Semiochemical and natural product-based approaches to control Spodoptera spp. (Lepidoptera: Noctuidae)

The genus Spodoptera contains some of the most destructive crop pests in the world owing to the worldwide distribution of the different species and their wide host ranges. Uses of semiochemicals for insect control have been recently reviewed, but strategies developed specifically against Spodoptera species are scarce. In this review, we present an updated account of the semiochemicals and other natural product-based approaches to monitor and control the most damaging Spodoptera spp. In general, successful control of Spodoptera littoralis, S. frugiperda, S. litura, and S. exigua have been reported through mass trapping, mating disruption, and attract-and-kill methods. An updated survey of the pheromone components of these species and an outlook of future perspectives against these pests are also outlined.     

Infectivity prospects of both nematodes and bacterial symbionts against cotton leafworm, Spodoptera littoralis (Biosduval) (Lepidoptera: Noctuidae)

A study was made on the susceptibility of the cotton leafworm, Spodoptera littoralis (Biosd.), to the nematode, Steinernema carpocapsae (All) and Heterorhabditis bacteriophora. Three concentrations of each nematode species were used (75, 150, and 300 infective juveniles) for each treatment. The nematode, H. bacteriophora, gave 100% mortality 96, 90, and 48 h, respectively, post-treatment of S. littoralis larvae with 75, 150, and 300 infective juveniles. On the other hand, S. carpocapsae (All) gave 100% mortality 120, 90, and 56 h post-treatment, respectively. Therefore, H. bacteriophora was more potent against cotton leafworm than S. carpocapsae. Studies on the infestation intensity of the nematode species against the cotton leafworm showed the predominance of H. bacteriophora over S. carpocapsae, while in studies of the reproductive rate those of S. carpocapsae predominate. The bacterial symbionts of each nematode species were isolated and tested alone against cotton leafworm at concentrations ranging between 1×10² and 5×10³ bacterial cells/larva. The results showed a higher activity of Photorhabdus luminescens than that of Xenorhabdu nematophilus.     

Field resistance of Spodoptera litura (Lepidoptera: Noctuidae) to organophosphates, pyrethroids, carbamates and four newer chemistry insecticides in Hunan, China

The present studies were carried out to evaluate resistance in the populations of Spodoptera litura Fab. (Lepidoptera, Noctuidae) from five districts of Hunan Province in China to various insecticides from 2010 to 2012 using a standard leaf dip bioassay method. For organophosphates and pyrethroids, resistance ratios compared with a susceptible Lab-BJ strain were in the range of 14–229-fold for organophosphates and 12–227-fold for pyrethroids. Similarly, relative low levels of resistance to emamectin, indoxacarb, and chlorfenapyr were observed in all five populations. In contrast, the resistance to carbamates (thiodicarb or methomyl) was significantly higher than that of organophosphates, pyrethroids and newer chemistry insecticides. The pairwise correlation coefficients of LC₅₀ values indicated that the newer chemistry insecticides and old generation insecticides were not significant except abamectin, which was negatively significantly correlated with methomyl. A significant correlation was observed between thiodicarb, methomyl, and deltamethrin, whereas resistance to bifenthrin showed no correlations with resistance to other insecticides except deltamethrin. The results are discussed in relation to integrated pest management for S. litura with special reference to management of field evolved resistance to insecticides.     

Field evolved resistance to carbamates,organophosphates, pyrethroids,and new chemistry insecticides in <Emphasis Type="Italic">Spodoptera litura</Emphasis> Fab. (Lepidoptera: Noctuidae)

Spodoptera litura Fab. (Lepidoptera, Noctuidae) is a polyphagous pest and has been shown to be resistant to a wide range of insecticides, which has led to sporadic out breaks of the pest and failure of crops. We were interested to establish if resistance to insecticides is diverse in different populations of S. litura collected from various areas with variable temperatures. We collected S. litura from eight different locations and compare the toxicity of insecticides. Resistance to the pyrethroids ranged from 20- to 11,700-fold compared with the Lab-PK (laboratory susceptible population). The resistance to bifenthrin was the lowest in a population collected from Multan and the highest to esfenvalerate in a population collected from Lodhran. Similarly, very high level of resistance to spinosad, indoxacarb, and methoxyfenozide was observed in all eight populations. In contrast, resistance to organophosphates was significantly lower than the pyrethroids, spinosad, indoxacarb, and methoxyfenozide, while toxicity of emamectin to field populations was similar to the Lab-Pk. The results are discussed in relation to integrated pest management (IPM) for S. litura with special reference to management of field evolved resistance to insecticides.     

