逐步回归模型在红棕象甲预测中的应用

红棕象甲[Rhynchophorus ferrugineus(Oliver)]是我国危害棕榈科植物的重要入侵害虫。2008年3月至2011年1月,以文昌市45块受红棕象甲危害的椰林为试验地,应用线性逐步回归分析的方法 ,组建了以土壤含水量、主林层郁闭度、土壤瘠薄程度和林龄为参数的红棕象甲发生量的预测模型。该模型通过实际检验,具有较高的预测功能,今后可在林业生产实际中加以应用。     

嗜菌异小杆线虫H06品系对红棕象甲幼虫的室内致死能力测定

为探讨利用昆虫病原线虫嗜菌异小杆线虫H06品系防治红棕象甲的可行性,在室内研究了该线虫对红棕象甲幼虫的致死效果和毒力水平。采用微量点滴法测试线虫不同施药剂量和施药时间对红棕象甲3龄幼虫的致病效果,并观察处理后红棕象甲幼虫的形态学特征变化。嗜菌异小杆线虫H06品系对红棕象甲具有一定的致死作用,随着线虫接种剂量的增加,红棕象甲死亡率增加;毒力测定结果显示,随着处理时间的延长,红棕象甲幼虫的LD₅₀呈现降低的趋势,同时随线虫接种剂量的提高,LT₅₀逐渐缩短;形态学观察结果显示,红棕象甲幼虫被嗜菌异小杆线虫H06品系感染后,虫体呈现出僵硬皱缩、体色变褐、身体肿胀直至最后虫体腐烂、线虫游离而出的现象。实验结果表明,嗜菌异小杆线虫H06品系对红棕象甲低龄幼虫具有一定的防控潜力。     

Development of a bioacoustic sensor for the early detection of Red Palm Weevil (Rhynchophorus ferrugineus Olivier)

The Red Palm Weevil (Rhynchophorus ferrugineus Olivier) is one of the worst pests for palms, since it can completely destroy the plant. Its early detection is very difficult and when the action of the pest is discovered, normally it is too late for recovering the plant. Bioacoustic sensors provide a good alternative for early detection of this pest because larvae activity is audible while they excavate tunnels to feed. This work describes the different stages for the development of an original electronic device based on acoustic sensors for early detection of Red Palm Weevil larvae in the interior of palms. This device is based on characteristic frequencies possibly related to their feeding activity. The performed tests have demonstrated that is possible to detect two week old larvae activity studying the sound intensity around 2250 Hz in palms infested only with 5 individuals under controlled environmental conditions. The activity of other insects artificially situated in the interior of palms did not affect the response of the device, possibly because they produce different frequencies (in the range 5–7 kHz). Future work will be aimed at assessing the infestation levels.     

Determination of the optimum sterilizing radiation dose for control of the red date palm weevil Rhynchophorus ferrugineus Oliv. (Coleoptera: Curculionidae)

The optimum dose of gamma radiation for sterilizing the red date palm weevil was determined using newly emerged weevils obtained from colonies established on four date palm cultivars in the laboratory. Male weevils from each date palm cultivar were treated with gamma radiation doses of 10, 15, 20, 25 or 30 Gray (Gy) and then mated with similar aged females to determine egg hatchability and male lifespan. Hatchability percent was significantly reduced at 15 Gy and above, and male lifespan was decreased at 10–15 Gy and above. Date palm cultivar significantly affected average male lifespan as well as egg hatchability, and the interaction between radiation dose and date palm cultivar was significant for both parameters. These results indicate that 15 Gy of gamma radiation to be an optimum dose for sterilizing red date palm weevil.     

红棕象甲幼虫化学防治研究

针对红棕象甲的生物学特性,采用灌根法、灌淋法、打孔注药法和熏蒸法等化学防治方法对红棕象甲幼虫进行了野外防治试验.结果表明,防治效果依次为:熏蒸法＞打孔注药法＞灌淋法＞灌根法.用磷化钙以每株树9.6g的剂量进行根部熏蒸,5d后防效达83.03％,可在生产中推广应用.     

