding of neonates emerging bud leaves collected at three sites and from three leaf qualities (poor, intermediate, and high). Within-site leaf qualities were described in the field by leaf color and in the laboratory by percentage dry mass and nitrogen. Larval survival was lowest when fed leaves from branches that had dormant buds. Associated with this low survival were high leaf toughness and percentage dry mass. When larvae were fed emerging bud leaves, most of the variation in larval survival and performance was attributed to differences in within-site plant quality. Generally, the highest-quality leaves had relatively low percentage dry mass and high percentage nitrogen. Larval survival generally decreased when fed the poor-quality leaves, and in one site, the intermediate-quality leaves. Larvae required less time to develop to adults when fed the high-quality leaves. Development time increased in females but not in males when the larvae were fed the poor-quality leaves. Adult biomass of both females and males generally increased when the larvae were fed the high-quality leaves from two of the three sites. The results indicate that the larvae of O. vitiosa are restricted to feeding on flush foliage with low toughness. Additionally, variations in foliar percentage dry mass and nitrogen influence larval survival and performance. This knowledge benefited the development of mass-production nursery sites and the selection of suitable release sites, which facilitated the establishment of this biological control agent.  相似文献   

3.
The main biological attributes of two Neotropical egg parasitoids, the arrhenotokous Trichogramma nerudai and the thelytokous Trichogramma sp., were assessed under controlled laboratory conditions. Developmental time from egg to adult, and parasitoid survival, fecundity and fertility were studied using life tables. Results showed that T. nerudai had a faster developmental time than Trichogramma sp. (13.014±0.4019 and 13.595±0.4931 days, respectively). Both species showed similar life table statistics, rm was 0.222 and 0.225 for T. nerudai and Trichogramma sp., respectively. Parasitoid survival averaged 95% for both species. The results obtained are discussed in the context of selecting one of these natural enemies as a potential biological control agent for the European pine shoot moth Rhyacionia buoliana (Lepidoptera: Tortricidae) in pine forests and the codling moth Cydia pomonella (Lepidoptera: Tortricidae) in apple orchards in Argentina.  相似文献   

4.
Abstract:  The life cycle of Tetrastichus turionum , a pupal endoparasitoid of the European pine shoot moth Rhyacionia buoliana , was studied in Spain in the field, prior to its use as a potential biological control agent of this pest in Chile. T. turionum showed two generations acting on the same host generation. Adults from the overwintering generation emerged and dispersed from mid- to late spring and gave rise to a fast developing, current year generation. Adults of this generation emerged and oviposited in early to mid-summer, producing progeny that overwintered as fourth instar larvae inside their host. Both generations appeared highly synchronized to the presence of pupae in the host population. The role of decreasing day length in the induction of diapause is also discussed. Laboratory bioassays showed that T. turionum did not oviposit on R. buoliana larvae already parasitized by Orgilus obscurator , a major larval parasitoid, already introduced in Chile. The results reinforce the suitability of T. turionum as a promising parasitoid that would complement O. obscurator in the biological control of European pine shoot moth.  相似文献   

5.
Abstract. 1. As a spring-feeding moth committed to immature foliage, the autumnal moth Epirrita autumnata (Lepidoptera, Geometridae) must have egg hatch synchronised with the bud-burst of its host plants. Due to large individual variation in the length of the pupal period, however, E. autumnata populations exhibit a prolonged period of flight and oviposition. Because the timing of oviposition in autumn is associated with the timing of egg hatch in the following spring, the time window for egg hatch expands and more potential hosts may become attainable. This suggestion was evaluated under field conditions by rearing E. autumnata eggs and larvae on four different hosts.
2. The performance of E. autumnata was measured by using estimates for fecundity (pupal mass) as well as survivorship of eggs and larvae. Based on the availability of foliage and phenological synchrony between larval and leaf development, early-laid eggs and the larvae originating from them were predicted to perform better on the hosts that have early-flushing leaves. On the late-flushing hosts, the larvae that hatched later were predicted to perform better than the larvae that hatched earlier. Half of the trials were exposed to predators and parasitoids, while the rest were conducted inside mesh-bags preventing larval dispersal and mortality due to natural enemies.
3. The results of the experiment did not support the simple predictions. In particular, host-plant quality and natural enemies appeared to operate discordantly between early- and late-laid eggs. Larvae from the late-laid eggs had rapid development during the larval stages and pupated at the same time and with the same pupal mass as the larvae hatched from the early-laid eggs.
4. The results indicate an occurrence of several, unknown selective forces in E. autumnata populations maintaining variation in the length of the pupal period, timing of oviposition, and timing of egg hatch.  相似文献   

