Pink bollworm of cotton (Pectinophora gossypiella (Saunders)): male moth catches in gossyplure-baited traps and relationships to oviposition, boll infestation and moth emergence

Pheromone-baited traps are an important sampling tool in integrated pest management programmes. Studies were conducted to determine the relationship between catches of male insects in these traps, and crop infestation. Numbers of male moths of the pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), caught daily in cotton fields at the University of Arizona Cotton Research Center, Phoenix, Arizona, in gossyplure-baited traps were variable. However, average catches of male moths for 3–7 days between boll-sampling periods were strongly correlated with oviposition on cotton bolls, percentages of infested bolls and numbers of larvae per boll. Average weekly numbers of moths emerging from infested cotton were also strongly correlated with the number of males caught: the number of females emerging was strongly correlated with oviposition on cotton bolls. Insecticide applications of carbaryl and fenvalerate reduced catches of male moths of pink bollworm in gossyplure-baited traps compared with catches in traps in untreated fields (average 56%). However, 13–48 male moths/trap per night were caught in the treated fields after applications. Thus, scheduling treatments on the basis of male moth trap catches, except for the initial treatment, was not feasible. Small field sizes, moth immigration and/or continuing emergence from the infested cotton in the fields may have obscured the impact of the insecticide treatments on adult moth populations.     

The potential for pheromone-based monitoring to predict larval populations of diamondback moth,Plutella xylostella (L.), in canola (Brassica napus L.)

Numbers of adult diamondback moth, Plutella xylostella (L.), captured in pheromone-baited traps may predict the density of damaging larval stages in canola, Brassica napus L. Two years of season-long experiments in Alberta, Canada compared captures of male moths in traps baited with commercial pheromone to larval densities. Significant relationships between moth catch and larval density were infrequent and generally curvilinear indicating that moth numbers were not directly related to larval density. Stronger relationships occurred late season and may indicate that population establishment is necessary before moth capture can predict larval populations. Relationships between moth capture and immature stages sampled at the same time were similar to those sampled two weeks later. A statistically similar number of moths was captured throughout the season in traps baited with lures changed at 6- versus 3-week intervals. During years of moderate and low populations of diamondback moth in canola, moth counts from one pheromone-baited trap per field are sensitive enough to detect densities of immature stages and are more accurate than sweep net sampling. Experiments have contributed to the development of a monitoring system to forecast P. xylostella densities in canola, but research of additional variables may help to develop a consistent relationship between moth catch and larval and pupal densities.     

Effects of pigment glands and gossypol on growth,development and insecticide-resistance of cotton bollworm (Heliothis armigera (Hübner))

Cotton bollworm (Heliothis armigera) is a major pest of cotton and other crops. It is important to understand the mechanisms of insecticide tolerance of cotton bollworm on cotton cultivars with host plant resistance to this insect pest. The objectives of this study were to investigate the effects of cotton pigment glands and their gossypol on the growth, development and insecticide tolerance of cotton bollworm. Three pairs of cotton isogenic lines with glanded versus glandless leaves, as well as artificial diets with 5 levels of gossypol, were used to raise cotton bollworm larvae for five generations. The growth, development and insecticide tolerance of larvae were studied. The results indicated that the cotton pigment glands and higher levels of gossypol resulted in a significant decrease in larval weights and moth eclosion rates and delayed the development of larvae and pupae. Larvae that fed on glanded cotton leaves were significantly more tolerant to two insecticides, cyhalothin and monocrotophos, than those fed on glandless cotton leaves. LD₅₀ values were only increased where they were in amount per unit body weight, and not where were calculated in amount per individual. Also the insecticide tolerance of cotton bollworm larvae increased as the gossypol content was raised from 0 to 0.225% in artificial diets. Meanwhile, the activities of two detoxifying enzymes, carboxylesterase and glutathione s-transferase, were significantly higher in the larvae fed on glanded cotton leaves than those fed on glandless cotton leaves. The activities of two enzymes also increased greatly with the increase of gossypol content from 0 to 0.225% in artificial diets. Across 5 generations of feeding and investigation, the significant inhibition effect on larval growth and larval tolerance to two pesticides were found to be only associated with the feeding by current generation, but were not related to previous diets. The activities of two detoxifying enzymes in larvae were also not enhanced significantly when they were fed continuously on glanded cotton leaves or artificial diet with high gossypol. These results indicated that pigment glands and higher levels of gossypol not only inhibited the growth of cotton bollworm larvae but also enhanced their insecticide tolerance. However, the inhibition effect and enhanced insecticide tolerance were inducible but could not be accumulated or inherited. These results will help us better understand the interaction and co-evolution of insecticide tolerance in larvae of cotton bollworm and host chemical components, and also has provided useful information on cotton bollworm management in cotton production, especially in glandless cotton.     

