筛豆龟蝽卵寄生蜂田间发生调查初报

调查表明 ,筛豆龟蝽卵雌虫从 5月初开始产卵 ,5月中旬到 6月底为产卵高峰期 ,接着进入产卵衰退期 ,高峰期产卵量占 80 4%。通过有机毛豆田间标记筛豆龟蝽卵块 ,共发现 2种卵寄生蜂 :卵跳小蜂Ooencyrtussp .和沟黑卵蜂Trissolcussp .。结果发现 :卵跳小蜂是优势种 ,在自然控制因素中起主要的作用。寄生蜂和筛豆龟蝽卵发生动态基本一致 ,寄生蜂数量与寄主卵数量正相关。自然状态下 ,寄生蜂对筛豆龟蝽第 1代卵平均寄生率为 61 3 6%。寄生蜂的羽化集中于毛豆灌浆初期 ,高峰期内 1周羽化量占 81 3 3 %。     

A comparison of the host preference of monarch butterflies (Danaus plexippus) for milkweed (Asclepias syriaca) over dog-strangler vine (Vincetoxicum rossicum)

Observations in the field indicate that monarch butterflies will oviposit on dog‐strangler vine, an invasive introduced species in the same family as milkweed (Asclepias spp.), the principal larval host of monarchs. The potential impact of this behaviour depends on the strength of the preference of monarch adults to oviposit on these two hosts and the relative ability of larvae to survive on each. We determined the preference for milkweed vs. dog‐strangler vine of ovipositing adults and first instar larvae in choice and no‐choice tests. We also compared the ability of larvae to consume, develop, and survive on either host. In the presence of both hosts, adults exhibited a strong preference to oviposit on milkweed over dog‐strangler vine (mean 80.7 eggs compared to 0.4 eggs over 48 h, respectively). In the absence of milkweed, adults ceased oviposition (mean 0.9 eggs in 48 h), but resumed oviposition when the dog‐strangler vine was replaced with milkweed (mean 99.1 eggs in 48 h). Given a choice between hosts over 24 h, 92% of larvae moved to milkweed leaves and consumed 3.94 cm² of milkweed leaves compared to 2% of larvae that moved to dog‐strangler vine and consumed negligible amounts of leaf material (0.01 cm²). Without a choice, larvae on dog‐strangler vine never consumed more than mean 0.02 cm² larva^?1 in a 24‐h period, did not develop beyond the first instar, and died within 96 h. We obtained no data in support of an effect of the presence of dog‐strangler vine on monarch butterfly populations.     

Some host-plant factors affecting oviposition by aphidophagous Syrphidae (Diptera)

Although most aphidophagous syrphid species lay their eggs close to aphids, Platycheirus peltatus (Meig.), Melanostoma scalare (F.) and M. mellinum (L.) laid freely on uninfested brussels sprout plants. The existence of species that will lay in the absence of aphids may be valuable in biological control and also provides a useful tool for the investigation of non-aphid oviposition stimuli. Plant species and plant appearance were both important factors in P. peltatus oviposition. Particular sites on the plant were chosen for oviposition by Syrphus balteatus (Deg.). The nature of the substrate at the oviposition site affected the size of the egg batches laid there by M. scalare, M. mellinum, P. peltatus and P. clypeatus (Meig.). The possibility is discussed that plant-location is the older-established system of host-finding and that an aphid-location system has gradually superseded it during the evolution of the obligatorily aphidophagous Syrphinae.     

Influence of preceding crop on wireworm (Coleoptera: Elateridae) abundance in the coastal plain of North Carolina

