Biology and behaviour of Ephestiasula pictipes (Wood-Mason) (Hymenopodidae: Mantodea) under captive breeding

The biology and behaviour of a common predator in cashew plantations, Ephestiasula pictipes (Wood-Mason), were studied under captivity for three seasons using greater wax moth larvae as prey. During Feb–May, incubation and nymphal developmental period were shorter when compared with Jun–Sep and Oct–Jan. The female mantids laid ootheca once in every 3–4 days, for a period of 70–77 days. Adult longevity and oviposition period were significantly higher during Feb–May, while no significant difference was observed in sex ratio, oviposition interval and pre oviposition period during different seasons. Sexual behaviour consisted of preliminary courtship and copulation, involving 14 activities in sequence. Duration of mounting, copulation and riding around on the female by the male widely varied from 2 min to 28 h; 5.15 to 6.10 h; and 2 to 74 h, respectively. High fertility, high fecundity, shorter life cycle, multivoltinism and feasibility of laboratory rearing throughout the year are the advantageous features of E. pictipes that permits for its mass rearing and emergence as a viable biocontrol agent in future.     

云南扁萤的生活史及行为学研究

云南扁萤在四川乐山地区2～4月孵化,10月下旬雄虫羽化,11月上旬雌虫羽化,成虫寿命约25～45 d,产卵高峰出现在每年的11月中、下旬,以卵越冬,卵期约60d,一个世代需要1～2年.云南扁萤雌性成虫具有抱卵行为,能有效保护卵:幼虫以反应性出血和假死行为共同组成了其防御体系.     

Effect of surface material on electrostatic charging of houseflies (Musca domestica L)

Houseflies (Musca domestica L) accumulated electrostatic charges when walking over clean, uncharged dielectric surfaces. The charges elicited on a walking housefly by a range of materials were quantified, allowing a triboelectric series to be determined relative to M domestica. This ranged from surfaces that charged individuals positively, e.g. Correx (corrugated polypropylene) [.1 (+/- 4.2)pC], to those that applied a negative charge, e.g. clear cast acrylic [-14.9 (+/- 2.9)pC]. Maximum positive and negative charges accumulated by individual M domestica were +73 and -27 pC. Replicate measurements on the same fly and surface showed little variation. Variation between individuals was not related to sex and was not consistent between surfaces. Different materials charged M domestica significantly differently and individual flies had significantly different charging properties. Variation in temperature between 21.3 degrees C and 24.7 degrees C and humidity between 24% and 41% RH significantly affected charge accumulated by M domestica on some surfaces, although further experimentation is needed to confirm this. The implications of this work are discussed in relation to insect trap design and pollination biology.     

Behavioural response of Colorado potato beetle (Leptinotarsa decemlineata) larvae to selected plant extracts

Potato leaves were treated with 2, 20 or 200 g kg(-1) solutions of extracts of five plant species collected in Turkey, and then exposed to larvae of Colorado potato beetle, Leptinotarsa decemlineata (Say). During the first 24 h of exposure, leaf consumption was not affected by 2 g kg(-1) extracts, whereas significantly more leaf tissue remained on leaves treated with 20 g kg(-1) extracts of Arctium lappa L., Bifora radians M Bieb, Humulus lupulus L. or Xanthium strumarium L. than on untreated control leaves. Feeding was not affected by the 20 g kg(-1) extract of Verbascum songaricum Schrenk ex Fisch & Mey. Extracts of all species at 200 g kg(-1) reduced larval feeding, with H. lupulus and X. strumarium providing the greatest protection. Observations of larval behaviour over the first 15 min of exposure to these extracts revealed that the interaction of beetles with leaf tissue was significantly affected by plant extracts. Feeding frequency was not affected by 2 g kg(-1) extracts but was reduced by all higher concentrations. Feeding was inhibited completely by 20 g kg(-1) of H. lupulus extract and reduced significantly compared with the controls by all other extracts. Suppression of feeding was caused by all extracts at 200 g kg(-1), with V. songaricum providing 91% reduction in feeding duration. Rejection behaviour, in which larvae did not return to the leaf after their interaction with it, was rare on 2 g kg(-1) extracts but seen in over 60% of larvae on 20 g kg(-1) extracts and over 80% on 200 g kg(-1) extracts. The present results demonstrate that these extracts have significant ability to protect potato leaves for up to 24 h by prevention of feeding behaviour by L. decemlineata. Further studies are needed to determine the potential of these plant extracts, or their active components, for use in biologically based pest management strategies.     