The Technical and Performance Characteristics of a Low-Cost,Simply Constructed,Black Light Moth Trap

The universal mercury vapor black light trap is an effective device used for collecting moth specimens in a wide variety of habitats; yet, they can present challenges for researchers. The mercury vapor trap is often powered by a heavy automotive battery making it difficult to conduct extensive surveys in remote regions. The mercury vapor trap also carries a considerable financial cost per trap unit, making trapping challenging with low research budgets. Here, we describe the development and trapping properties of a lighter, simply constructed, and less expensive trap. The LED funnel trap consists of a funnel, soda bottles with plastic vanes, and is powered by rechargeable 9-V batteries. Two strips of low-wavelength LEDs are used as attractants. We tested the trapping parameters of this trap design compared to a standard mercury vapor trap over 10 trap nights in a suburban woodlot in the summer of 2015. The mercury vapor trap caught significantly more moth individuals than the LED trap (average of 78 vs 40 moths per trap night; P < 0.05), and significantly more species than the LED trap (23 vs 15 per trap night; P < 0.05); the mercury vapor trap caught a total of 104 macromoth species over the duration of the study, compared to a total of 87 by the LED trap. Despite the lower yields, the low cost of the LED trap (<$30 ea.) makes it superior to the mercury vapor trap in cost-acquisition per moth species and per moth individual trapped. The LED trap may be a viable alternative to the standard mercury vapor trap, facilitating insect trapping in more diverse settings.     

Cotton-pest management in Egypt

Cotton (Gossypium barbadense L.) in Egypt is attacked by various pests and diseases during the different stages of its development. The cotton leafworm (Spodoptera littoralis (Boisduval)), the pink bollworm (Pectinophora gossypiella (Saunders)) and the American bollworm (Heliothis armigera (Hübner)) are the primary pests of cotton causing most damage. The system of cotton pest management adopted in Egypt is described in relation to the economic thresholds of infestation of various species. The management system includes cultural, mechanical and chemical control methods.     

Optimization of a monitoring system for the pine beauty moth, Panolis flammea (Denis & Schiffermüller), using sex attractants

The efficiency of traps baited with synthetic sex attractants, (Z)-9- and (Z)-11-tetradecenyl acetates, for Panolis flammea (Denis & Schiffermüller) (Lepidoptera: Noctuidae) was tested with respect to trap design, capacity, height, alignment, position and dose of lure. For optimum catches, traps should not be obstructed by vegetation, and can be placed most conveniently in forest rides. The most important features of trap design were a heavy surface coating of sticky retentive material and a large catching area. The efficiency of capture decreased rapidly when 40 or more moths were present on a sticky surface of area 380 cm². Numbers of moths caught increased regularly as the dose of lure increased from 1 μg to 5 mg. Males of Orthosia gothica (L.) (Lepidoptera: Noctuidae) were frequently caught in numbers similar to those of P. flammea in the same traps during the flight period of the latter insect. Increasing the relative quantity of the minor component, (Z)-11-tetradecenyl acetate, reduced catches of P. flammea, but not always those of O. gothica.     

