Egg load and adaptive superparasitism in Anaphes nitens, an egg parasitoid of the Eucalyptus snout-beetle Gonipterus scutellatus

We studied egg production and the occurrence of adaptive superparasitism in Anaphes nitens, an egg parasitoid of the Eucalyptus snout beetle Gonipterus scutellatus. First, we determined whether A. nitens females were synovigenic or pro‐ovigenic. Newly emerged females were allowed to lay eggs alone during 3 days on six fresh egg capsules. A first group of females (n = 25) were killed by freezing and the remaining females (n = 21) were maintained during two extra days with food, but without hosts. Their fecundity was measured by dissection of host eggs and females’ ovarioles. We found that the second group of females increased their fecundity by about 20%, suggesting they were weakly synovigenic. To test for the occurrence of adaptive superparasitism in relation to competitors’ density, we compared the oviposition behaviour of females kept alone, in pairs, or in groups of four during patch visit. Results indicated that the females superparasited significantly more often in this last treatment. Synovigeny and the ability to modulate the use of superparasitism could be mentioned as important attributes that allow A. nitens to efficiently control the pest population.     

Life cycle and biological control of the Eucalyptus snout beetle (Coleoptera, Curculionidae) by Anaphes nitens (Hymenoptera, Mymaridae) in north-west Spain

1 Gonipterus scutellatus is a weevil that has become a pest in most Eucalyptus plantations in Africa, America and Europe. The egg parasitoid Anaphes nitens has been introduced into many countries as a biological control agent. Even if control has been successful in most countries no detailed study of the interactions between both species has been published. 2 Gonipterus scutellatus was detected in 1991 in north-west Spain and A. nitens was introduced in early 1994. Here we report on the results of a 2-year study of parasitism in a field plot and a survey of 16 localities in North-west Spain. In 1996, parasitism was so intense (80–100% of eggs) that G. scutellatus became locally extinct, and as a consequence A. nitens disappeared. In 1997, G. scutellatus recolonized the area and was followed by its parasitoid, but parasitism was low in spring, probably because the parasitoid population needed 3 weeks to achieve a similar size as in 1996. Consequently, damage to the trees was extreme in 1997. We interpret these results as population fluctuations due to parasitoid–host interactions and suggest that parasitoids should not to be so effective as to locally extinguish their host to be useful for biological control. 3 The analysis of parasitism level in 16 localities indicates that A. nitens is highly efficient in finding G. scutellatus egg-masses. At a small spatial scale (single trees) positive density dependence was detected where parasitism was low and inverse density dependence where parasitism was high.     

Phenology of Eucalyptus weevil, Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae), and chrysomelid beetles in Eucalyptus globulus plantations in south-western Australia

1 In south‐western Australia, Eucalyptus globulus plantations are defoliated by a complex of beetle species, yet only scant information exists on these species under such climatic conditions. To improve management of these defoliating beetles in the region, canopy fogging and shoot clipping were conducted in plantations between 1999 and 2002 to identify and document the phenology of the beetle species present. 2 Eucalyptus weevil, Gonipterus scutellatus, was the most common and destructive defoliating beetle. Gonipterus scutellatus undergoes one principal generation each year with a lesser second generation or cohort in some seasons, which contrasts greatly with reports of two to four annual generations for the species in other regions. This limited reproduction by G. scutellatus may be due to the limited availability from summer onwards of new flushing foliage, which is essential for feeding and oviposition. 3 Several species of chrysomelid beetles were collected in plantations, but these were present in much lower numbers than G. scutellatus and were only a minor concern. However, some species, such as Chrysophtharta variicollis, appear to be capable of developing short‐lived outbreaks. 4 A diverse suite of natural enemies was fogged from plantations but they were significantly less abundant than defoliating beetles and are not likely to provide significant control of beetles. 5 In terms of managing these defoliating beetles, monitoring and control should focus on G. scutellatus, and be conducted during spring when most damage occurs.     

