Host Plant Selection Behavior Research Articles

Plant growth-promoting rhizobacteria modulate induced corn defense against Spodoptera litura (Lepidoptera: Noctuidae).

Common cutworm, Spodoptera litura is an important pest of corn causing significant crop yield loss. Synthetic insecticides have mostly been used to combat this pest, raising human and environmental health concerns. Plant growth-promoting rhizobacteria (PGPR) could compensate for or augment the harmful effects of agrochemicals. Herein, we aimed to assess whether PGPR-induced defenses in corn plants impact the host-plant selection behavior of S. litura. Headspace volatile organic compounds were analyzed using gas chromatography-mass spectrometry. Larvae fed inoculated corn exhibited lower weights and relative growth rate than noninoculated plants. Under choice experiments, PGPR-treated plants significantly reduced percentage leaf damage area and oviposition rate compared to untreated plants. Volatile organic compound ratio emission varied significantly between control and PGPR treatments, which, in part, explains feeding and oviposition deterrence in PGPR-treated plants. The results demonstrate that PGPR inoculation can enhance corn resistance to S. litura, making it a promising candidate for crop protection strategies.

Hesperidin as a Species-Specific Modifier of Aphid Behavior.

Hesperidin is a highly bioactive natural flavonoid whose role in ecological interactions is poorly known. In particular, the effects of hesperidin on herbivores are rarely reported. Flavonoids have been considered as prospective biopesticides; therefore, the aim of the present study was to examine the influence of hesperidin on the host plant selection behavior of three aphid (Hemiptera: Aphididae) species: Acyrthosiphon pisum Harrris, Rhopalosiphum padi (L.), and Myzus persicae (Sulz.). The aphid host plants were treated with 0.1% and 0.5% ethanolic solutions of hesperidin. Aphid probing behavior in the no-choice experiment was monitored using electropenetrography and aphid settling on plants in the choice experiment was recorded. The results demonstrated that hesperidin can be applied as a pre-ingestive, ingestive, and post-ingestive deterrent against A. pisum, as an ingestive deterrent against R. padi, and as a post-ingestive deterrent against M. persicae using the relatively low 0.1% concentration. While in A. pisum the deterrent effects of hesperidin were manifested as early as during aphid probing in peripheral plant tissues, in M. persicae, the avoidance of plants was probably the consequence of consuming the hesperidin-containing phloem sap.

Behavioral and Electrophysiological Study on Eight Japanese Papilio Species with Five Hostplant Volatiles and Linalool

An electroantennogram (EAG) technique compared the antennal olfactory responses by both sexes of eight Japanese Papilio species with known host plants in laboratory experiments. Papilio species were collected from Honshû and Kyûshû (Japanese islands). The behavioral responses to volatile leaf substances from Citrus deliciosa, Zanthoxylum ailanthoides, Phellodendron amurense, Orixa japonica, and Foeniculum vulgare were examined in laboratory experiments. Individual EAG reactions were recorded. The results were very similar to the empirical field observations. The electrophysiological results of both sexes showed that the volatile substances released from non-preferred plants mainly elicited more significant EAG responses than the volatile substances from preferred host plants. Moreover, we performed behavioral experiments using eight female butterflies and their responses to five host plant species. An association between host plant selection behavior and taxonomical classification exists within the Papilio genus. The EAG responses were small when exposed to the plants with high scores in the behavioral experiments. Host plant preference patterns seem to be related to the volatile substances within the host plants. The butterflies responded to Linalool in both the behavioral and electrophysiological experiments.

Environmentally acquired chemical camouflage affects Pieris brassicae L. host plant selection and orientation behaviour of a larval parasitoid

Environmentally acquired chemical camouflage is a phenomenon, where a plant growing close to a strong volatile organic compound (VOC) emitter will adsorb and re-emit the VOCs produced by the neighbouring plant. The re-emitted volatile bouquet may resemble more the VOC composition of the neighbour than plant’s own typical odour, and thus act as chemical camouflage against insect detection, potentially simultaneously providing associational resistance towards herbivory. We exposed a pest-sensitive horticultural crop, Brassica oleracea var. italica (broccoli) cv. Lucky, to the volatiles emitted by Rhododendron tomentosum [RT] twigs and assessed the host selection by ovipositing females and larval instars of the major caterpillar pest Pieris brassicae between RT-exposed and control plants. Potential impact of RT exposure on herbivore natural enemies was studied using behavioural tests with a parasitoid wasp Cotesia glomerata. P. brassicae females laid significantly less eggs and egg clusters were fewer on RT-exposed plants at both night-time (6 °C) and daytime (22 °C) temperatures. Larvae preferred leaves from control plants over RT-exposed plants at both temperatures. Preceding RT-exposure did not disturb orientation of parasitoid wasp Cotesia glomerata females towards B. oleracea plants damaged by its host P. brassicae. However, host-damaged control plants were favoured by the parasitoid over RT-exposed, host-damaged plants. Our results suggest that companion plant based chemical camouflage as a mechanism of pest suppression could be developed as an additional tool for the integrated pest management toolbox in agriculture.