Three studies were conducted to determine the effect of preceding crop on wireworm (Coleoptera: Elateridae) abundance in the coastal plain of North Carolina. In all three studies, samples of wireworm populations were taken from the soil by using oat, Avena sativa L., baits. Treatments were defined by the previous year's crop and were chosen to reflect common crop rotations in the region. Across all three studies, eight wireworm species were recovered from the baits: Conoderus amplicollis (Gyllenhal), Conoderus bellus (Say), Conoderus falli (Lane), Conoderus lividus (Degeer), Conoderus scissus (Schaeffer), Conoderus vespertinus (F.), Glyphonyx bimarginatus (Schaeffer), and Melanotus communis (Gyllenhal). The effect of corn, Zea mays L.; cotton, Gossypium hirsutum L.; fallow; soybean, Clycine max (L.) Merr.; sweet potato, Ipomoea batatas (L.) Lam.; and tobacco (Nicotiana spp.) was evaluated in a small-plot replicated study. M. communis was the most frequently collected species in the small-plot study and was found in significantly higher numbers following soybean and corn. The mean total number of wireworms per bait (all species) was highest following soybean. A second study conducted in late fall and early spring assessed the abundance of overwintering wireworm populations in commercial fields planted to corn, cotton, peanut (Arachis hypogaea L.), soybean, sweet potato, and tobacco in the most recent previous growing season. C. lividus was the most abundant species, and the mean total number of wireworms was highest following corn and soybean. A survey was conducted in commercial sweet potato in late spring and early summer in fields that had been planted to corn, cotton, cucurbit (Cucurbita pepo L.), peanut, soybean, sweet potato, or tobacco in the most recent previous growing season. C. vespertinus was the most abundant species, and the mean total number of wireworms per bait was highest following corn.     

Seasonal abundance and reproductive season of <Emphasis Type="Italic">Chauliops fallax</Emphasis> (Heteroptera: Malcidae) on kudzu <Emphasis Type="Italic">Pueraria lobata</Emphasis>

We investigated the seasonal abundance and seasonal dynamics of reproduction in the stalk-eyed bug Chauliops fallax Scott, which is described as a minor pest of bean plants such as soybean and a minor cause of pecky rice. We counted the number of adult males and females, mating pairs, and nymphs of C. fallax on kudzu plants, Pueraria lobata (Willd.), in the southern part of Okayama City, Japan, from 2005 to 2007 and in 2009. Two peaks in abundance for mating pairs were found in late May and August. Both male and female solitary adults appeared from late April, and two peaks of solitary adults were found in May and September. Two clearly separate peaks of nymphs were found in late June and late August. Therefore, it seems that C. fallax produces two generations a year in the southern Okayama area. These data may provide essential information for pest control, and therefore, we discuss them from an applied entomological standpoint to predict invasions by C. fallax into agriculture fields from weeds that grow around and/or in fields.     

Biology and preliminary host range assessment of two potential kudzu biological control agents

Two insect species from China, Gonioctena tredecimmaculata (Jacoby) (Coleoptera: Chrysomelidae) and Ornatalcides (Mesalcidodes) trifidus (Pascoe) (Coleoptera: Curculionidae), were studied in quarantine in the United States as potential biological control agents for kudzu, Pueraria montana variety lobata (Willd.) Maesen and S. Almeida. Adults of G. tredecimmaculata were ovoviviparous and reproduced throughout the summer, producing offspring that had an obligate adult diapause. In no-choice tests, adult and larval G. tredecimmaculata rejected most of the plant species tested, but consumed foliage and completed their life cycle on soybean (Glycine max L. Merr.) and on a native woodland plant, hog-peanut (Amphicarpaea bracteata L. Fernald), which are in the same subtribe as kudzu (Glycininae). Insects showed similar responses to field- and greenhouse-grown soybean and kudzu foliage, despite measurable differences in leaf traits: field-grown foliage of both plants had greater leaf toughness, higher total carbon content, higher trichome density, and lower water content than greenhouse foliage. O. trifidus adults also rejected most of the plants tested but fed on and severely damaged potted soybean and hog-peanut plants in addition to kudzu. Further tests in China are needed to determine whether these species will accept nontarget host plants under open-field conditions.     