Root and shoot elongation of rhizotron-grown seedlings of Eucalyptus nitens and Eucalyptus globulus in relation to temperature

Information on the growth response of a crop plant in relation to temperature can be helpful in selecting genotypes to suit local environments, scheduling favourable time of planting and forecasting growth and yield. To determine the effects of varying temperature on root and shoot elongation of eucalypt seedlings, elongation rates of roots and shoots were measured in rhizotrons for two species (Eucalyptus nitens (Deane and Maiden) Maiden, and Eucalyptus globulus Labill.) at a temperature range of 5–23 °C. Within this range of temperatures, elongation rates of roots and shoots of both species increased with an increase in temperature. Roots of E. globulus were more sensitive and shoots less sensitive to temperature than those of E. nitens. However, the threshold temperature corresponding with zero elongation rate predicted from the regression of elongation rate against temperature was similar for the roots (∼5 °C) and shoots (∼0 °C) of both species. Hysteresis did not appear to have a significant influence on root or shoot elongation of both species during warming compared with cooling. Results are discussed highlighting the importance of the interaction between development and growth of plant components.     

Identification and quantification of endogenous gibberellins in apical buds and the cambial region of Eucalyptus

Endogenous gibberellins (GAs) were extracted and purified from apical buds of Eucalyptus nitens (Deane and Maid.) Maid. and the cambial region of E. globulus (Labill.). then analysed by capillary gas chromatography-mass spectrometry. GA₁ GA₁₉ GA₂₀ and GA₂₉ were identified by full scan mass spectra. Kovats retention indices and high resolution selected ion monitoring. Using deuterated internal standards. GA₁. GA₁₉. GA₂₀ and putative GA₂₉ and GA₅₃ were quantified in the apical buds, while GA₄. GA₈. GA₉ and GA₄₄ were shown to be either absent or present at very low levels. From the cambial region. GA₁ and GA₂₀ were quantified at levels of 0.30 ng (g fresh weight)-¹ and 8.8 ng (g fresh weight)-¹ respectively. These data suggest that the early 13-hydroxylation pathway is the dominant pathway for GA biosynthesis in Eucalyptus .     

Assessment performance of Eucalyptus clones attacked by the recent invasion of Leptocybe invasa (Hymenoptera: Eulophidae): Implications to invasion pest management

Eucalyptus gall wasp, Leptocybe invasa is one of the most important invasive pests of Eucalyptus (Myrtaceae) and has been reported in new cultivation areas worldwide. This pest causes severe damage to susceptible plants of the genus Eucalyptus, where it induces galls in the midribs and petioles of young leaves and the internodes of branch and apices. In this work, we evaluated the response of Eucalyptus clones (E. urophylla (Urophylla) and two clone hybrids, one of the E. urophylla × E. camaldulensis (Urocam) and other of E. urophylla × E. grandis (Urograndis) crossings.) submitted to L. invasa collected from areas where L. invasa was recently reported. Our results show that the eucalypt materials cultivated in the areas where L. invasa were reported sensitive to L. invasa attacks. However, the wasp causes fewer galls in the Urocam clone. Thus, the Urocam clone can be preferred for use to reduce population growth of L. invasa in Brazilian savannah areas.     

Parallel evolution of dwarf ecotypes in the forest tree Eucalyptus globulus

Three small populations of a dwarf ecotype of the forest tree Eucalyptus globulus are found on exposed granite headlands in south-eastern Australia. These populations are separated by at least 100 km. Here, we used 12 nuclear microsatellites and a chloroplast DNA marker to investigate the genetic affinities of the dwarf populations to one another and to their nearest populations of tall E. globulus. Cape Tourville was studied in greater detail to assess the processes enabling the maintenance of distinct ecotypes in close geographical proximity. The three dwarf populations were not related to one another and were more closely related to adjacent tall trees than to one another. At Cape Tourville the dwarf and tall ecotypes were significantly differentiated in microsatellites and in chloroplast DNA. The dwarf and tall populations differed in flowering time and no evidence of pollen dispersal from the more extensive tall to the dwarf population was found. The three dwarf populations have evolved in parallel from the local tall ecotypes. This study shows that small marginal populations of eucalypts are capable of developing reproductive isolation from nearby larger populations through differences in flowering time and/or minor spatial separation, making parapatric speciation possible.     