Ultra structural study on different sensory structure and some associated body parts of mango mealy bug, Drosicha mangiferae (G.) by scanning electron microscopy

Ultra structural study on different sensory structure and some associated body parts of mango mealy bug, Drosicha mangiferae (G.) by scanning electron microscopy

Host plant selection and virus transmission by Rhopalosiphum maidis are conditioned by potyvirus infection in Sorghum bicolor

Many plant viruses are significant pathogens that are able to utilize arthropod vectors to infect a vast range of host plants, resulting in serious economic damage to world food crops. One such crop is Sorghum bicolor, grain sorghum, which is the fifth most important global cereal crop, it is grown for human consumption, animal feed, and biofuel. In this study, the Potyviruses Johnsongrass mosaic virus (JGMV), Maize dwarf mosaic virus (MDMV), Sugarcane mosaic virus (SCMV), and Sorghum mosaic virus (SRMV) were tested for their rates of transmission into tissues of S. bicolor by the corn leaf aphid, Rhopalosiphum maidis. In addition, virus infected and non-infected S. bicolor plants were assessed for their effects on R. maidis host plant selection behavior. Further, the propagation of each virus (viral ssRNA copy number) in infected plants was determined using qPCR amplification of viral coating protein gene fragments. The mean rate of JGMV transmission into S. bicolor plants by R. maidis was significantly lower than transmission of MDMV, SCMV, and/or SRMV. Sorghum bicolor plants infected with MDMV, SCMV or SRMV also attract significantly more R. maidis than non-infected plants. JGMV-infected plants do not effect a similar change in R. maidis plant choice preference. The preference of non-viruliferous R. maidis toward S. bicolor plants infected with MDMV, SCMV or SRMV, and lack of such attraction by JGMV-infected plants may play a role in virus transmission strategy and efficiency by the vector.

New insight into the behaviour modifying activity of two natural sesquiterpenoids farnesol and nerolidol towards Myzus persicae (Sulzer) (Homoptera: Aphididae).

The effect of structurally related sesquiterpenoids (E,E)-farnesol and cis-nerolidol on the host-plant selection behaviour of the peach potato aphid Myzus persicae (Sulz.) was evaluated using electrical penetration graph (EPG) technique. No repellent effects of (E,E)-farnesol and (Z)-nerolidol to M. persicae were found but aphid probing activities on (E,E)-farnesol- and cis-nerolidol-treated plants were restrained. During non-phloem phases of probing, neither (E,E)-farnesol nor (Z)-nerolidol affected the cell puncture activity. On (E,E)-farnesol-treated plants, the total duration of phloem phase, the mean duration of individual sustained ingestion periods were significantly lower, and the proportion of phloem salivation was higher than on control plants. On (Z)-nerolidol-treated plants, the occurrence of the first phloem phase was delayed, and the frequency of the phloem phase was lower than on control plants. The freely moving aphids were reluctant to remain on (E,E)-farnesol- and (Z)-nerolidol-treated leaves for at least 24 h after exposure. (E,E)-Farnesol and (Z)-nerolidol show complementary deterrent properties, (E,E)-farnesol showing ingestive and post-ingestive activities and nerolidol showing pre-ingestive, ingestive, and post-ingestive deterrent activities.

Higher plasticity in feeding preference of a generalist than a specialist: experiments with two closely related Helicoverpa species

Herbivorous insects have been categorized as generalists or specialists depending on the taxonomic relatedness of the plants they use as food or oviposition substrates. The plasticity in host plant selection behavior of species belonging to the two categories received little attention. In the present work, fifth instar caterpillars of the generalist herbivore Helicoverpa armigera and its closely related species, the specialist Helicoverpa assulta, were fed on common host plants or artificial diet, after which their feeding preference was assessed individually by using dual - and triple- plant choice assays. Results show both the two Helicoverpa species have a preference hierarchy for host plants. Compared to the fixed preference hierarchy of the specialist H. assulta, the generalist H. armigera exhibited extensive plasticity in feeding preference depending on the host plant experienced during larval development. Whereas the specialist H. assulta exhibited a rigid preference in both dual and triple-plant choice assays, our findings demonstrate that the generalist H. armigera expressed stronger preferences in the dual-plant choice assay than in the triple-plant choice assay. Our results provide additional evidence supporting the neural constraints hypothesis which predicts that generalist herbivores make less accurate decisions than specialists when selecting plants.