Impact of area-wide malathion on predatory arthropods and secondary pests in cotton during boll weevil eradication in Texas

The boll weevil, Anthonomus grandis grandis, has been eradicated from much of the cotton producing region of the US and to-date eradication efforts continue in Texas. While providing long-term economic and environmental benefits, area-wide applications of malathion used by the eradication program have been implicated in the disruption of biological control of some cotton pests. This study evaluated the impact of the area-wide boll weevil eradication on abundance of predatory arthropods and key pests of cotton during four years in central Texas. Multiple applications of malathion ULV significantly reduced seasonal mean densities of spiders, predatory bugs (Orius spp. Pseudatomoscelis seriatus, Nabis spp., Geocoris spp.), Chrysopidae larvae and red imported fire ant, Solenopsis invicta, collected from the cotton canopy. In contrast, densities of beet armyworm, Spodoptera exigua, heliothine and other lepidopteron larvae, cotton aphid, Aphis gossypii, and adult and larval convergent lady beetle, Hippodamia convergens, often increased in cotton fields under boll weevil eradication. The density of total predators measured during the mid-season (period of blooming and early boll development) was significantly and negatively correlated with density of beet armyworm larvae during the late-season (boll maturation period). Results suggest that the community of predatory arthropods in the cotton canopy, rather than one or several key predators, is important in suppressing outbreaks of S. exigua and other lepidopteran pests in cotton. Furthermore, the potential to use densities of generalist predators in mid-season to anticipate late-season outbreaks of beet armyworm during boll weevil eradication is discussed.     

Assessing the impact of areawide pheromone trapping,pesticide applications,and eradication of infested date palms for Rhynchophorus ferrugineus (Coleoptera: Curculionidae) management in Al Ghowaybah,Saudi Arabia

The red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) is a highly destructive pest of date palms, Phoenix dactylifera L. (Arecales: Arecaceae), in Saudi Arabia. Data spanning a six year period (2007–2012) from Al Ghowaybah, a 1104 ha date producing region in the Al Ahsaa Directorate in Saudi Arabia, were analyzed to assess the impact enhanced management efforts that commenced in Oct. 2009 had against this pest. Within six months of initiating the areawide management program significant reductions in the mean monthly number of weevils trapped and percentage traps with R. ferrugineus were detected. Mean monthly trap captures of R. ferrugineus and the percentage of traps capturing weevils declined significantly from 2009 to 2012 by an average of 65% and 90%, respectively, indicating that trapping and dispersal pressure was significantly reduced. By 2011, average monthly trap captures and percentage of traps with R. ferrugineus were significantly lower than all pre-management capture data and this was maintained through 2012 when data collection ceased. Additionally, over the period 2010–2012, insecticide application and palm eradication rates dropped by 91% and 89%, respectively. The total number of R. ferrugineus captured in 2012 declined by 86% when compared to total captures for 2010. At the end of 2012, the estimated infestation rate of date palms in Al Ghowaybah was 0.36%, which was below the economic threshold of a 1% infestation rate set by the Directorate of Agriculture supervising the program. It is concluded that the mandatory areawide management program that commenced in Oct. 2009 against R. ferrugineus in Al Ghowaybah had a significant and rapid impact against this pest.     

First Report of Oryctes rhinoceros nudivirus (Coleoptera: Scarabaeidae) Causing Severe Disease in Allomyrina dichotoma in Korea

Oryctes rhinoceros nudivirus (OrNV) has been known to cause severe disease in coconut palm rhinoceros beetle, Oryctes rhinoceros, in Southeastern Asia and is used as a biological control to reduce the pest population. Here, we report for the first time that the OrNV may have landed on Korea and may be the major pathogen for diseased larvae of Korean horn beetle, Allomyrina dichotoma. After peroral inoculation, over 60% of infected larvae perished in 6 wk. This viral disease spreads very fast in several locations throughout Korea. This threat not only makes economic loss of local farms rearing A. dichotoma larvae but also may disturb the ecosystem by transmitting to wild A. dichotoma.     