Electrophysiological and behavioural responses of Pityophthorus pubescens (Coleoptera: Scolytinae) to (E,E)‐α‐farnesene, (R)‐(+)‐limonene and (S)‐(−)‐verbenone in Pinus radiata (Pinaceae) stands in northern Spain

BACKGROUND: Some twig beetles in the genus Pityophthorus (Coleoptera: Scolytinae) may vector pitch canker disease Fusarium circinatum (Niremberg & O'Donnell) of Pinus spp. (Pinaceae). Because Pityophthorus pubescens (Marsh.) has been found to be associated with F. circinatum in the Basque Country (northern Spain), various experiments were conducted to assess the beetle's behavioural responses to (E, E)‐α‐farnesene, (R)‐(+)‐limonene and (S)‐(?)‐verbenone to develop a potential inhibitor to host attraction. These experiments comprise electroantennographic and double‐choice olfactometer tests, as well as field assays in Pinus radiata D. Don stands. RESULTS: Both sexes of P. pubescens showed similar electroantennographic responses to different doses (from 1 ng to 1 µg in decadic steps) of each individual compound, with depolarisations to (S)‐(‐)‐verbenone (100 ng) being similar to those of the aggregation pheromone (+)‐trans‐pityol. In olfactometer assays, both sexes were significantly attracted to (+)‐trans‐pityol, but the attraction was reduced when increasing amounts of the chemicals were added to the pheromone. Particularly relevant was the repellent effect induced by (S)‐(?)‐verbenone at 1 ng dose and higher. In the field, (E, E)‐α‐farnesene, (R)‐(+)‐limonene and (S)‐(?)‐verbenone reduced significantly the number of beetles attracted to (+)‐trans‐pityol and racemic trans‐pityol, with (S)‐(?)‐verbenone being the most effective. CONCLUSIONS: (S)‐(?)‐Verbenone showed an interesting potential for use in the protection of P. radiata stands. A potentially effective strategy, which could be implemented in further, more in‐depth studies, could involve the use of this semiochemical as repellent and (+)‐trans‐pityol‐baited traps as attractant in a ‘push‐pull’ strategy. Copyright © 2012 Society of Chemical Industry     

Potato virus X (PVX) resistance in tomato cultivars

Understanding how birds detect and react to deterrent methods which are employed to protect structures is important both for the effective control of property damage, and to ensure that human health and safety are not compromised. One such device is a shock strip that causes slight pain to birds when they use a perch. Our aims were to determine: (1) the efficacy of a shock strip to flocks of Brown-headed Cowbirds (Molothrus ater), and Rock Pigeons (Columba livia); (2) the length of time to extinction of effect; (3) whether members of a flock show a behavioural response to treatment; and (4) whether the birds habituate to the treatment. When activated, shock strips were effective in displacing birds from treated areas. Birds had to experience the treatment; there was no discernible indication of flock members reacting to affected birds. When strips were deactivated after an initial period of activation, birds required more than 2 hours to return to treated areas. No habituation was observed. Because birds had to experience the shock, reduced coverage of a structure or use of sham devices to lower costs is considered inadvisable.     

Contradictions in host plant resistance to pests: spider mite (Tetranychus urticae Koch) behaviour undermines the potential resistance of smooth-leaved cotton (Gossypium hirsutum L.)

BACKGROUND: Two‐spotted spider mites (Tetranychus urticae Koch) oviposit near leaf veins or in leaf folds on the undersides of cotton (Gossypium hirsutum L.) leaves where the humid boundary layer offers protection from desiccation. The authors predicted that the boundary layer of glabrous cotton leaves should be shallower than that of hairy leaves, providing some resistance to mites. The dynamics of mite populations, leaf damage, leaf gas exchange and crop yield on two leaf hair isolines (smooth versus hairy) in two genetic backgrounds was assessed. RESULTS: Mite colonies developed faster on the hairy leaf isolines, but leaf damage per mite was higher in smooth leaf isolines, indicating more intense damage. A 50% reduction in photosynthesis on the hairy isolines required 1.8 times more mites than smooth leaves. The yield of cotton was reduced in + mite treatments, but the magnitude of reduction was similar for hairy and smooth isolines. CONCLUSION: Paradoxically, the relative inhospitality of glabrous leaves may have induced mites to concentrate in protected leaf sections, causing more localised and more severe damage, negating the yield benefits from fewer mites. These results highlight interactions between leaf microenvironment, pest behaviour and plant productivity that may have implications for other instances of plant resistance. Copyright © 2010 Society of Chemical Industry     