6.
Abstract.  1. The aim of this 4-year observational study was to test for the presence of direct and delayed density-dependent larval melanism in the geometrid moth species Operophtera brumata (winter moth) in northern Norway.
2. Data from many populations with a wide range of population densities in time and space facilitated statistical analyses that could separate the effects of current and past density. The data also included different phases of the 10-year population cycle of this species so that eventual non-linear density effects due to population phase could be detected.
3. The results showed that the prevalence of melanism had a strong positive, linear relation to population density within years, whereas there was no evidence for a delayed effect from the year before or dependency on the phase of the population cycle.
4. In combination, these results limit the range of possible explanations of larval melanism in this outbreaking species. The possible reasons why winter moth larvae might benefit from crowding-induced melanism are discussed.  相似文献   

7.
Abstract:  We studied the mating selection in the cotton bollworm, Helicoverpa armigera (Hübner), in relation to body size and larval diet in the laboratory. When provided with an artificial diet at larval stage, weight, body and forewing length did not affect the probability of a male/female moth being selected for mating, but the abdominal width of selected female moths was significantly wider than that of non-selected female moths. 30 female moths were dissected and number of eggs was counted after mating, and there was a correlation between the abdominal width and egg number. There was also significant difference of weight loss between selected and non-selected male/female moths after the mating. The effect of operational sex ratio on mating latency and copulation duration were tested, and the result indicated that mating latency of male selection was significantly longer than that of female selection, but the difference of copulation duration was not significant. Cotton, corn and peanut plants were provided to larvae to test the effect of larval host plant experience on mate choice. When cotton- and peanut-fed moth severed as potential partners, both female and male of cotton-fed moths significantly preferred cotton- to peanut-fed moths for mating. The possible reasons for mate preference based on larval host plant experience may account for host plants attributes on sex pheromone variation and sexual maturity. These findings may impact Bacillus thuringiensis resistance management.  相似文献   

8.
The efficacy of lemon-scented tea tree oil (LSO), Leptospermum petersonii (FM. Bailey), was evaluated against the diamondback moth, Plutella xylostella (L.) under laboratory conditions. Feeding activity and development of larval stages were significantly reduced on broccoli leaves that had been dipped in LSO. Oviposition deterrence was also found when an adult stage was exposed to treated leaves. Fecundity dropped by >50% at concentrations >0.5%. The LC50 value for third instar larvae was estimated to be 2.93% 7 d after treatment. Experiments were also conducted under greenhouse conditions to assess the efficacy of LSO against the diamond-back moth. Our results suggest that LSO has modest potential for development as a botanical insecticide. The oil was also tested at concentrations from 0.5 to 6% for oviposition deterrence of an egg parasitoid of the diamondback moth, Trichogramma pretiosum (Riley). LSO deterred parasitization in choice tests but not in no-choice tests. LSO did not cause mortality of T. pretiosum during 24 h in a contact toxicity test. We conclude that LSO had no significant effects on the parasitoid, and therefore LSO is compatible with this biocontrol agent for integrated management of the diamondback moth.  相似文献   

9.
D. L. Isaacson 《BioControl》1973,18(3):291-303
The cinnabar moth,Tyria jacobaeae L. (Arctiidae), was introduced into Oregon in 1960 against the weed tansy ragwort,Senecio jacobaea L., and in 1970 an intensive study of a population of this biological control agent was initiated. Field sampling methods were devised, and laboratory investigations of feeding and larval development were conducted. Results of the study were analyzed and reported as partial life tables, where possible mortality factors were identified and quantified. The most important mortality factor in both 1970 and 1971 was starvation after defoliation of host plants. Other factors identified included pupal death, emergence failure, egg predation, and larval ingestion of eggs.  相似文献   