Cover Caption

Nezara viridula (Linnaeus) is a cosmopolitan plant‐feeding stink bug species known by several different common names around the world including the southern green stink bug, southern green shield bug, or green vegetable bug. Although it commonly feeds on legumes, this species can also be an important pest of other plants including cotton on which it uses its piercing‐sucking mouthparts to feed on developing reproductive structures and vector pathogens in the process. There is a growing appreciation of the role of facultative fungal endophytes in conferring protection to plants from a variety of insect herbivores. The inoculation of cotton with specific fungal endophytes can affect the host plant selection behavior of stink bugs and other important hemipteran pests (see pages 1003‐1014). Photo by Cesar U. Valencia.

Ultrastructure and distribution of antennal sensilla of the chilli thrips Scirtothrips dorsalis hood (Thysanoptera: Thripidae).

The chilli thrips, Scirtothrips dorsalis Hood, is a serious pest of numerous important vegetable and ornamental crops. Various signals, especially phytochemical cues, determine the behavior of the phytophagous thrips at host selection. The sensory abilities of S. dorsalis are poorly understood although the antennae of adult are known to possess important sensory structures in orther insects. In this study, the morphology, distribution, and ultrastructure of the antennal sensilla of the S. dorsalis were examined by using scanning and transmission electron microscopy. Microscopy observations revealed that adult male and female S. dorsalis possess filiform antennae. Each antenna comprises a scape, a pedicel, and a flagellum composed of six segments without clear sexual dimorphism in the number and distribution of antennal sensilla. The scape and pedicel exhibit Böhm's bristles, sensilla chaetica, and sensilla campaniform. The external structures of these organs reveal their mechanosensory function. In the flagellum, the most represented sensilla are the multiporous sensilla basiconica, which can be divided into three types of single-walled olfactory sensilla; three types of sensilla chaetica with mechanosensory and gustatory functions; sensilla coeloconica, which possess hollow cuticular spoke channels and represent double-walled olfactory sensilla; sensilla capitula and sensilla cavity with thermo-hygrosensory functions; and aporous sensilla trichodea with smooth cuticula and mechanosensory function. The putative function of described sensilla is discussed in ralation to host plant selection behavior of S. dorsalis.

Expression map of a complete set of gustatory receptor genes in chemosensory organs of Bombyx mori

Most lepidopteran species are herbivores, and interaction with host plants affects their gene expression and behavior as well as their genome evolution. Gustatory receptors (Grs) are expected to mediate host plant selection, feeding, oviposition and courtship behavior. However, due to their high diversity, sequence divergence and extremely low level of expression it has been difficult to identify precisely a complete set of Grs in Lepidoptera. By manual annotation and BAC sequencing, we improved annotation of 43 gene sequences compared with previously reported Grs in the most studied lepidopteran model, the silkworm, Bombyx mori, and identified 7 new tandem copies of BmGr30 on chromosome 7, bringing the total number of BmGrs to 76. Among these, we mapped 68 genes to chromosomes in a newly constructed chromosome distribution map and 8 genes to scaffolds; we also found new evidence for large clusters of BmGrs, especially from the bitter receptor family. RNA-seq analysis of diverse BmGr expression patterns in chemosensory organs of larvae and adults enabled us to draw a precise organ specific map of BmGr expression. Interestingly, most of the clustered genes were expressed in the same tissues and more than half of the genes were expressed in larval maxillae, larval thoracic legs and adult legs. For example, BmGr63 showed high expression levels in all organs in both larval and adult stages. By contrast, some genes showed expression limited to specific developmental stages or organs and tissues. BmGr19 was highly expressed in larval chemosensory organs (especially antennae and thoracic legs), the single exon genes BmGr53 and BmGr67 were expressed exclusively in larval tissues, the BmGr27–BmGr31 gene cluster on chr7 displayed a high expression level limited to adult legs and the candidate CO2 receptor BmGr2 was highly expressed in adult antennae, where few other Grs were expressed. Transcriptional analysis of the Grs in B. mori provides a valuable new reference for finding genes involved in plant-insect interactions in Lepidoptera and establishing correlations between these genes and vital insect behaviors like host plant selection and courtship for mating.