Evaluating legume species as alternative trap crops to chickpea for management of Helicoverpa spp. (Lepidoptera: Noctuidae) in central Queensland cotton cropping systems

Mounting levels of insecticide resistance within Australian Helicoverpa spp. populations have resulted in the adoption of non-chemical IPM control practices such as trap cropping with chickpea, Cicer arietinum (L.). However, a new leaf blight disease affecting chickpea in Australia has the potential to limit its use as a trap crop. Therefore this paper evaluates the potential of a variety of winter-active legume crops for use as an alternative spring trap crop to chickpea as part of an effort to improve the area-wide management strategy for Helicoverpa spp. in central Queensland's cotton production region. The densities of Helicoverpa eggs and larvae were compared over three seasons on replicated plantings of chickpea, Cicer arietinum (L.), field pea Pisum sativum (L), vetch, Vicia sativa (L.) and faba bean, Vicia faba (L.). Of these treatments, field pea was found to harbour the highest densities of eggs. A partial life table study of the fate of eggs oviposited on field pea and chickpea suggested that large proportions of the eggs laid on field pea suffered mortality due to dislodgment from the plants after oviposition. Plantings of field pea as a replacement trap crop for chickpea under commercial conditions confirmed the high level of attractiveness of this crop to ovipositing moths. The use of field pea as a trap crop as part of an area-wide management programme for Helicoverpa spp. is discussed.     

Factors influencing adult female oviposition in the citrus leafminer Phyllocnistis citrella

1 The citrus leafminer (CLM) Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) is a serious pest in most citrus‐growing regions of the world. The influence of leaf length, citrus species or variety, leaf colour tone and temperature on CLM oviposition was studied from field observations and laboratory experiments. The spatial distribution of eggs on leaves was also examined. Field data were obtained from 1100 samples collected in eastern Spain for 7 years. 2 Significant differences in oviposition rate were found among citrus species in ‘no choice’ laboratory experiments. This tendency was not apparent in the field due to the confounding effect of such factors as the intensity of new flushes and adult CLM abundance. Leaf colour tone and air temperature in the range studied (18–27°C) had no effect on CLM egg‐laying. 3 The distribution of eggs among leaves was random for population densities lower than four eggs per leaf, but became strongly aggregated above this, when not all eggs could survive and complete development. 4 The CLM developmental stage found on leaves depended on the leaf length, and most of the egg‐laying occurred only on leaves that were 10–25 mm long. These leaves had the highest CLM stages in the field and thus give the best estimate of CLM oviposition.     

The pollen beetle, Meligethes aeneus, changes egg production rate to match host quality

Motivation-based models dominate current theory concerning host plant selection for oviposition by herbivorous insects. A female searching for a host plant will be more likely to accept a host which is of inferior quality for her offspring if motivation is high, e.g. a large eggload or long time since last oviposition. This implies that insects will accumulate eggs if exposed to hosts of low acceptability and after a time lay eggs on such hosts. An alternative strategy for insects when exposed to less acceptable hosts is to stop producing, instead of accumulating, eggs. Thus, resources would be saved until a more acceptable host is found. If this hypothesis is true, a herbivorous insect would cease egg production when exposed to hosts of low acceptability and resume egg production when exposed to hosts of high acceptability. Previous exposure should not affect oviposition rate when an insect encounters a new host of a different quality. In an earlier study pollen beetles, Meligethes aeneus (F.) (Coleoptera: Nitidulidae), did not accumulate eggs in the absence of high quality hosts. In this study we monitored the daily oviposition rate of female pollen beetles on hosts plants of low (Sinapis alba L.), intermediate (Brassica nigra Koch) or high (B. napus L.) acceptability over a 5-day period. Individuals were then switched to an oviposition resource of a different acceptability. Beetles moved from high- to low-acceptability plants reduced their oviposition rate considerably. In the opposite case, low to high acceptability, the rate of oviposition increased markedly after the switch. When M. aeneus were moved from the high-acceptability host to that of intermediate acceptability oviposition rate was modified accordingly. However, when moved to the intermediate host from a host of low acceptability oviposition on B. nigra was much less than would normally be expected. A possible mechanism for this finding is discussed. M. aeneus, by adjusting oviposition rate to host acceptability, maximizes the average host quality for offspring, even at the cost of a lower egg-laying rate. Received: 5 October 1998 / Accepted: 20 April 1999     

Soybean looper (Lepidoptera: Noctuidae) oviposition on cotton and soybean of different growth stages: influence of olfactory stimuli