Comparative toxicity of chlorfluazuron (IKI-7899) and cypermethrin to Spodoptera littoralis, Lobesia botrana and Drosophila melanogaster

Chlorfluazuron sprayed on cotton seedlings was more efficient than cypermethrin against third-instar larvae of the Egyptian cotton leafworm, Spodoptera littoralis. At a concentration of 3·2 x 10⁻⁵% a.i., chlorfluazuron caused 98 ± 2% larval mortality and cypermethrin 35 ± 9%. All larvae in chlorfluazuron assays died during moulting; hence the leaf area consumed during the test instar was not appreciably affected. On the other hand, in cypermethrin assays, larvae died during the intermoult stage. Chlorfluazuron exhibited potency similar to that of cypermethrin on third-instar larvae of the grape berry moth Lobesia botrana, resulting in 90–95% and 33–34% mortality in treatment concentrations of 5 x 10⁻³% and 2 x 10⁻⁴% a.i., respectively. In another grapevine pest, Drosophila melanogaster, cypermethrin suppressed larval and adult formation to a greater extent than chlorfluazuron. The high potency of chlorfluazuron on various insects, together with its low toxicity to man and the environment, renders this compound a potential agent for controlling important agricultural pests.     

Pheromone-mediated mating disruption in the millet stem borer, Coniesta ignefusalis (Lepidoptera: Pyralidae)

The millet stem borer, Coniesta ignefusalis Hampson (Lepidoptera: Pyralidae), is a major pest of pearl millet in the Sahelian region of Africa. The female sex pheromone has been identified and synthesised, and previous research had shown that the synthetic pheromone could cause high levels of reproductive communication disruption in small plots when released at rates of 640 mg/ha/day, using PVC resin formulation renewed every seven days to maintain efficiency. In the present research, in experiments in farmers’ fields in Niger, 86.8% (SE = 2.6%) communication disruption was achieved when polyethylene vials loaded with 0.5 mg pheromone at 400 dispensers/ha were used and replaced every 21 days. Polyethylene vials loaded with 80 mg pheromone gave uniform, zero-order release at approximately 0.05 mg/day at 27 °C. Experiments carried out on replicated 0.5 ha plots in farmers’ fields in Niger using a single application of these dispensers at 400 dispensers/ha resulted in at least 99% suppression of pheromone trap catches of male C. ignefusalis moths in treated plots relative to numbers in untreated plots for up to 3 months. However, sampling the central portions of these plots before and after harvest showed no significant differences in infestation, damage or yield loss between plots treated with pheromone and untreated plots. This may have been because of small plot size and the immigration of mated female moths into the treated plots which negated any reduction of mating of females within the treated plots. Comparisons of numbers of male C. ignefusalis moths in traps baited with the standard 0.5 mg monitoring lures and those baited with the 80 mg disruption dispensers showed catches in the latter were only 10-20% of those in the former; indicating high level communication disruptions in traps with high dose dispensers. Implications of using insect synthetic pheromones in the development of integrated management of C. ignefusalis in pearl millet cropping systems in the Sahel are discussed.     

Incidence and population fluctuation of Diuraphis noxia in Hungary

A yellow water pan trap was used to collect Diuraphis noxia (Mordvilko) in Central Hungary in 1989. In 1990 a Rothamsted-type suction trap collected 31 individuals. A D. noxia infestation was found in an autumn-sown wheat field in October 1990. The D. noxia population that overwintered was holocyclic. The life-span of fundatrices was 43.2 days at 18–22°C. The number of nymphs produced per fundatrix was 46.6. Average progeny numbers of first-generation apterae and alatae were 29.4 and 21.4, respectively. Second-generation apterae produced an average of 48.8 nymphs; 35.9% of nymphs were alatiform. The D. noxia population reached its peak on 3 July in the field, at which time the mean number of individuals per wheat plant was 3953.6. By 20 July, the wheat plants had matured and the D. noxia colonies had disappeared from the wheat.     