Influence of phosphorus and potassium fertilization on damage to alfalfa,Medicago sativa L., by the alfalfa weevil,Hypera postica (Gyllenhall) and potato leafhopper,Empoasca fabae (Harris)

In a field study, the effects of phosphorus and potassium fertilization on damage caused by the potato leafhopper, Empoasca fabae (Harris), and alfalfa weevil, Hypera postica (Gyllenhall), to alfalfa, Medicago sativa L., were studied. Potato leafhopper and alfalfa weevil populations were either controlled with insecticides or allowed to develop as untreated controls. Insect management treatments were applied to alfalfa managed under high and low soil fertility regimes. Alfalfa grown under high soil fertility appeared more favourable for alfalfa weevil populations but was able to tolerate more defoliation. Populations of alfalfa weevil larvae were 34% higher on fertilized stands. On the other hand, potato leafhopper populations were as much as 43% higher on low-fertility stands. Alfalfa weevil damage caused a carry-over effect which reduced both plant height and yield of the second cutting. Fertilization negated this effect on height but not on yield. Stands damaged by potato leafhopper recovered more slowly after harvest, but fertilization reduced this effect. Yields from first-cutting alfalfa (which is not infested by the potato leafhopper) the following year were 10% greater on fertilized stands where leafhopper control had been applied the previous season. Plots infested by potato leafhopper suffered greater yield losses under low-fertility management. Leafhopper control and fertilization, alone and in combination with one another, negated these effects.     

几种引诱物对红棕象甲的诱集和田间监测

应用四臂嗅觉仪室内测定5种引诱物对红棕象甲成虫的嗅觉反应。结果表明,5种试验材料对试虫有一定引诱作用,其中聚集信息素、活雌虫和甘蔗诱集效果最明显。田问诱集试验结果表明,聚集信息素、活雌虫和甘蔗对红棕象甲成虫有好的大田诱集作用,菠萝和假槟榔田间诱集效果不明显。种群动态监测结果表明,红棕象甲在海南文昌地区,1 a有4次发生高峰期。      

Control of foliar diseases by the axillary application of systemic fungicides in Brazilian coconut palms

Endemic fungal foliar diseases, such as leaf blight – LB [Lasiodiplodia theobromae (Pat.) Griffon and Maubl] and leaf verrucosis, or “lixa-pequena” – LP [Camarotela torrendiela Batista (Bezerra) and Vitoria], reduce the productivity of the coconut palm in Brazil. Damage arises from extensive necrosis of the leaflets, resulting in early abscission of basal leaves and fruit. In Brazil, fungicide terrestrial sprayings has not been a commonly employed practice for the control of coconut foliar diseases because it is not cost-effective, once requiring high-volume of fungicide spraying. Coverage gaps and extensive drift of chemicals can occur due to technological limitations of terrestrial spraying of the tallest mature trees and is further complicated by the peculiar architecture of the palms. The aim of this study was to evaluate the efficacy of systemic fungicides applied directly to the leaf axil of the coconut palm (variety Brazilian Green Dwarf of Jiqui) for the control of foliar diseases. During 2007–2010 and 2009–2012, two field plot experiments were conducted at distinct locations (farms) in the North Fluminense region. Two to 4-monthly applications of the fungicides to the leaf axil of cyproconazole (alone), cyproconazole plus azoxystrobin, cyproconazole plus trifloxystrobin, and flutriafol (alone) were efficacious in controlling coconut palm leaf diseases, resulting in a significant reduction of the LB severity and the number of necrotic LP lesions. When compared with the control treatment, significant increases in the total number of leaves per plant were observed for the most efficacious treatments after one year (2–4 leaves more) and after the second year (3–6 leaves more) after initiating the axillary applications of fungicides in both experiments. This trend continued even after the third year, when there was an average of 8 leaves more for the most efficacious treatment (27 leaves per plant) compared to control (19 leaves per plant) at the end of second experiment. The control of foliar diseases based on the results could ensure a significant increase in regional coconut production.     