10.
Cactoblastis cactorum Berg (Lepidoptera: Pyralidae), the cactus moth, is a well-known biological control agent of prickly pear cactus (Cactaceae: Opuntia Miller). The arrival of the moth in Florida and its subsequent spread through the southeastern United States poses a threat to opuntioid diversity in North America. Of particular concern are the ecological and economic impacts the moth could have in the southwestern United States and Mexico, where both native and cultivated Opuntia species are important resources. It is unknown which species would best support larval development if the moth were to spread further westward in North America. This study aimed to determine if ovipositing females demonstrate preferences for any of 14 common opuntioids native to or naturalized in Mexico and the southwestern United States; which of these opuntioids best support larval development; and if oviposition preference correlates with larval performance, as predicted by simple adaptive models. Results from a field experiment showed that female moths preferred O. engelmannii Salm-Dyck ex Engelmann variety linguiformis (Griffiths) Parfitt and Pinkava and O. engelmannii variety engelmannii for oviposition. A generalized linear model showed number of cladodes and degree of spininess to be significant predictors of oviposition activity. Results from a no-choice larval survival experiment showed Consolea rubescens (Salm-Dyck ex de Candolle.) Lemaire and O. streptacantha Lemaire to be the best hosts. Epidermal toughness was a significant predictor of most larval fitness parameters. In general, oviposition preference was not correlated with larval performance. A lack of co-evolutionary history between C. cactorum and North American opuntioid species may help explain this disconnect.  相似文献   

11.
Codling moth, Cydia pomonella Linnaeus (Lepidoptera: Tortricidae), is a serious pest of apples worldwide. This study aimed to evaluate the mortality rate of codling moth eggs, larvae and pupae in the field in commercial and neglected apple and walnut orchards over two years, and to investigate the biodiversity and intensity of parasitoids associated with codling moth in the orchards. Five patches of wax paper containing 1-day-old codling moth eggs were placed in a neglected orchard in order to evaluate parasitism rates. Corrugated cardboard bands were placed around the trunk of 15 trees during late spring and the beginning of summer through to fruiting season to capture and measure parasitism of codling moth larvae. 5285 larvae in total were collected during this study. Mortality rate (egg?+?larvae?+?pupae) varied between the commercial and neglected orchards, reaching a maximum of (42.89% and 66.67%) in neglected apple orchards and (61.03% and 74.76%) in the neglected walnut orchard in 2003 and 2004, respectively. Trichogramma cacoeciae (Hymenoptera: Tichogrammatidae) was the only egg parasitoid recorded. Eight hymenopteran larval and pupal parasitoids belonging to several subfamilies were recorded: Cheloninae, Agathidinae, Cremastinae, Haltichellinae, Chalcidinae, Anomalinae, and Pteromalinae and one dipteran belonging to Tachininae. In conclusion, mortality factors, mainly by parasitoids, are contributing to a general reduction in codling moth larvae populations particularly in neglected orchards. The hymenopteran Ascogaster quadridentata and the dipteran Neoplectops pomonellae can contribute to biological control programmes against codling moth in the coastal region and other regions.  相似文献   

12.
Abstract:  The two-spotted stink bug, Perillus bioculatus (F) (Hem., Pentatomidae) is considered an important predator of Colorado potato beetle egg masses and small larvae. The susceptibility of P. bioculatus second instar nymphs to six isolates of Beauveria bassiana (Balsamo) Vuillemin, which are highly pathogenic to Colorado potato beetle, was tested in the laboratory. Five isolates were highly pathogenic and caused more than 77% mortality after 8 days at a concentration of 106 conidia/ml. However, isolate IPP46 showed low pathogenicity and caused only 11% mortality of nymphs. The pathogenicity of isolates was independent of their host, source or country of origin. Isolate IPP46 was tested at six different concentrations. A linear relationship between the concentration of B. bassiana and the mortality of nymphs was observed. The 50% lethal concentration (LC50) value was 3.4 × 107 conidia/ml. The LT50 decreased with increase of conidia concentration used. The present results suggest that isolate IPP46 has good potential as a biological control agent within an integrated pest management programme.  相似文献   

13.
The life cycle and host range of Charidotis pygmaea Klug were investigated to assess its suitability for release as a biological control agent for Lantana camara L. and L. montevidensis (Sprengel) Briquet. Adults fed and deposited eggs on the underside of leaves of both species. They generally laid fewer eggs in the dry winter months when lantana yellows or drops its leaves. Larvae fed on the upper leaf surface and pupation occurred on the leaves or stems. Development from egg to adult took approximately 50 days. Survival to the adult stage was greater, and the development time was shorter on L. montevidensis than on all varieties of L. camara tested, suggesting that the agent would be ineffective against L. camara. Forty-two plant species were tested to determine host specificity in choice oviposition and larval feeding trials. These demonstrated that C. pygmaea did not pose a threat to non-target species. Consequently, C. pygmaea was approved for release in Australia and through its ability to survive the dry season, should assist in the control of L. montevidensis.  相似文献   