Two new egg parasitoids (Hymenoptera: Encyrtidae) of the wood borer Agrianome spinicollis (Macleay) (Coleoptera: Cerambycidae), a pest of pecans in eastern Australia

Abstract Baeoanusia xanthopleuron sp. n. and Avetianella coombsi sp. n. (Hymenoptera: Encyrtidae) are described from New South Wales and Queensland. Photomicrographs are provided to illustrate morphological characters of both species, and their systematic position is discussed on the basis of their morphology and biology. Both species are egg parasitoids of the wood borer Agrianome spinicollis (Macleay), an important pest of pecans in eastern Australia.     

A method to assess the effects of pesticides on the predatory mite Phytoseiulus persimilis (Acari Phytoseiidae) in the laboratory

Phytoseiulus persimilis Athias-Henriot (Acari Phytoseiidae) is a major predator of Tetranychus urticae (Acari Tetranychidae). The performance of P. persimilis in controlling T. urticae may be altered by pesticides used to manage other pests. Therefore, knowledge of the side-effects of pesticides is essential for IPM. A number of laboratory methods were suggested to evaluate pesticide side-effects on predatory mites. Most methods assess residual effects only, and a number of them are characterised by high predator escape rates from experimental units. A method aimed at evaluating the topical and residual effects of pesticides on P. persimilis is herein described. Mites were treated by microimmersion and then reared in holding cells, on bean leaves previously dipped in a pesticide solution. Three insecticides (pyrethrins, spinosad and thiamethoxam), an insecticide-acaricide (abamectin), and two fungicides (azoxystrobin and tolylfluanide) were evaluated. The strain of P. persimilis used for evaluation was collected from unsprayed vegetable plants. All the pesticides affected the survival and fecundity of P. persimilis. Pesticides did not affect the egg-hatching of P. persimilis females exposed to pesticides. Pyrethrins and abamectin proved to be more toxic than other pesticides, and thiamethoxam was more toxic than spinosad, azoxystrobin and tolylfluanide. The escape rate from experimental units was lower than 5% in all trials. Additional experiments were performed on P. persimilis eggs by dipping leaves with eggs in the pesticide solution. None of the pesticides affected egg survival. Semi-field trials conducted on potted bean plants obtained results similar to those reported in laboratory trials.     

Differences in the response of carbon assimilation to summer stress (water deficits, high light and temperature) in four Mediterranean tree species

Daily changes in photoprotective mechanisms were studied in sun leaves of Quercus suber L., Quercus ilex L., Olea europaea L. and Eucalyptus globulus Labill. trees during the summer in Portugal. Even though stomatal closure explained most of the diurnal variation in carbon assimilation along the summer, a decline in the photochemical yield of photosystem II (F'v/F'm) also occurred, as a result of an excess of intercepted solar radiation when carbon assimilation is limited by stomatal closure due to high vapour pressure deficits and/or soil water deficits. These changes were accompanied by the conversion of violaxanthin to antheraxanthin and zeaxanthin which were correlated with thermal dissipation of excess photon energy. In spite of a common general response, differences between species were observed Olea europaea , which is a slowgrowing tree, had the lowest net photosynthetic rates, the highest proportion of carotenoids in relation to chlorophyll and the highest rates of deepoxidation of violaxanthin. This enabled a large thermal dissipation of the excess intercepted radiation but led to rather small values of light utilisation for photochemistry (ca 20%). In contrast, in E. globulus , a fastgrowing tree, photosynthetic rates were the highest, thermal dissipation of absorbed radiation the lowest and maximal values of light utilisation for photochemistry reached ca 50%. The two Quercus species exhibited an intermediate response. A high degree of coordination is apparent between stomatal behaviour, photosynthetic capacity and photoprotection mechanisms.     