Variation in C:N:S Stoichiometry and Nutrient Storage Related to Body Size in a Holometabolous Insect (Curculio davidi) (Coleoptera: Curculionidae) Larva

Body size can be an important factor controlling consumer stoichiometry. In holometabolous insects, body size is typically associated with nutrient storage. Consumer stoichiometry is known to vary within species across a range of body sizes; however, the contribution of nutrient storage to this variation is not well understood. We used the fifth-instar larvae of the oak weevil (Coleoptera: Curculio davidi Fairmaire), which is characterized by a high capacity for nutrient storage, to investigate the effect of shifts in nutrient storage with body mass on variations in larva stoichiometry. Our results showed that weevil larvae with larger body mass had a lower carbon (C) content, reflecting decreases in the sequestration rate of C-rich lipids. Larger larvae had elevated concentrations of nitrogen (N), sulfur (S), and protein. The similar patterns of variation in elemental composition and macromolecule storage with body weight indicate that the shift in nutrient storage is the main factor causing the variation in larval stoichiometry with body weight. This finding was further supported by the low variation in residual larval biomass C, N, and S concentrations after lipid extraction. These results help decipher the physiological mechanism of stoichiometric regulation in growing organisms.     

Evaluation of augmentative release of Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) for biological control of Parthenium hysterophorus L.

Augmentative release of biocontrol agents has been largely successful for the management of insect pests but it has not been a common approach for weed management. Augmentation methods need to be developed for weed management, especially for pernicious weeds like Parthenium hysterophorus L., commonly known as pathenium or carrot weed. The leaf beetle Zygogramma bicolorata is a potential biocontrol agent of P. hysterophorus. Initial release of biocontrol agents is subject to uncertainties as to whether timely population built-up will take place in sufficient numbers. Several augmentative releases may be required to ensure early establishment of the biocontrol agents, for successful biological control of noxious weeds including pathenium. We made augmentative releases of larvae or adults of Z. bicolorata each to three sites, severely infested with pathenium at Jabalpur, India consecutively for a period of three years. Initially 10 larvae or adults per sq m were released in each plot, followed by a second, third and fourth release of 3, 1.5 and 1.5 larvae or adults per sq m at an intervals of 3, 7 and 14 days after the first augmentation. The pathenium at augmented sites were completely defoliated in 45 and 60 days by larvae and adults respectively. There was also a reduction in the pathenium density and plant height in the augmented sites as compared to the non-augmented sites. Over a period of 3 years augmentation resulted in a noteworthy negative effect on the weed.     

三亚市椰心叶甲寄生蜂的防效调查

先后2次对海南三亚市椰心叶甲放蜂点进行寄生蜂防治效果调查,从放蜂点分布、椰树危害程度、虫口密度和寄生蜂寄生率等4个方面评价椰心叶甲啮小蜂和椰甲截脉姬小蜂对椰心叶甲的防控效果。结果表明：三亚的椰树危害程度在逐渐减轻,轻度危害的椰树已占调查点的60％,虫口密度已明显下降。从两种寄生蜂的分布情况来看,椰心叶甲啮小蜂在三亚的分布范围在扩大,已经分布在每个调查点,椰甲截脉姬小蜂的分布范围则略有缩小。两种寄生蜂的寄生率比较来看,椰心叶甲啮小蜂较2007年高,而椰甲截脉姬小蜂在三亚的寄生率较2007年差。说明了两种寄生蜂均可以在三亚寄生生存,椰心叶甲啮小蜂在三亚的生存能力更强,对椰心叶甲的防控效果比椰甲截脉姬小蜂好。本研究对如何利用寄生蜂来控制椰心叶甲,具有重要的参考意义。     

Body Size Plasticity of Weevil Larvae (Curculio davidi) (Coleoptera: Curculionidae) and Its Stoichiometric Relationship With Different Hosts