Manual topping decreases bollworm infestations in cotton cultivation in Mali

In sub-Saharan areas of Africa, cotton growers no longer cut the shoot tips from plants (topping), although manual topping was promoted at the start of the 20th century to improve yield and, surprisingly, to reduce pest incidence. In these areas, the bollworms Helicoverpa armigera Hübner, Earias spp., and Diparopsis watersi Rothschild are responsible for the majority of cotton yield losses, and the use of pyrethroids has resulted in resistance in field populations of H. armigera. In the face of these problems and given the scarcity of literature on the effects of topping on pest control, we assessed bollworm infestation levels in 12 trials comparing manual topping and non-topping cotton plots in Mali over a six-year period (2002, 2003, and 2005 to 2008). Topping was performed at the emergence of the 15th sympodial branch or at 10 days after the first flower opening. Our results showed no significant difference in seed cotton yields between topped and non-topped cotton. Bollworm infestations (all species) were always lower on topped cotton and 7 out of 12 trials showed significantly lower infestations on topped cotton. In plots of topped cotton, we recorded an average of 56% fewer H. armigera larvae, 68% fewer Earias spp. larvae, and 71% fewer D. watersi larvae with respectively 5, 4, and 3 out of 12 trials with significant differences in favor of topping and no significant difference in favor of non-topping. To our knowledge, our study is the first to report decreases in D. watersi larval infestation with cotton topping. Further studies are required to understand the mechanisms involved in these effects and to ensure that topping is economically attractive for farmers.     

Cereal leaf beetle (Oulema melanopus (L.)) population densities and winter wheat yields

Grain yields of a soft white winter wheat cultivar, cv. Ionia, susceptible to cereal leaf beetle (Oulema melanopus (L.)), were determined when the crop was subjected to four controlled infestation levels of the beetle in caged plots over a 3-year period in Michigan. Although identical infestation procedures and insect numbers were used each year, the intensity of larval infestation and feeding damage varied with the year. Significant (P < 0·01) grain losses occurred in plots that had at least 9·0 larvae per stem. The greatest yield loss was 45% and occurred with 15 larvae per stem and 85% feeding damage. Beetle damage had a greater effect on kernel weight than on the other yield components. Although economic thresholds should be conservative to allow for environmental variations, it appears that soft white winter wheat can often withstand beetle infestation levels greater than the current economic threshold of three or more eggs and largae per stem before the boot stage or one or more large larvae per flag leaf during heading.     

Disruption of Darna pallivitta (Lepidoptera: Limacodidae) by Conventional and Mobile Pheromone Deployment

Identification of the Darna pallivitta (Moore) pheromone component n-butyl (E)-7,9-decadienoate (E7,9-10:COOn-Bu) has made it possible to investigate communication disruption to control this lepidopteran pest. Conventional communication disruption trials showed marked decreases in the mean number of male moths captured in E7,9-10:COOnBu-treated fields compared with control fields. For traps baited with E7,9-10:COOnBu, percent disruptions were 94.4% and 92.1% for septa (1 g pheromone/ha, 1-wk trial duration) and spirals (6 g pheromone/ha, 8-wk trial duration) respectively. For traps baited with virgin female moths, percent disruption was 73.3% using septa disruptors (1 g pheromone/ha, 1-wk trial duration). Mobile communication disruption using Bactrocera cucurbitae (Coquillett) as carriers for E7,9-10:COOn-Bu was evaluated in the following three areas: fly survivorship, attraction of male moths to treated flies, and moth disruption in a small-scale field trial. Topical application of E7,9-10:COOnBu showed no significant decrease in survivorship at 50 and 80 µg/fly. However, decreased survivorship was observed at 100 µg/fly and linear regression showed E7,9-10:COOnBu dose was significantly correlated with B. cucurbitae survivorship. Traps containing honey–pheromone-fed flies attracted and caught D. pallivitta over a 1-wk period, demonstrating the attractiveness of the carrier. Releasing E7,9-10:COOnBu-fed B. cucurbitae (∼2 g pheromone/ha, 1-wk trial duration) resulted in significantly reduced trap catches in treatment fields compared with control fields on the first 2 d of the field trial. Percent disruptions were 84.7% (day 1) and 56.0% (day 2). These results suggest that both conventional communication disruption and mobile communication disruption have potential to control D. pallivitta.     