Evaluation of biorational insecticides and DNA barcoding as tools to improve insect pest management in lablab bean (Lablab purpureus) in Bangladesh

Lablab bean (Lablab purpureus) is a popular vegetable crop in Bangladesh, but farmers growing this crop experience significant losses to insect pests despite heavy reliance on conventional insecticides. We conducted field studies to improve pest management in lablab bean by testing biorational insecticides as alternatives to conventional insecticides for the control of pod borers (Maruca vitrata) and aphids (Aphis craccivora), and characterizing flower-inhabiting thrips as an emerging pest in this crop. In field experiments, spinosad was the most promising biorational we tested, suppressing pod-boring caterpillars more effectively than thiamethoxam or quinalphos. In contrast, azadirachtin (neem) did not significantly suppress any of the insect pests we measured, although target aphid populations were generally low at our research site. Using DNA barcoding at the coxI locus combined with morphological identification, we found eight thrips taxa inhabiting lablab bean flowers, dominated by Megalurothrips usitatus and M. distalis/peculiaris. A preliminary regression analysis indicated that these flower-inhabiting thrips reduced lablab bean yield. Our results suggest that spinosad may be useful within lablab bean IPM programs, and that these programs will likely need to incorporate tactics against thrips to effectively protect yield. Finally, we found that DNA barcoding was a valuable tool for pest identification in an understudied crop and region, but that to reach its full potential will require an investment in more comprehensive reference libraries.     

电导率与极端低温分布在闽中桉树引种决策上的研究

依据闽中地区永安市1971～2005年的极端低温与极值分布数学模型和气象学原理,探讨5～10 a内该区域不同海拔高度可能出现的极端异常低温,利用电导率测定引种区所引种的不同抗寒程度的桉树种的半致死温度,事前评价引种的可行性.首次提出利用极端低温与电导率进行引种决策,并把该方法称作"极端环境反应法".结果表明:在出现10 a以上异常低温时,邓恩桉(Eucalyptus dunnii)在该区域垂直分布可达海拔775 m,巨桉(E.grandis)及相近抗寒能力的桉树可在海拔467 m以下栽植,赤桉(E. camaldulensis)可在海拔960 m以下栽植.该方法可广泛应用于其它区域与不同树种引种的事前评价与决策.     

Prospects of botanical pesticides for the future in integrated pest management programme (IPM) with special reference to neem uses in Egypt

Botanically derived insecticides have gained favour in recent years. They are more safe or natural. Also, they are comparatively safe to natural enemies and higher organisms. Neem, pyrethrum, rotenone, nicotine, sabadilla, ryania and a number of different available botanicals were used to protect agricultural crops from the ravages of insects, mites and nematodes in different parts of the world. In Egypt, experiments were carried out on the efficacy of neem seed kernel extract fractions and formulations against different pests. Promising results were obtained showing feeding deterrency, repellency, toxicity, sterilant and growth disruptive activities. However, few of these can be exploited as crop protectants. Those that are proven to have sufficient efficacy against pests in the field and can be produced in adequate quantities are suitable candidates for commercial development.     

Toxicity assessment of insecticides commonly used in rice pest management to the fry of common carp, Cyprinus carpio, a food fish culturable in rice fields