Herbivory affects ovarian development in the zoophytophagous predator <Emphasis Type="Italic">Brontocoris tabidus</Emphasis> (Heteroptera,Pentatomidae)

The effect of prey-based and combination prey and plant-based diets [Tenebrio molitor pupae alone; T. molitor pupae and Eucalyptus cloeziana plants; T. molitor pupae and Eucalyptus urophylla plants; and T. molitor pupae and Psidium guajava (guava) plants] on the morphometry of the ovary of Brontocoris tabidus (Signoret) (Heteroptera: Pentatomidae) was analyzed in the field. Females fed on T. molitor pupae without plants presented with smaller ovarioles. The number of oocytes per ovary was higher for B. tabidus females fed on a combination diet of E. urophylla and T. molitor pupae when compared to females fed only on prey. In addition to diet, the number of oocytes in the ovariole was shown to vary with the age of B. tabidus. The 21-day-old B. tabidus females were found to have a higher number of oocytes per ovariole than the 15-day-old females in all diet conditions. The 15-day-old females exhibited more developed oocytes when fed on diets containing both prey and eucalypts plants and less developed oocytes when fed with a combination diet containing guava plants or T. molitor pupae alone. The 21-one-day-old B. tabidus females which were fed with a diet without plants had smaller oocytes than those fed with plants. Herbivory improves the morphology of the ovary of B. tabidus, affecting the size of the reproductive structures and the oogenesis of this natural enemy in the field.     

Survey of the parasitoids of the Greasy Cutworm,Agrotis ipsilon Rott. (Lepidoptera,Noctuidae) in Egypt

Weekly samples of the cutworm,Agrotis ipsilon Rott. larvae were collected for 3 successive season 1983/84–1985/86 from 3 Governorates in middle Egypt to survey and evaluate the role of parasitoids in suppressing the pest population.Two gregarious internal larval parasitoids were recorded,Apanteles ruficrus Hal. andMeteorus rubens Nees. (Hymenoptera, Braconidae). Percentages of parasitism were estimated. They reached 20.2, 22.2 and 24.7% in seasons 1983/84, 1984/85 and 1985/86, respectively, with an average of 22.5% (10.3%A. ruficrus and 12.2%M. rubens). The highest rates of parasitism were recorded in March and April.

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Zusammenfassung Wöchentliche Aufsammlungen der Raupen vonA. ipsilon während der Jahre 1983/84 bis 1985/86 im mittleren Ägypten erbrachten zwei gregäre Endoparasitoiden,Apanteles ruficrus Hal. undMeteorus rubens Nees. (beide Hym., Braconidae). Sie erreichen zusammen in den 3 Jahren 20,2, 22,2 und 24,7%, i.M. 22,5% (A. ruficrus=10,3%, undM. rubens=12,2%). Die höchsten Parasitierungsraten wurden im März und April festgestellt.

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Activity ofBacillus thuringiensis Berl. on the lesser cotton leafwormSpodoptera exigua Hbn. (Lep., Noctuidae) in corn and sunflower cultivations in Egypt

Field applications usingBacillus thuringiensis (Dipel 2 X) againstSpodoptera exigua infesting corn and sunflower cultivations were carried out in two different localities in Egypt. The percentage of infested corn plants decreased to 2.5%, seven days after treatment with Dipel 2x, (250 g/fed) and the yield was significantly increased compared with untreated plots. The carbamate insecticide (Lannate) at 300 g/fed caused complete kill to the larvae and the highest yield was obtained. Application of Lannate, Dipel (250 g) or a combination of both (150 g/each/fed) caused a high reduction of the larvae existing in sunflower after seven days from application, while Dipel at 200 g/fed gave a lower effect. Ten days after application, the number of larvae and infested plants increased significantly in plots treated with Lannate alone, while plots treated with either Dipel (250 g) or Dipel combined with Lannate (150 g/each) still maintained a lower infestation. The estimated yield showed the highest increase in plots treated with Lannate followed by Dipel (250 g) and then a combination of both.     