14.
《Biological Control》2005,32(1):121-129
Parasitism can limit the effectiveness of weed biological control agents. In this study, we surveyed larval and pupal parasitoids of the leaf-tying moth, Evippe sp. #1 (Gelechiidae), a biological control agent released widely in rangeland Australia against mesquite (Mimosaceae: Prosopis spp.). This moth was expected to be vulnerable to parasitism, as it has a semi-concealed feeding habit, is a member of a well-represented family, and is a herbivore on a well-represented family of trees and shrubs. We conducted surveys in four regions across Australia to determine whether parasitoids were responsible for differential performance of the moth in rangeland Australia, and what the consequences might be for the release of further semi-concealed Lepidoptera. The parasitoid fauna was found to be diverse, but the composition was similar across the four regions surveyed. It included primary and hyperparasitoids of both larvae and pupae. Parasitism rates were generally low, rarely above a few percentage points in any one survey, and therefore, unlikely to threaten moth populations. There was also no relationship between parasitism rates and leaf-tie abundance. These results suggest that any new semi-concealed lepidopteran biological control agents in rangeland Australia might also be parasitised by a diverse fauna. However, a better understanding of what determines parasitism rates is required to predict whether it would be sufficient to threaten biological control.  相似文献   

15.
Summary The interactions between cinnabar moth, Tyria jacobaeae L. and its food plant, tansy ragwort, Senecio jacobaea L. were studied for 4 to 6 years at 9 sites in North America to assess if the herbivore drove the dynamics of the plants or if the plants determined the dynamics of the insects. Cinnabar moth larval density is not closely related to changes in the size and spacing of tansy ragwort plants although high densities of larvae were associated with a high proportion of rosettes the next year. Fluctuating moth populations live in areas where rosettes are small, closely spaced and numerous compared to flowering stem plants. This situation is also associated with greater larval dispersal which may lead to over exploitation of the food supply. The coefficient of variation of both the size of rosettes and the distance between clumps of plants is associated with the coefficient of variation in moth density. This suggests that the plants may be driving the dynamics of the insect populations. The size of the moth egg batches is correlated to the size of the flowering stem plants in the previous year, indicating an adjustment between moth fecundity and food plant size. The conclusion is that environmental factors such as weather and soil type determine to a large degree the characteristics and variation in the plant populations and this in turn controls the dynamics of the insects. The relation of this situation to the biological control of weeds is discussed.  相似文献   

16.
1 The tri‐voltine moth Prays oleae Bern. spends its larval stages on the native olive tree (Olea europaea L. var. sylvestris Brot. and five cultivars, Oleaceae) mining the leaves, the flowers and the fruits in each generation; it seldom switches to other native or introduced confamilial plant species. 2 In this study the pattern of oviposition of the olive moth was examined in olive fields and natural vegetation, in relation to in situ recruitment as an outcome of processes such as density dependence or risk spreading. 3 Larval body size (width of epicranial sclerites) was also examined and compared between host substrates, years and morphological, physiological, ecological and nutritional attributes of the host. 4 The factors influencing the oviposition pattern of the olive moth such as the carbon/nitrogen ratio, number of flowers, branch length and previous leaf damage were ranked differently in different cultivars. 5 ‘Hot spots’, i.e. olive trees or parts of trees receiving a high egg load, were found to be the result of in situ recruitment. 6 Physiological mortality among first instar larvae was significantly negatively correlated with the number of oviposited upon leaves; suggesting that the adult selects for oviposition the best available substrate. 7 As adult moths selected leaves with minimal probability of abscission for oviposition, leaf abscission was not a major mortality factor, although first instar larvae reduced leaf longevity. 8 Host quality did not affect all larval stages in the same way. 9 The more nutritionally poor the substrate, the longer the duration of the larval stage feeding on it. The phenological timing of the insect life stages very closely tracks the phenological phases of its host plant, primarily focusing on the most nutritious host stage in terms of larval performance.  相似文献   

17.
This study investigated the effect of temperature on the development and overwintering potential of the predatory thrips Franklinothrips vespiformis (Crawford) (Thysanoptera: Aeolothripidae), a biological control agent used against glasshouse pests in continental Europe and Israel. Developmental rates increased linearly with rearing temperatures. It was estimated that 304.9 degree days, above a lower threshold temperature of 11.9 °C, were required for F. vespiformis to complete development from egg to adult eclosion. The effect of low temperatures (–5, 0, and 5 °C) was examined on adult female and larval survival. Subsequent reproductive and developmental attributes of survivors were also investigated. Lethal time experiments indicated that larval stages are more cold tolerant than adult F. vespiformis females. Surviving larvae increased their developmental times to adults with decreasing temperature and increasing exposure periods and second instars were significantly more successful than first instars in reaching adulthood. Surviving adult females decreased their oviposition rate with decreasing temperature and increasing exposure periods, and exposures to low temperatures affected the number of viable eggs produced. The results are discussed in the context of overwintering and establishment potential of F. vespiformis in the UK in the event of introducing the predatory thrips as a biological control agent against glasshouse pests.  相似文献   