Toxicity of four insecticides commonly used in rice pest management, chlorpyrifos, dimethoate, carbaryl and carbosulfan, to the fry of common carp was assessed through median lethal concentrations (LC₅₀) and in vivo inhibition of the brain acetylcholinesterase (AChE) enzyme at sublethal concentrations. The 96‐h LC₅₀ values for these four insecticides were determined to be 0.008, 26.11, 7.85 and 0.60 mg L^?1 respectively. Exposure of fish to a series of sublethal concentrations (0.5–5% LC₅₀) of each insecticide for 14 days resulted in concentration‐dependent inhibition in AChE activity in comparison with the controls. AChE activity was greatly inhibited in the fish exposed to sublethal concentrations of chlorpyrifos. Upon transfer to insecticide‐free water, AChE activities in fry exposed to 0.5 and 1% LC₅₀ concentrations of carbaryl and carbosulfan were restored to the control level within 7–21 days whereas the fish exposed to chlorpyrifos or dimethoate did not fully recover from the insecticide‐induced anticholinesterase action. Of the four insecticides tested, chlorpyrifos was the most toxic for the fry of common carp. Although dimethoate was least toxic for the fish under acute exposure, the restoration level of normal AChE activity was slower under chronic exposure in comparison with carbaryl and carbosulfan. Hence, the use of carbamates, especially carbaryl, to control insect pests of rice in rice‐cum‐carp culture systems is recommended when considering survival, restoration of the normal AChE activity and stamina of the cultured fish.     

Double sampling to assess the accuracy of ground‐based surveys of tree hollows in eucalypt woodlands

Ground‐based surveys of tree hollows often give poor estimates of hollow abundance in forests. Woodlands have shorter trees and a more open structure than forests, which may make hollows easier to detect. Therefore, one would expect ground‐based surveys of tree hollows to be more accurate in woodlands than in forests. We compared hollow counts from ground‐based and climbing surveys (double sampling) for four species of Eucalyptus trees in woodlands of central‐western New South Wales, Australia: E. camaldulensis Dehnh, E. melliodora A. Cunn. ex Schauer, E. microcarpa Maiden and E. populnea F. Muell. ssp. bimbil L.A.S. Johnson & K.D. Hill and E. melliodora A. Cunn. ex Schauer. Overall, 83% of hollow‐bearing trees and 93% of trees without hollows were correctly classified by ground‐based surveys. Mean difference in hollow counts of ground‐based surveys to climbed surveys was 1.7 hollows ± 0.2 SE (all species combined) with 91% of ground‐based hollow counts being within five of the actual number of hollows. The error in ground‐based counts of hollows in E. microcarpa was larger than for the other three species. Errors in all species resulted from both overestimation and underestimation of hollow abundance by ground‐based surveys. A larger error was associated with the detection of hollows located in branches compared with hollows located in the main trunk(s). Total number of hollows in the tree (based on climbing surveys), crown area or maximum trunk diameter were significant predictors of ground‐based survey accuracy. Overall, the accuracy associated with ground surveys was relatively high and generally error rates were lower than those published for forests.     

西班牙桉树林下土小平盘菌复合群中两个独立的种——暗柔膜菌属一新组合及一新种:分类、分子生物学、生态与分布(英文)

土小平盘菌复合群原产澳大利亚,其中两个土生种在西班牙报道,很可能是在18世纪中叶引入西班牙。根据形态学特征和序列分析的结果,建立一个新组合和一个新种,分别定名为Phaeohelotium undulatum comb.nov.和Phaeoh.succineoguttulatum sp.nov.。对其宏观和微观形态特征进行了详尽的描述和图示,ITS rDNA序列分析的结果显示,它们以100%的支持率与Phaeohelotium monticola聚类在同一个分支。文中提供了该复合群Phaeohelotium属5个土生种的分种检索表,并对它们的生态习性与世界分布进行了深入讨论。     

Acclimation of snow gum (Eucalyptus pauciflora) leaf respiration to seasonal and diurnal variations in temperature: the importance of changes in the capacity and temperature sensitivity of respiration