Epidemiology of Verticillium dahliae on olive (cv. Picual) and its effect on yield under saline conditions

The epidemiology of Verticillium dahliae and its effect on yield was studied for 3 years in three plots of olive cv. Picual, planted in soil previously cropped with highly susceptible V. dahliae host plants and irrigated with saline water. Disease incidence increased 2·2-, 2·6- and 1·5-fold in plots 3A, 9A and 9C, respectively, within 39, 25 and 15 months of the first record taken. The highest severities were recorded in spring 2001 (4·0, 5·3 and 5·4 on a scale of 2–10, respectively). Disease incidence and severity increased during winter–spring and decreased during summer. Seasonal changes were also observed in the isolation of V. dahliae ; the highest isolation rates in diseased trees were in winter (34%) and spring (45%), and the lowest were in autumn and summer (19–20%). Verticillium dahliae was isolated on an average of 27, 28 and 19% from the bottom, middle and top of the tree canopy, respectively, and was isolated from trees with and without symptoms. The fruit yield from diseased trees was reduced by an average of 75% in comparison with symptomless trees in plot 3A each year. A similar yield reduction (89%) was recorded in plot 9A in 2000. The severe expression of the disease and its effect on yield in the present study could be due to the fact that the orchard was planted in infested soil, and that saline irrigation probably exacerbates the problem.     

Helicoverpa armigera preference and performance on three cultivars of short-duration pigeonpea (Cajanus cajan): the importance of whole plant assays

BACKGROUND

Helicoverpa armigera is a major pest of pigeonpea (Cajanus cajan). Efforts to develop pigeonpea varieties resistant to H. armigera attack have been met with limited success, despite reports of high levels of resistance to H. armigera in wild relatives of pigeonpea and reports of low to moderate levels of resistance in cultivated varieties. Here we examined H. armigera oviposition preference and larval performance on whole plants of three cultivars of short-duration pigeonpea: a susceptible control (ICPL 87) and two cultivars with purported host–plant resistance (ICPL 86012 and ICPL 88039).

RESULTS

In our no-choice oviposition experiment, H. armigera laid similar numbers of eggs on all three cultivars tested, but under choice conditions moths laid slightly more eggs on ICPL 88039. Larval growth and development were affected by cultivar, and larvae grew to the largest size (weight) and developed fastest on ICPL 86012. Moths laid most of their eggs on floral structures, sites where subsequent early instar larvae overwhelmingly fed. Experimentally placing neonate larvae at different locations on plants demonstrated that larvae placed on flowers experienced greater survival, faster development, and greater weight gain than those placed on leaves. The type and density of trichomes (a potential resistance trait) differed among cultivars and plant structures, but larvae selected to feed at sites where trichomes were absent.

CONCLUSION

Future work examining host–plant resistance against H. armigera should incorporate the behavioural preference of moths and larvae in experiments using whole plants as opposed to bioassays of excised plant parts in Petri dishes. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Feeding behaviour as a limiting step in insecticide absorption for the wireworm Agriotes sp. (Coleoptera: Elateridae)

The fipronil control of wireworms field populations (larval Agriotes sp., Coleoptera: Elateridae) is difficult because of the low integumental penetration rates of this insecticide into the target larval body. The main way of insecticide absorption being associated with food, analysis of the larval feeding behaviour is of key importance for designing a strategy of dietary chemical control of those subterranean pests. In this purpose, a standard method for assessing the long-term survival of field specimens in the laboratory was developed together with experimental designs for investigating food searching and choosing by larvae. Larval biological performances under those laboratory conditions were checked monthly. Three criteria were taken into account for measures: the duration of individual survival, the gain in average body weight, and the moulting rhythm. Experimentation revealed that seed flour was highly desired by larvae and that larval feeding choice was affected over short distances only. This suggests the involvement of dietary preference rather than attractivity in the larval feeding behaviour. This implies that, at the operational step, insecticide had better be associated to food, either as a coating on the seeds, or inside preferred baits.     