Characterization of antibiosis to the redbanded stink bug Piezodorus guildinii (Hemiptera: Pentatomidae) in soybean entries

Stink bugs are among the major pests of soybean [Glycine max (L.) Merrill] worldwide. Piezodorus guildinii [Westwood] (Hemiptera: Pentatomidae) is one of the predominant pest species, causing more severe damage in many regions than other stink bugs. Its attack reduces yield and quality of the beans. Plant resistance is a valuable strategy in integrated pest management that can reduce insect populations below economic injury level. Here, we report the resistance of 17 soybean entries to P. guildinii. PI 229358, PI 274454, L1-1-01, “IAC 19,” PI 171451, PI 227687, “IAC 100,” IAC 78-2318, PI 274453, and IAC 74-2832 caused high nymphal mortality (greater than 90 %), indicating the expression of antibiosis. “IAC 100,” IAC 74-2832, PI 274453, and “IAC 24” also increased the length of the nymphal stage of P. guildinii, showing the same mechanism of resistance. Our findings may be useful for breeding programs that focus on the resistance of soybeans to insects.     

Development of Thaumetopoea pityocampa schiff. (Lepidoptera: Thaumetopoeidae) in relation to food consumption

T. pityocampa is the most harmful needle-eating insect of the Greek pine forests. Field trials in the Thessaloniki area of N. Greece showed that the development of young larvae which were enclosed in cloth bags on trees of the experimental site was greatly influenced by the kind of food the larvae consumed. Food consisted of needles from five pine species: Pinus brutia Ten., P. pinea L., P. maritima Lam., P. halepensis Mill., and P. radiata D. Don. Larvae had greatest weight gain and rate of development when fed on leaves of P. radiata, and least when fed on those of P. pinea.     

Effects of different neem preparations in comparison to synthetic insecticides on the whitefly parasitoid Encarsia sophia (Hymenoptera: Aphelinidae) and the predator Chrysoperla carnea (Neuroptera: Chrysopidae) on cotton under laboratory conditions

The contact and feeding toxicity of NeemAzal T/S (EID Parry, Chennai, India) to the parasitoid Encarsia sophia (Girault & Dodd) was compared with three synthetic insecticides (chlorpyriphos, endosulfan and triazophos) against immatures and adult emergence. NeemAzal T/S (1.0%) at lower dose (200 mg/l) did not cause any effect on the emergence of E. sophia adults, but there was a significant reduction in emergence at higher doses (800 mg/l). Also, it did not show contact toxicity to adults of E. sophia, but there was a significantly high feeding mortality in a dosage dependant manner, whereas chlorpyriphos, endosulfan and triazophos showed high toxicity both by contact and feeding method. Three neem preparations registered in India, NeemAzal T/S, Nimbecidine (T. Stains, Coimbatore) and Godrej Achook (Godrej Agrovet, Mumbai) were tested against egg and larval stages of Chrysoperla carnea (Stephens) at three dosages, using a synthetic insecticide, triazophos 40 EC (200 mg/l), for comparison under laboratory conditions. The three biorationals did not induce any adverse effect on the hatchability of C. carnea eggs. The mortality of the first instars of C. carnea was not affected by any of the azadirachtin enriched formulations; however, at higher dosage of 800 mg/l these neem based products resulted in increased mortality of the first and second instar larvae of C. carnea relative to the untreated controls. Whereas, triazophos induced very high mortality rates (85.0, 89.0 and 81.5%) of all the three larval instars. The neem based insecticides showed a dosage-dependant effect on the larval instars of C. carnea. Thus, these biorationals show that there is a potential to use them in an IPM system, being safe for natural enemies of B. tabaci in cotton.     

Evaluation of management tools for the control of poplar leaf defoliators (Lepidoptera: notodontidae) in northwestern India

Populus suffers from multiple insect damage throughout its distributional range in northwestern India. The evaluation of various management tools was done based on the hypothesis that manipulation of insect habitat can provide tangible results. Manipulation of cultural practices, ploughing of field during December, and growing of crops (wheat, Trifolium alexandrinum and others) results in lower adult emergence, reduced leaf infestation, number of larvae and pupae per meter branch length of poplar leaf defoliators (PLD). Fallow plantations were more prone to attack of PLD than intercropped plantations. Higher incidence of Clostera restitura was recorded in southwestern dry zones due to unsuitability of the site, poor quality of irrigation water and dry weather conditions. Complete stripping of Populus trees does not occur in low temperature & high humidity, submountaneous zones of Punjab. Chemical control studies were conducted in laboratory & field conditions, and among the five insecticides tested, Profenophos 50 EC, Quinalphos 25 EC and Carbaryl 50 WP @ 0.05 and 0.1 percent concentration gave consistently high mortality of PLD larvae up to 21 days after spraying. Use of insecticides prior to peak activity periods & during evening hours enhances the efficiency of management options.     