水稻二化螟性信息素技术：粘胶诱捕器、性诱剂保存期和剂量

对不同剂量、不同保存期的性诱剂和几种常见诱捕器进行了田间诱蛾效果比较研究。结果表明,诱芯所含的性诱剂的剂量以300 μg为宜;在低温条件下保存1年对其诱蛾效果影响不大;泥盆诱捕器的诱蛾效果不理想,粘胶诱捕器的诱蛾效果也不及水盆诱捕器,但操作较为方便;在田间设置时,其适宜高度需随水稻高度而变化。     

昆虫性信息素配备新型飞蛾诱捕器群集诱杀水稻二化螟的效果研究

对新型飞蛾干式诱捕器诱捕效率进行了测试,从6月20日至9月20日,共调查13次,累计诱蛾量8 605头,平均每台诱捕器诱蛾344头。性诱剂处理区、施药区和不施药区虫伤株率分别为为1.77%、1.19%和81.90%,枯鞘率分别为1.11%、0.65%和14.68%,白穗率分别为1.87%、0.35%和38.83%。性诱剂防治效果95.18%,比药剂防效低3.92个百分点。就本试验结果来看,新型诱捕器操作简便,易于维护,使性信息素大面积诱杀二化螟的可行性提高。     

Monitoring and action threshold determination for the obscure mealybug Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) using pheromone-baited traps

The absence of effective pest monitoring has resulted in an increase in populations of the obscure mealybug Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae) in pome fruit orchards in the Western Cape Province of South Africa recently. The sex pheromone for P. viburni was recently identified and synthesized. Flight activity of adult male P. viburni was monitored by placing and servicing three, evenly spaced pheromone-baited traps per orchard in three pome fruit growing regions used for the study. Fortnightly fruit sampling was done by randomly picking three fruits per tree for the duration of each fruit season, dissecting and noting mealybug infestation. The biweekly male P. viburni trap catch information and fruit infestation data collected over two seasons were correlated. There was a positive and significant relationship between the fruit infestation and number of P. viburni adult males caught in pheromone-baited traps (r² = 0.454, P < 0.001). The action threshold level was estimated to be 2.5 male P. viburni caught per trap per fortnight at an economic threshold of 2% fruit infestation. This monitoring method was less labor intensive, more accurate and quicker than the current visual sampling and monitoring techniques.     

Efficacy and stability of sex-attractant lures for Cydia nigricana (F.) and Cydia medicaginis (Kuzn.)

Field experiments are described in which sex-attractant lures for male pea moth, Cydia nigricana (F.), were compared in the UK and France, to explain earlier anomalies between results in the two countries. These were caused by differences in formulation, rather than in trap design or crop; there was no evidence for the existence of different biological races. Freshly exposed lures containing (E,E)-8,10-dodecadien-1-yl acetate (E,E8,10–12:Ac) from France (INRA) or the UK (Rothamsted) attracted similar numbers of moths in both countries, but the INRA lures rapidly became less attractive because they did not contain antioxidant to prevent the formation of a product repellent to male moths. The experiments in France also confirmed that E,E8,10–12:Ac is a more powerful attractant than (E)-10-dodecen-1-yl acetate for the pea moth, in agreement with previous results in the UK. Similar experiments, only in France, with the lucerne moth, Cydia medicaginis (Kuzn.), confirmed that E,E8,10–12:Ac is a powerful attractant, and showed that field-exposed E,E8,10–12:Ac is repellent to this species also.     