Biological traits and feeding capacity of Agriotes larvae (Coleoptera: Elateridae): A trial of seed coating to control larval populations with the insecticide fipronil

Until recently, the chemical control of phytophagous larvae of the genus Agriotes was exclusively achieved through soil treatment with insecticides. Under such conditions, the larvae receive the active ingredient (a.i.) by integumental penetration whilst moving through the subsurface soil. The selectivity of such treatments is only based on the biochemical selectivity of the a.i. which is generally very low across soil invertebrates. More recent a.i.s from new chemical families such as fiprols show not only a new biochemical mode of action but also a particular mode of penetration which is restricted to the digestive pathway. This allows a new type of selectivity, based on penetration after feeding, when the a.i. is associated with food. We demonstrate that Agriotes species, which are important pests for several crops, feed almost exclusively on the seeds of plant species. This dietary selectivity is based on appetency, rather than attractivity. The appetent molecules are mostly present in the seed’s acetonic powders but there is also an effect of the small lipophilic molecules extracted by the solvent. Taking into account the meal size and the feeding behaviour of the larvae, we show that when an insecticide such as fipronil is associated with food as a seed coating, much lower amounts of a.i. are required than those necessary in a full-soil treatment. The theoretical basis of this treatment, and limits to control Agriotes populations by such seed coatings are discussed.     

Impact of Bacillus thuringiensis strains on survival,reproduction and foraging behaviour in bumblebees (Bombus terrestris)

BACKGROUND: Bacillus thuringiensis (Bt) and its protein crystals are used worldwide, either as a spray or when expressed in transgenic crops, for the control of pest insects. However, owing to their intensive use, there exists a debate regarding the involvement of this microbial insecticide in bee colony losses. In this study, in a tiered approach using laboratory microcolonies, an evaluation was made of the potential lethal and sublethal hazards on colony reproduction and foraging behaviour of workers of the bumblebee Bombus terrestris (L.) of two commercial Bt strains: kurstaki (Dipel^®) and aizawai (Xentari^®). Bumblebees, like honey bees, are intensively used in modern agriculture for pollination and fulfil a crucial role in the natural ecosystem. RESULTS: Exposure of bumblebees dermally or via treated pollen to either of the two Bt formulations at their field recommended rates (0.1%) caused no reduction in survival. However, when applied in the feeding sugar water, aizawai killed all workers at a concentration of 0.1%, but this lethal effect was lost at 0.01%. With respect to reproductive effects, kurstaki was harmless, while aizawai at 0.1% delivered in the feeding sugar water and pollen reduced reproduction by 100 and 31% respectively. Lower doses of 0.01% aizawai in the sugar water showed no more effect. In addition, kurstaki at 0.1% and aizawai at 0.01% in the feeding sugar water did not impair the foraging behaviour, resulting in normal nest colony performance. CONCLUSION: The results with kurstaki and aizawai demonstrated that, in general, the Bt strains are safe to B. terrestris bumblebees, although in some cases there were detrimental effects that depended on strain and route of exposure. In addition, the authors believe that to draw firm conclusions regarding the hazards of Bt to bumblebees would require more information on relevant concentrations of Bt products in the environment. Hence, routine testing for lethal and sublethal effects is recommended to ascertain combined use of Bt products and bumblebees in modern agriculture. Copyright © 2009 Society of Chemical Industry     

Plant volatile compounds shorten reaction time and enhance attraction of the codling moth (Cydia pomonella) to codlemone

BACKGROUND: The codling moth is the most serious pest of deciduous tree fruit (apples, pears, crabapples, walnuts, quince) worldwide. The high frequency of insecticide treatments per season has resulted in breakdown of codling moth control owing to insecticide resistance. As an alternative, integrated pest management includes mating disruption to achieve population suppression in orchards. Under this scheme, the sex pheromone of the codling moth, (E, E)‐8,10‐dodecadien‐1‐ol (codlemone), is released from dispensers in crops to hinder mating by luring males. Increasing the attractiveness of codlemone formulations to codling moth males can be regarded as a key to increasing the efficacy of mating disruption. With this aim, the effects of adding plant volatiles on the behavioural responses of codling moth males to codlemone were tested. RESULTS: Adding R(+)‐limonene, linalool, (E)‐β‐farnesene or ethyl (E, Z)‐2,4‐decadienoate to codlemone significantly increases the proportion of males flying to the pheromone source in a wind tunnel. The response level is equivalent to that of males responding to females releasing codlemone. Using real‐time recordings, it is shown how these four plant products also shorten the response time of males to codlemone under the behavioural criteria time to activation, time till upwind flight is induced and time to pheromone source contact. CONCLUSION: Shortening the response time and increasing source location by males of dispensers releasing codlemone with R(+)‐limonene, linalool, (E)‐β‐farnesene or ethyl (E, Z)‐2,4‐decadienoate added would enhance mating disruption through better engagement of males with dispensers, to the detriment of females. Copyright © 2011 Society of Chemical Industry