Parasites obtain energy and nutrients from the host, and their body size is also usually limited by host size. However, the regulatory mechanisms that control the plasticity of parasite body sizes and the stoichiometric relationships with their hosts remain unclear. Here we investigated the concentrations of 14 elements (C, H, O, N, P, S, K, Na, Ca, Mg, Al, Fe, Mn, and Zn) in the acorns of three oak species (Quercus spp.), in their endoparasitic weevil (Curculio davidi Fairmaire) (Coleoptera: Curculionidae) larvae and in the larval feces, and the weight of weevil larvae within different hosts in a warm-temperate zone of China. Our results showed that the three acorn species exhibited significant differences in C, H, O, P, K, Mg, and Mn concentrations. However, in the weevil larvae, only P, Mn, and C:P ratio revealed significant differences. Weevil larvae preferentially absorbed and retained N, Zn, Na, and P, whereas Mn, K, Ca, and O were passively absorbed and transported. The weevil larvae weight was associated with acorn stoichiometry, and positively correlated with acorn size. Weevil larvae P decreased, but Mn and C:P increased with their weight, implying highly variable in somatic stoichiometry are coupled with the plasticity of body size. Interestingly, weevil larvae weight was negatively correlated with acorn infection rate, indicating small-size parasitic insects might have higher fitness level in parasite–host systems than larger-size ones. Our results suggest that variation in P, Mn, and C:P in parasites may play critical roles in shaping their body size and in improving their fitness.     

Abundance of Sitona lineatus L. (Col., Curculionidae) in peas (Pisum sativum L.): Effects on yield parameters and nitrogen balance

In a four-year study, we investigated the relationship between the damage to root nodules of organically produced pea (Pisum sativum L.) by the larvae of the pea leaf weevil (Sitona lineatus L.) and the abundance of adult weevils. In addition to studying natural infestations, we established artificial infestations within cages to assess the impact of different weevil densities on yield parameters and determinants of the nitrogen balance. Densities of 0.2 adult S. lineatus per plant (20 individuals per m²) reduced the number of seeds and pods per plant by 18% and 15%, respectively; seeds per pod and thousand-seed weight remained unaffected. A three-fold or five-fold increase in weevil abundance (13–40 or 20 to 100 individuals per m²) did not result in an additional reduction in yield. Moreover, the higher weevil abundance did not adversely affect the N-harvest index or soil nitrogen content. We suspect that the impact of adult S. lineatus on yield and nitrogen parameters is limited by the density-dependent mortality of the larvae. Survival of larvae in turn depends on the nodulation of the plants, which is largely regulated by the supply of water. The assumption that organic cropping systems are at specific risk from the pea leaf weevil was confirmed by increasing population densities during the study period. However, yield losses were independent of adult attack within a wide range of weevil abundance, which indicates the complexity of assessing larval damage based on adult infestation level. An enhanced intraspecific competition among larvae may account for the absence of linear relationships, considering that especially young instars failed to establish in root nodules at higher densities. We found that adult densities of 0.2 individuals per plant and subsequent larval densities of 7 individuals per plant resulted in destruction of 37% of the root nodules on primary roots, which was much below destruction values reported in other studies. In conclusion, we recommend an early monitoring of weevils and early initiation of control strategies because yield losses were caused by even low weevil densities. Finally, the tolerance of P. sativum to S. lineatus was influenced by the yield level, i.e., tolerance to S. lineatus decreased as yield increased.     

Evaluation of neonicotinoids as pyrethroid alternatives for rice water weevil management in water-seeded rice

The rice water weevil (RWW), Lissorhoptrus oryzophilus (Kuschel) (Coleoptera: Curculionidae), is the most destructive insect pest of rice in the United States. Water-seeded rice, which is flooded at an earlier stage of crop development than drill-seeded rice, is at heightened risk of loss from root-feeding RWW larvae. Pyrethroids, the most widely used group of foliar insecticides for RWW control, have inherent limitations such as limited residual activity, narrow window of activity and extreme toxicity to non-target aquatic organisms. An array of field, lab and greenhouse experiments was conducted to compare the activity of two neonicotinoids with that of λ-cyhalothrin, a widely used pyrethroid, against the RWW. Small-plot efficacy trials were conducted during 2009, 2010 and 2011. Foliar clothianidin (Belay 2.13 SC) and a granular formulation (3%) of dinotefuran applied to plots were as effective as, and showed greater residual activity than, foliar applications of λ-cyhalothrin. Topical bioassays on adult weevils revealed that clothianidin possessed lower contact toxicity than λ-cyhalothrin. Residual assays using weevils placed on foliage of sprayed plots revealed that the toxic and sublethal behavioral effects of clothianidian on adult weevils were more persistent for clothianidin than for λ-cyhalothrin. Granular dinotefuran applied to greenhouse-grown plants previously infested with weevil larvae showed excellent larvicidal activity. Overall, these studies showed that neonicotinoids have potential as pyrethroid replacements against the RWW in water-seeded rice culture.     