Soybean looper, Pseudoplusia includens (Walker), oviposition in cotton, Gossypium hirsutum L., and soybean, Glycine max (L.) Merr., of various stages of plant phenological development was evaluated in field cages in 1994, 1995, and 1996. Overall, females preferred to oviposit on soybean over cotton when both crops were compared in vegetative or prebloom stages, when both crops were blooming, and when soybean was blooming or in early pod stage compared with prebloom cotton. Females preferred to deposit eggs on the lower leaf surface in the upper two-thirds of the plant canopy in cotton and soybean. Oviposition in upper and middle canopy levels varied with plant growth stage. Females tended to lay more eggs in the upper canopy compared with the middle canopy in prebloom cotton and vegetative soybean; more eggs were laid in the middle canopy of blooming cotton and reproductive stages of soybean. Females responded to both cotton and soybean volatiles in an olfactometer. There was no significant difference in response to the two sources of volatiles.     

草地螟对寄主植物的选择性及其化学生态机制

田间自然条件下,草地螟成虫产卵对不同植物具有明显的选择性,其中灰菜上落卵量最多,占调查总卵量的50%以上;甜菜、大豆上次之,玉米和马铃薯上最少。在室内条件下,草地螟成虫产卵对灰菜、大豆、玉米和马铃薯的选择性与田间调查结果完全吻合。而且,草地螟幼虫的嗜食性与成虫产卵对寄主的选择性是一致的。吸附、收集上述植物的挥发物后进行GC-MS测定,并利用风洞进行了生测。其中灰菜和大豆的主要挥发物成分为反-2-己烯醛、青叶醇、青叶酯、1-十八烯等;玉米和马铃薯的挥发物性成分包括青叶酯、芳樟醇、香叶醇、紫罗酮、1-十八烯。生测结果表明,灰菜的挥发物对草地螟雌蛾引诱力最大,选择系数为78%;大豆苗挥发物对其也有较高的诱虫活性;但玉米和马铃薯几乎无引诱作用。自然生长的4种植物的诱虫结果与其挥发物的诱虫结果相似。这些生测结果与成虫和幼虫选择寄主的一致性反映了草地螟选择寄主行为的化学机制。     

Natural and human dimensions of a quasi-wild species: the case of kudzu

The human dimensions of biotic invasion are generally poorly understood, even among the most familiar invasive species. Kudzu (Pueraria montana (Lour.) Merr.) is a prominent invasive plant and an example of quasi-wild species, which has experienced repeated introduction, cultivation, and escape back to the wild. Here, we review a large body of primary scientific and historic records spanning thousands of years to characterize the complex relationships among kudzu, its natural enemies, and humans, and provide a synthesis and conceptual model relevant to the ecology and management of quasi-wild invasive species. We documented over 350, mostly insect, natural enemy species and their impacts on kudzu in its native East Asian range. These natural enemies play a minor role in limiting kudzu in its native range, rarely generating severe impacts on populations of wild kudzu. We identified a number of significant influences of humans including dispersal, diverse cultural selection, and facilitation through disturbances, which catalyzed the expansion and exuberance of kudzu. On the other hand, harvest by humans appears to be the major control mechanism in its native areas. Humans thus have a complex relationship with kudzu. They have acted as both friend and foe, affecting the distribution and abundance of kudzu in ways that vary across its range and over time. Our conceptual model of kudzu emphasizes the importance of multiple human dimensions in shaping the biogeography of a species and illustrates how kudzu and other quasi-wild species are more likely to be successful invaders.     

Oviposition on host plants by a tropical forest grasshopper (Microtylopteryx hebardi: Acrididae)

Abstract. 1. The tropical forest grasshopper Microtylopteryx hebardi Rehn (Orthoptera, Acrididae, Ommatolampinae) oviposits inside leaves or stems of its host plants. This is the first known instance of oviposition inside living plant tissue (rather than in the ground, on top of leaves, or in detritus) for a tropical forest acridid.
2. In understorey secondary forest at La Selva, Costa Rica, M.hebardi females fed on fifteen species of host plants, but oviposited in only four of these.
3. In laboratory choice tests, females showed selectivity for oviposition host plants similar to that inferred from field observations.
4. Plant volume was a better predictor of the number of eggs laid per stem than variables that indicated leaf or stem characteristics of individual plants.
5. Unlike the ovipositor of acridids laying eggs in the ground, that of M.hebardi is equipped with toothed, sclerotized edges, probably used to bore into plant tissue.
6. Endophytic oviposition in M.hebardi may be related to finding host plants in a habitat that is complex, heterogeneous, and rich in plant species.     