18.
The objective of this work was to study the effect of plant canopy height on the resistance of the tomato species Lycopersicon hirsutum to the tomato leafminer Tuta absoluta . Determination of the levels of tridecan-2-one (2-TD) and undecan-2-one (2-UD) in L. hirsutum , as well as the leaf area, density and types of trichomes present in L. hirsutum and L. esculentum were made on apical, medium and basal parts of plant canopy. Correlation of these data were made with the following biological characteristics of T. absoluta : rates of oviposition and egg hatching; length of egg, larval and pupal stages; mortality of the larval and pupal stages; pupal weight; and sex ratio. Levels of 2-TD on leaves of L. hirsutum increased from bottom to top of canopy. Tuta absoluta had higher oviposition and egg hatching, as well as lower mortalities and smaller larval and pupal periods in L. esculentum than in L. hirsutum . Longer pupal period and greater number of small and large mines of T. absoluta were verified in the apical and medium parts of L. hirsutum plants. On the other hand, higher pupal mortality and longer larval periods were obtained in the apical and basal parts of the L. hirsutum plants. Larval mortality was higher in the basal part of those plants. In L. esculentum , leaves from the apical part of the plant promoted lower mortality, longer larval period and greater number of large mines of T. absoluta . However, a shorter pupal period was verified on leaves of the basal part. It appears that an increase in glandular trichome density in L. hirsutum leads to an increase in the levels of 2-TD, which, in turn slows down larval development.  相似文献   

19.
Maternally inherited endosymbiotic bacteria of the genus Wolbachia induce various kinds of reproductive alterations in their arthropod hosts. In a Wolbachia-infected strain of the adzuki bean borer moth, Ostrinia scapulalis (Lepidoptera: Crambidae), males selectively die during larval development, while females selectively die when Wolbachia are eliminated by antibiotic treatment. We found that naturally occurring Wolbachia in the congener O. furnacalis caused sex-specific lethality similar to that in O. scapulalis. Cytogenetic analyses throughout the entire larval development clarified that the death of males (when infected) and females (when cured) took place mainly during early larval stages. However, some individuals also died after complete formation of larval bodies but before egg hatching, or at late larval stages, even in the penultimate instar. Although the specific timing was highly variable, death of males and females occurred before pupation without exception. The potential association of sex-specific lethality with the sex determination mechanism was also examined and is discussed.  相似文献   

20.
The insect growth regulators (IGRs) tebufenozide and methoxyfenozide and the broad-spectrum insecticides azinphosmethyl, carbaryl, and fenpropathrin were compared for their activity against adult, egg, and larval stages of the grape berry moth, Endopiza viteana (Clemens) (Lepidoptera: Tortricidae), under laboratory and vineyard conditions. Adult mortality was not affected by exposure to field-equivalent rates of tebufenozide or methoxyfenozide on grape clusters, whereas all the broad-spectrum compounds significantly reduced adult survival, compared with the untreated controls. Surviving adult moths laid significantly more eggs on berries treated with the IGRs than on berries treated with any of the broad-spectrum insecticides. Survival of these eggs through to late larval and pupal stages was significantly lower on methoxyfenozide-treated grapes than on untreated grapes, and no pupae were found when grapes were treated with azinphosmethyl or fenpropathrin. Neither of the growth regulator insecticides limited egg eclosion or larval development by E. viteana when insecticides were applied before egg laying, whereas broad-spectrum insecticides were effective against both eggs and neonates at this timing. When applied after egg eclosion, all insecticide treatments significantly reduced survival of grape berry moth larvae. Under vineyard conditions, berries with 1-d-old residues of tebufenozide or methoxyfenozide received more E. viteana eggs than berries treated with broad-spectrum compounds. After aging for 7 or 14 d, no significant effects on E. viteana survival were detected among treatments. Whereas broad-spectrum insecticides provide control of multiple life stages of E. viteana, integration of tebufenozide or methoxyfenozide into vineyard management programs for control of this pest will be most successful if applications are timed for egg hatch.  相似文献   

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