We investigated the relationship between daily and seasonal temperature variation and dark respiratory CO₂ release by leaves of snow gum (Eucalyptus pauciflora Sieb. ex Spreng) that were grown in their natural habitat or under controlled‐environment conditions. The open grassland field site in SE Australia was characterized by large seasonal and diurnal changes in air temperature. On each measurement day, leaf respiration rates in darkness were measured in situ at 2–3 h intervals over a 24 h period, with measurements being conducted at the ambient leaf temperature. The rate of respiration at a set measuring temperature (i.e. apparent ‘respiratory capacity’) was greater in seedlings grown under low average daily temperatures (i.e. acclimation occurred), both in the field and under controlled‐environment conditions. The sensitivity of leaf respiration to diurnal changes in temperature (i.e. the Q₁₀ of leaf respiration) exhibited little seasonal variation over much of the year. However, Q₁₀ values were significantly greater on cold winter days (i.e. when daily average and minimum air temperatures were below 6° and –1 °C, respectively). These differences in Q₁₀ values were not due to bias arizing from the contrasting daily temperature amplitudes in winter and summer, as the Q₁₀ of leaf respiration was constant over a wide temperature range in short‐term experiments. Due to the higher Q₁₀ values in winter, there was less difference between winter and summer leaf respiration rates measured at 5 °C than at 25 °C. The net result of these changes was that there was relatively little difference in total daily leaf respiratory CO₂ release per unit leaf dry mass in winter and summer. Under controlled‐environment conditions, acclimation of respiration to growth temperature occurred in as little as 1–3 d. Acclimation was associated with a change in the concentration of soluble sugars under controlled conditions, but not in the field. Our data suggest that acclimation in the field may be associated with the onset of cold‐induced photo‐inhibition. We conclude that cold‐acclimation of dark respiration in snow gum leaves is characterized by changes in both the temperature sensitivity and apparent ‘capacity’ of the respiratory apparatus, and that such changes will have an important impact on the carbon economy of snow gum plants.     

Seasonal variation in susceptibility of the pear psyllid,Cacopsylla permixta (Hemiptera: Psyllidae) to selected insecticides

Although Cacopsylla pyri Forster and Cacopsylla pyricola Linnaeus have long been considered as more significant pests of pear trees around the world, Cacopsylla permixta Burckhardt and Hodkinson is the most significant pest in some parts of Iran, especially in pear gardens of Karaj. Current control strategies against this pest in Iran generally involve five or six insecticide treatments each year, despite unsatisfactory results are reported at many localities. So, it is crucial to know the most susceptible generation of the pest to apply a good strategy for its control. The aim of this study was to explore the seasonal variation in susceptibility of C. permixta to four commonly used insecticides. The results showed that winter forms (February) were 2.71‐fold, 4.58‐fold, 3.26 fold and 3.38‐fold more tolerant to diazinon, imidacloprid, acetamiprid and abamectin, respectively, compared with summer forms. Also, Esterase, GST and P450 monooxygenase activity was highest during February. Moreover, the content of lipid, carbohydrate, glycogen and protein was significantly higher in February compared with other months. Based on these results, the best period for insecticide treatment for efficient control is treatment against the first generation, at the time when eggs are laid by females as well as during the egg hatching and the larvae appearance. At this time of year, psylla are more susceptible, which would likely lead to better results and the reduction in damage during the next summer. However, further studies are needed to test this in farm settings, and to whether this holds true for other psylla species.     

Development and application of an integrated pest management programme for the psyllid,Ctenarytaina thysanura onBoronia megastigma in Tasmania

An integrated pest management programme for control of the psyllid,Ctenarytaina thysanura (Ferris & Klyver) (Hemiptera: Psyllidae) in commercial boronia plantations was developed and implemented from 1986–1989. The programme involved spraying boronia stems only with the systemic organophosphate mevinphos at peak incidence of late stage nymphs. At this time, the majority of parasitoids were pupating within mummified hosts. Consequently, actively feeding nymphs were potentially susceptible to mevinphos but the parasitoids were not. Stem application negated any contact effect on parasitoids and predators. The conservation of natural enemies subsequently reduced psyllid numbers and no insecticide has been required since 1989. In economic terms the benefit to cost ratio of the IPM programme was $22.40: $1.0 and this was 40 times greater than the conventional 10 demeton-S-methyl sprays used by growers prior to the study.