Attack and defense movements involved in the interaction of <Emphasis Type="Italic">Spodoptera frugiperda</Emphasis> and <Emphasis Type="Italic">Helicoverpa zea</Emphasis> (Lepidoptera: Noctuidae)

The fall armyworm, Spodoptera frugiperda (J. E. Smith) and the corn earworm, Helicoverpa zea (Boddie) are among the main pests of maize. Both species exhibit cannibalistic behavior and quite often share the same feeding guild in maize (maize ears), which can result in several interspecific and intraspecific interactions. Paired interaction scenarios of intraspecific and interspecific larvae were assessed in arenas in the presence and absence of food to characterize movements resulting from interactions of these insects. There was a difference in the frequency of behavioral movements in all the interactions, except for S. frugiperda in the presence of food. Head touching and recoiling were the predominant movements in most of the interaction scenarios. Spodoptera frugiperda exhibited a predominance of defensive movements when competing against H. zea in the same instars. Cannibalism and predation occurred frequently in interactions involving 6th instar of H. zea against opponents in 4th instar. Larvae of H. zea show a higher aggressive movement than S. frugiperda. The larvae of S. frugiperda take advantage during the interactions, although they present more defensive movements compared to H. zea. This study provides relevant information regarding the interaction of these species and intraguild interaction, which might influence the population dynamics and the competitive displacement of pest species that share the same ecological niche.     

Egg detection in females of the polyphagous predator <Emphasis Type="Italic">Macrolophus pygmaeus</Emphasis> (Heteroptera: Miridae) by serological techniques

Macrolophus pygmaeus is a polyphagous mirid bug native to the Mediterranean area where it is widely used in the biological control of whiteflies and other pests in vegetable crops. To assess the presence of eggs in females is important in order to optimize predator release strategies, as well as their mass rearing. This study shows an alternative to the traditional procedures of fertility assessment based on evaluation of newly hatched nymphs. A polyclonal antiserum was produced against M. pygmaeus egg proteins, and an ELISA protocol was developed to determine whether laboratory-reared or field-collected females contained egg proteins (mainly vitellin). When field-collected females were analysed, an 80% contained egg proteins indicating that they were reproductively active. Presence/absence of egg proteins was detected with an error than 1%. Since this ELISA protocol allowed also the detection of egg protein precursors, it was more precise and less time consuming than conventional techniques as abdomen dissection or egg-hatch evaluation in determining egg presence in females.     

Utilization of diflubenzuron to controlgelechia senticetella (Stgr.) (Lepidoptera: Geiechiidae), a dangerous pest ofjuniperus excelsa M. B. (Cupressaceae) in Bulgaria

In 1992, experiments were carried out in Bulgaria to controlGelechia senticetella (Stgr.) (Lepidoptera: Geiechiidae), a mining pest on the needles and young shoots ofJuniperus excelsa M. B. by commercial products Dimilin ODC-45 and Dimilin WP-25 based on the insect growth regulator diflubenzuron. Two Ultra Low Volume (ULV) treatments were performed - on March 12^th and April 16^th, during the emerging of the pest larvae out of the infested shoots. Dimilin ODC-45 was applied in a dose of 60-120 ml/ha (27-54 g a.i./ha), dissolved in 5l of diesel oil, and Dimilin WP-25 - in a dose of 200 g/ha (50 g a.i./ha) dissolved in 5l of water. The effect of Dimilin ODC-45 was very high - 92.5-97.6 %. The effect of Dimilin WP-25 was unsatisfactory - 63.4-70.0 %, which was most probably due to the fact that the oil emulsions adhere to the treated plants better than the water solutions, thus ensuring a longer period of action.     

Mating disruption of the pink bollworm<Emphasis Type="Italic"> Pectinophora gossypiella</Emphasis> (Saund.) (Lepidoptera: Gelechiidae) using gossyplure PB-rope dispensers in cotton fields

The effects of mating disruption on population densities and percentage of damage of the pink bollworm Pectinophora gossypiella (Saunders) were investigated in a cotton field in central Greece, in 1992 and 1993. A 10-ha field was divided in two parts of 5 ha each. PB-rope dispensers were installed in mid-season in one part, whereas the other was used as a control field. Catches of pink bollworm moths in pheromone-baited traps and damage caused were recorded in both the treated and control fields. Results showed that moth catches were highly reduced in the treated field and, therefore, mid-season installation of dispensers was successful. Damage (%) was significantly less in the treated compared with the control field. Consequently, the field size of 5 ha seems to be adequate for the effective implementation of mating disruption.     