Age structure and abundance in populations of muscoid flies from a poultry facility in Southeast Brazil

Muscina stabulans, M. domestica, Chrysomya putoria, C. megacephala and Stomoxys calcitrans were the most abundant muscoid flies captured in a poultry facility in southeastern Brazil. We examined the gonadotrophic profiles of the females caught at different sites and different times and found that Mu. stabulans and M. domestica, the predominant species, presented similar gonadotrophic profiles only when captured on the manure under the cages, but very different and sometimes opposite gonadotrophic profiles when sampled from wooden posts, vegetation or electric cords. We also determined sex ratios and relative abundance for these two species and found significant differences between them. More than 50% of the females of both species of Chrysomya captured on manure carried eggs or exhibited signs of recent oviposition. The vast majority of S. calcitrans presented ovaries with eggs or signs of recent oviposition. A small proportion of them had ovaries in the recent emerged condition. Our data on ovarian stages, sex ratio and relative abundance allowed us to associate different gonadotrophic profiles with each site and characterize each site as a resting, ovipositing or mating site.     

Ecological correlates and heritability of reproductive variation in two co-occurring grasshopper species

ABSTRACT. 1. Relationships are examined between mean egg size and possible selection pressures acting on two grasshopper species, Chorthippus brunneus (Thunb.) and Myrmeleotettix maculatus (Thunb.), co-occurring at three sites in a sand dunes area.
2. Heavy eggs were laid where the mean crowding of hatchlings was high in relation to the amount of grasses with thin-edged leaves. To a lesser extent, large eggs were also found in more desiccating conditions. Mean egg dry weights did not correlate with measures of crowding or measures of crowding in relation to total grass abundance.
3. Significant differences in egg size and clutch sizes were observed between the stocks of second generation, laboratory-reared M.maculatus from three study sites. The significant difference in egg size (site 2 stock > site 1 stock) ran counter to the difference observed in the field but the difference in clutch size (site 3< site 2) was consistent with that observed between field populations.
4. We argue that egg size is primarily determined by selection pressures on the size of hatchlings but that predictably poor feeding conditions for juveniles and adults at site 2 results in the production of smaller adults which, in M.maculatus , then lay smaller eggs. We further argue that M. maculatus from site 2 have been selected to lay larger eggs for their body size and body condition in order to compensate partially for this environmental constraint.     

Pollen beetle (Meligethes aeneus) oviposition and feeding preference on different host plant species

The oviposition and feeding preferences of the pollen beetle, Meligethes aeneus, were determined in choice and no-choice tests in field, semi-field and greenhouse trials. Plant species used were Brassica napus, B. campestris, B. juncea, B. nigra, B. carinata, Sinapis alba and Crambe abyssinica. With respect to number of eggs laid, S. alba and C. abyssinica were inferior to the other species. Pollen beetles laid fewer eggs on B. nigra than on the other Brassica spp. in no-choice tests, however this difference was partly due to fewer eggs laid per bud rather than fewer buds used for oviposition. Most eggs, for all plant species, were deposited in buds sized 2–3 mm. Feeding damage on all plant species was relatively similar. Pollen beetles seem to have a wider host range for feeding than for oviposition. There was good agreement in plant species ranking as oviposition hosts between the field, semi-field and greenhouse trials.     

Performance and host preference of Ascia monuste (Lepidoptera,Pieridae)

Experiments were conducted to determine the performance and host preference of Ascia monuste using kale (Brassica oleraceae, var. Acephala) and mustard (B. juncea). These plants differ significantly in water and nitrogen content, with mustard having larger amounts of water and kale larger amounts of nitrogen. The performance results confirmed that kale is a better food source than mustard for the species, even when eggs were collected on mustard leaves in the field. However, when eggs were collected on mustard, the kale nutritive value was lower than the nutritive value obtained when eggs were collected on kale leaves. Furthermore, the results of oviposition preference obtained in the field and in the laboratory have shown a preference for kale, indicating the presence of a positive correlation with performance. In contrast to the data about oviposition preference, there was no immature feeding preference. These results indicate that host selection occurs during the oviposition process. Furthermore, it is possible that the high abundance of kale cultivated in the region studied and the nutritional quality of this plant are two factors that influence the positive relationship between oviposition preference and performance for A. monuste.     