Determination of oil palm fresh fruit bunch ripeness—Based on flavonoids and anthocyanin content

Non-destructive and real-time oil palm fresh fruit bunch (FFB) grading systems are of major exploratory concern for researchers in the oil palm industry. The objective is to reduce time, labour, costs, and most importantly, to increase the oil extraction rate, in order to achieve a good quality of palm oil at a more acceptable price. This research investigates the potential of flavonoids and anthocyanins as a predictor to classify the degree of oil palm FFB ripeness. This paper also discusses the relationship between these predictors and the ripeness categories period. One hundred and eighty oil palm FFB samples were collected from a private plantation in Malaysia, according to three maturity categories i.e., ripe, under-ripe, and over-ripe. Each sample was randomly scanned 10 times, both front and back using a hand-held Multiplex^®3 multi-parameter fluorescence sensor. The results show that flavonoid and anthocyanin content decreased from immature to over mature oil palm FFBs. Overall, the relationship using Pearson's correlation between flavonoids and anthocyanins was r² = 0.84 and the most outstanding relationship accuracy was at the over-ripe stage, at 90%. Statistical analysis using analysis of variance (ANOVA) and pair-wise testing proved that both predictors gave significance difference between under-ripe, ripe, and over-ripe maturity categories. This shows that both predictors can be good indicators to classify oil palm FFB. Classification analysis was performed by using both predictors together and separately through several methods. The highest overall classification accuracy was 87.7% using a Stochastic Gradient Boosting Trees model and with both predictors. The other classification methods used either independent or both predictors together and gave various results ranging from 50 to 85% accuracy. This research proves that flavonoids and anthocyanins can be used as predictors of oil palm maturity classification.     

Relative abundance and damage by target and non-target insects on Bollgard and BollgardII cotton cultivars

Bollgard^® and BollgardII^® cotton cultivars were evaluated for their efficacy for control of bollworms and their effects on sucking insects and the abundance of natural enemies under bollworm insecticide protected and non-insecticide protected field conditions during the 2004 and 2005 cropping seasons. Bollgard cultivars are genetic transforms that produce Cry1Ac toxins from Bacillus thuringiensis (Bt) to control American bollworm, Helicoverpa armigera. Second generation BollgardII cultivars contain 2 toxins, Cry1Ac and Cry2Ab, and are more effective in controlling a broader range of caterpillar species. Bollgard cultivars were free of H. armigera damage until harvest under insecticide protected as well as non-protected conditions. Both BollgardII and Bollgard cultivars were infested with larvae of spotted bollworm, Earias vitella, and spiny bollworm, Earias insulana, at later crop growth stages. Neither BollgardII nor Bollgard cultivars were free of square (fruiting body), open boll and loculi damage. Bollworm damage did not reach economic threshold levels up to harvest. Densities of sucking insects (Amrasca biguttula biguttula, Bemisia tabaci, Aphis gossypi, and Thrips tabaci), of the foliage feeder Myllocerus undecimpustulatus and of predators (Chrysoperla spp., Orius spp., Coccinella spp., Brumus spp., Vespa spp., Lycosa spp., and Aranews spp.) were similar on Bollgard, BollgardII and conventional cultivars. The time of the first appearance of bollworms, sucking insects and predators on Bt cotton did not vary from conventional cotton varieties. Insecticidal protection based on economic threshold levels resulted in significant reductions in bollworm damage on conventional cultivars.