Optimum density of chrysanthemum flower model traps to reduce infestations of Frankliniella intonsa (Thysanoptera: Thripidae) on greenhouse strawberry

In a previous study, we showed that a chrysanthemum flower model trap, developed by modifying an artificial yellow chrysanthemum flower, was more attractive to the flower thrips Frankliniella intonsa Trybom (Thysanoptera: Thripidae) than a commercial yellow sticky trap. In this study, the optimum deployment density of the chrysanthemum flower model trap for reducing thrips infestation was investigated in commercial strawberry greenhouses. The traps were installed within the plant canopy at different densities (0, 5, 10, 20 traps per 50 m² plot) in three greenhouses using a randomized complete block design. The highest density of traps reduced seasonal populations of F. intonsa on strawberry flowers by 82% compared to the untreated control. The traps caught approximately 4.6 times more female than male F. intonsa, though the numbers of females and males in the flowers were similar and were both equally reduced with increasing trap density. A weak correlation (r = 0.54) was found between the number of female F. intonsa trapped and numbers in strawberry flowers, but there was no correlation (r = −0.03) for males. The results indicate flower model trap can be an additional tool for monitoring and/or management tactics against this anthophilous thrips.     

Mechanically-applied wax matrix (SPLAT-GBM) for mating disruption of grape berry moth (Lepidoptera: Tortricidae)

An ATV-mounted mechanical applicator was designed to treat vineyards with SPLAT-GBM™ for mating disruption of grape berry moth, Paralobesia viteana (Lepidoptera: Tortricidae). SPLAT-GBM was applied to vineyards in 0.8 g drops at a density of 1544 or 3089 drops per hectare for a total of 1.3 or 2.5 kg per hectare. Trials were conducted in 2008 and 2009 in vineyards receiving grower-standard insecticide sprays for control of grape berry moth and other insect pests. In the first trial, SPLAT-GBM applied twice at 1.3 or 2.5 kg/ha caused a significant reduction in grape berry moth infestation at harvest on clusters at the border of the vineyards where infestation is highest, compared with the no-pheromone control, but three applications at 2.5 kg/ha did not result in lower infestation compared with both the control and other treatments. In the second trial, application of SPLAT-GBM 2.5 kg/ha in mid-June and late-July caused a significant reduction in grape berry moth infestation at harvest on clusters at the border of the vineyards. Application in early-May and late-June resulted in infestation that was similar to the other program, but not statistically different from the control. In both trials, there were no significant differences between any of the treatments of SPLAT-GBM and the control inside the vineyards where infestation is low. Among treatments of SPLAT-GBM, infestation was similar regardless of number, rate, or timing of the applications. This study shows that mechanical application of wax matrix drops to release pheromone is an effective method for control of grape berry moth using mating disruption.     

Pre-harvest survival of codling moth in artificially infested sweet cherry fruits

Prior to the 2009 season, sweet cherry fruits, Prunus avium (L.) L., from North America were required to be fumigated with methyl bromide before being exported to Japan to eliminate possible infestation by codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). However, based on recent biological research on host status, a new procedure (the “systems approach”) was implemented relying on the cumulative effects of pre- and post-harvest practices to produce pest-free sweet cherry fruits for export. This is an organized process that involves the integration of procedures used in the production, harvest, packaging, and distribution of a commodity which cumulatively meet the requirements for quarantine security. The objective of our study was to provide additional information to support the systems approach for codling moth in sweet cherries fruits. For four seasons, branches with sweet cherry fruits were caged on trees and infested by released ovipositing codling moths into the cages. Fruits were sampled weekly for codling moth individuals at each life stage. Eggs were laid mostly on leaves with the seasonal average numbers per cage ranging from 142 to 617. Populations declined rapidly after egg eclosion, with <1.5% of the original cohort surviving to fifth instars. Even after 8 weeks, none had formed cocoons or pupated. This failure of the codling moth to complete a life cycle under field conditions supports previous life history studies and demonstrates that sweet cherry fruits are inadequate hosts for codling moth.     

鸡脚叶对陆地棉光合特性的影响

用远缘杂交后代为材料,测定了不同叶型不同时期的叶绿素含量、光合强度.结果表明:在吐絮期前鸡脚叶叶片的叶绿素含量和光合作用强度均高于正常叶.而在吐絮期后正好相反.考查了不同叶型的单株结铃数、铃重、衣分、虫籽率和僵瓣率.试验结果表明:鸡脚叶对陆地棉产量没有不利影响;与正常叶比较,红铃虫为害的虫籽率和僵瓣率分别低32.7%和18.8%.