Dynamics of resistance to organophosphate and carbamate insecticides in the cotton whitefly <Emphasis Type="Italic">Bemisia tabaci</Emphasis> (Hemiptera: Aleyrodidae) from Pakistan

Field populations of adult whiteflies, Bemisia tabaci, from Pakistan were monitored from 1992 to 2007 for their susceptibility to seven organophosphate and three carbamate insecticides using a leaf-dip method. Malathion, quinalphos and chlorpyrifos generally exhibited no or a very low level of resistance in B. tabaci over a 16-year monitoring period. Resistance to profenofos, triazophos, parathion-methyl and ethion was usually low to high up to 1995, and then it dropped to very low levels during 1996–2004. Resistance levels again picked up from low to moderate levels for triazophos during 2005–2007, for parathion-methyl during 2003–2007, and for ethion in 2006. Among carbamates, thiodicarb resistance was high during 1994–1996, which dropped to moderate levels in 1997 and 1998 and to very low levels during 1999–2001, but again increased from low to high levels during 2002–2007. Methomyl resistance was moderate in 1994 and 1995, which dropped to very low levels during 1996–2002, and then increased to low levels during 2003–2007. Butocarboxim resistance remained very low during 1994–2003 and then increased from low to high levels during 2004–2007. The insecticides exhibiting no, very low or low resistance, and no cross-resistance among themselves can be exploited in devising an insecticide resistance management strategy to combat whitefly resistance in the field.     

Neem-based integrated approaches for the management of tea mosquito bug, <Emphasis Type="Italic">Helopeltis theivora</Emphasis> Waterhouse (Miridae: Heteroptera) in tea

Despite continuous use of synthetic insecticides during last two decades, the tea mosquito bug, Helopeltis theivora Waterhouse (Miridae: Heteroptera), has become the most destructive sucking pest of tea in North East India. In order to reduce the load of the synthetic chemicals in tea vis-à-vis their deleterious effect, integration of biopesticide, synthetic pesticides along with effective spraying strategies, have been attempted. The anti-insect property of “neem”, Azadirachta indica A. Juss. (Meliaceae), has been used to solve many pest problems. In this study, different azadirachtin concentrations were evaluated at different doses against the H. theivora to find out their controlling efficacy. At 50,000 ppm azadirachtin concentration 65% control of infestation could be attained, whereas at 3,000 and 10,000 ppm, gave 30–43% reduction and 300 and 1,500 ppm <30% control was possible. Further in case of 3,000 and 10,000 ppm, azadirachtin concentration 30–43% reduction was registered. Therefore, azadirachtin concentration and its dilutions are the major criteria for getting desired bioactivity. Treatments with combined formulations viz. “neem + endosulfan” or “neem + deltamethrin” recorded significant reduction in H. theivora incidence even at reduced doses, as compared to sole application of neem or synthetic insecticide at recommended doses. Effective combinations and dose of the insecticides along with their formulations in controlling H. theivora have been presented and discussed.     

Relative susceptibility of four species of African mahogany to the shoot borer Hypsipyla robusta (Lepidoptera: Pyralidae) in the moist semideciduous forest of Ghana

We examined the relative susceptibility of four mahogany species, Khaya ivorensis, Khaya anthotheca, Entandrophragma angolense, and E. utile, to Hypsipyla robusta attack. Seeds were obtained from one to three parent trees for each species. The research was conducted in the moist semideciduous forest zone in Ghana and used a randomized complete block design. Tree height and diameter and height to first branch were measured until 24 months after out-planting in the field. H. robusta damage was assessed by counting the numbers of shoots attacked, branches, and dead shoots. Khaya spp. grew better but experienced more attack than Entandrophragma spp. The relative susceptibility to H. robusta attack, from most to least, of the four species was: K. anthotheca > K. ivorensis > E. angolense > E. utile. At 24 months, the mean number of shoots attacked per tree ranged from 1.0 for an E. utile seed source to 3.6 on for a K. anthotheca seed source. At 15 months, K. anthotheca and K. ivorensis started branching at about 1.5 m, but height of clear trunk increased over time due to self-pruning. As K. anthotheca grew taller, the number of H. robusta attacks per tree declined. This suggested that selection of genotypes and species that are tolerant of H. robusta attack based on infestation of young plants may not be appropriate. Genetic factors more completely reflecting the response of different species and genotypes to H. robusta attack may manifest themselves at later growth stages.