Seasonal change in the spatial utilization of host mussels in relation to ovipositor length by female rosy bitterling Rhodeus ocellatus kurumeus

The seasonal changes in ovipositor length and utilization patterns of mussels for oviposition in the rosy bitterling Rhodeus ocellatus kurumeus (Cyprinidae) were investigated in a field experiment and field surveys during the breeding period (April to August). The mean length of ovipositors at oviposition was short at the start (early April) and end (July) of the breeding period. Females with long ovipositor at oviposition were collected between mid‐April and June. Mark‐and‐recapture data showed that ovipositor length at oviposition changed rhythmically throughout the breeding period, shortening and lengthening as the female entered the spawning and resting phase. The density of rosy bitterling embryos in mussels increased between April and June, peaking in May, but decreasing in July. The position of eggs on mussel gills varied from close to the exhalant siphon to deeper inside the gill during April, and periodically thereafter. There was a positive correlation between ovipositor length at oviposition and the distance from exhalant siphon of mussels to eggs deposited by females, suggesting that ovipositor length at oviposition determined the position of eggs deposited on a mussel gill. Because dissolved oxygen in mussel gills decreased with the density of bitterling embryos, suitable positions for embryo survival in gills changed with embryo density. By changing ovipositor length at oviposition, females might be able to spawn their eggs in a position that maximizes embryo survival. Thus, plasticity in ovipositor length at oviposition may play an important role as an adaptation of rosy bitterling in utilizing mussels when their quality as a spawning substratum fluctuates seasonally.     

Body size and resource partitioning in ladybirds

Aphidophagous insects all exploit aphids as food, but there appears to be no association between the size of the aphidophagous predator and that of the species or the age structure of the aphid colonies they exploit. Aphid colonies generally increase, peak and decline in abundance, and are exploited by a sequence of predators, which is consistent from year to year. The objective of this study was to determine the rules underlying this temporal pattern. For example, in the field, aphid colonies are often first attacked by a small and then a larger species of ladybird. Theory based on the geometry and physiology of ladybirds predicts that the quantity of food required for oviposition and the area searched per unit time should scale with body weight, with exponents of 1 and 0.66, respectively. An analysis of empirical data supports these predictions. Thus, in relative terms a 35 mg ladybird requires 1.5 times more aphids per unit area for oviposition than a 10 mg ladybird. That is, the temporal pattern in oviposition is possibly mainly determined by geometrical and physiological constraints associated with body size, with small species of ladybird able to lay eggs at lower aphid population densities than large species. Cannibalism is thought to be the mechanism by which these predators are able to coexist.     

Niche overlap and interspecific association between Chilo partellus and Chilo orichalcociliellus on the Kenya coast

The use of felt traps to estimate oviposition by the cabbage root fly, Delia radicum (L.), and turnip root fly, Delia floralis (Fall.), was compared with soil sampling at seven localities between 1992 and 1994 in Denmark and Norway. In all, 281 comparisons were made, based on 6800 samples. In 4.6% of these comparisons no eggs were found by either method. In 16% of the comparisons, 2.0±0.41 (±S.E.) eggs were found per soil sample and no eggs were found in felt traps, whereas in 0.7% of the comparisons 0.10±0.03 eggs were found per felt trap and no eggs in soil samples. When eggs were found using both methods, the ratio between soil sampling and felt traps varied from 13.1±3.2 when the egg laying rate was very low to 1.8±0.2 at high egg laying rates. Regression analysis showed significant correlation between felt trap catches and soil sampling (P<0.001), whereas locality did not influence felt trap efficiency (P=0.096). The influence of the physical conditions of felt traps, i.e., whether they were clean and dry, were analysed in a single year. Tentative action thresholds for control measures against cabbage root flies and turnip root flies were developed for cauliflower, Brassica oleracea, convar. botrytis (L.) Alef., var. botrytis, based on data from the literature and the present results.