Effect of mineral oils on host plant selection and probing behavior of Rhopalosiphum padi

AbstractAphids that colonize and reproduce on potato are some of the most efficient vectors of Potato virus Y (PVY) (Potyviridae: Potyvirus), and hence these aphids have been the focus of the majority of studies to date. However, other non‐colonizing aphids can also function as vectors. Mineral oil is the only product available to growers that effectively prevents the spread of PVY in potato seed production. Most previous studies focused on the effect of mineral oil on the behavior of aphids on their preferential host plant, and consequently there is a lack of information for non‐colonizing aphids on potato plants. The objective of this study was to determine the effect of spraying potatoes with one of two mineral oils, Superior 70 or Vazyl‐Y, on host selection and probing behavior of the non‐colonizing aphid Rhopalosiphum padi (L.) (Hemiptera: Aphididae). The electrical penetration graph (EPG) technique, combined with ethological observations, determined that there was no difference in R. padi behavior on potato plants treated with Superior 70. However, there were few significant changes in R. padi behavior on plants sprayed with Vazyl‐Y, including a delay in the initiation of stylet penetration and an increase in the duration of xylem sap ingestion. These new data support previous results and confirm that the mode of action of mineral oil in the reduction of the spread of PVY is not solely due to the modification of the behavior of aphids.

Artificial Damage Induction in the Leaves of Chilli Plants Leads to the Release of Volatiles that Alter the Host Plant Selection Behaviour of Bemisia tabaci (Hemiptera: Aleyrodidae)

Artificial Damage Induction in the Leaves of Chilli Plants Leads to the Release of Volatiles that Alter the Host Plant Selection Behaviour of Bemisia tabaci (Hemiptera: Aleyrodidae)

Reciprocal crosstalk between jasmonate and salicylate defence-signalling pathways modulates plant volatile emission and herbivore host-selection behaviour.

The jasmonic acid (JA) and salicylic acid (SA) signalling pathways, which mediate induced plant defence responses, can express negative crosstalk. Limited knowledge is available on the effects of this crosstalk on host-plant selection behaviour of herbivores. We report on temporal and dosage effects of such crosstalk on host preference and oviposition-site selection behaviour of the herbivorous spider mite Tetranychus urticae towards Lima bean (Phaseolus lunatus) plants, including underlying mechanisms. Behavioural observations reveal a dynamic temporal response of mites to single or combined applications of JA and SA to the plant, including attraction and repellence, and an antagonistic interaction between SA- and JA-mediated plant responses. Dose-response experiments show that concentrations of 0.001mM and higher of one phytohormone can neutralize the repellent effect of a 1mM application of the other phytohormone on herbivore behaviour. Moreover, antagonism between the two signal-transduction pathways affects phytohormone-induced volatile emission. Our multidisciplinary study reveals the dynamic plant phenotype that is modulated by subtle changes in relative phytohormonal titres and consequences for the dynamic host-plant selection by an herbivore. The longer-term effects on plant-herbivore interactions deserve further investigation.

Vector activity of three aphid species (Hemiptera: Aphididae) modulated by host plant selection behaviour on potato (Solanales: Solanaceae)

SummaryViral diseases non-persistently transmitted by aphids are of great economic importance in several annual crops. Transmission efficiency of these non-persistent phytoviruses is dependant on vector efficiency (i.e. vector intrinsic ability to transmit the virus) but also on the vector activity that implies the early steps of aphid host plant selection process (i.e. brief intracellular stylet punctures after landing) and to their interplant movement ability. In Europe, Macrosiphum euphorbiae (Thomas 1878) is considered as one of the most serious virus vectors on potato (Solanum tuberosum L. 1753). Nevertheless, several alate aphid species that do not colonise potato plants are trapped in potato crops. Therefore, we investigated, through laboratory experiments, vector activity of one potato colonising aphid, M. euphorbiae, and two non-colonising potato aphids, the bird cherry-oat aphid Rhopalosiphum padi (L. 1758) and the pea aphid Acyrthosiphon pisum (Harris 1776). A settling experiment was used to evaluate dispersal activity, and the electrical penetration graph (EPG) technique was used to investigate probing activity on potato plants. Results showed that M. euphorbiae exhibited a better vector activity than other two aphid species in terms of landing and probing. By contrast, interplant movements were only recorded on non-colonising aphids, suggesting a better vector activity than M. euphorbiae in terms of locomotive behaviour. These data confirm the involvement of A. pisum and R. padi in the spread of non-persistent viruses.

Host plant selection and oviposition behaviour of whitefly Bemisia tabaci (Gennadius) in a mono and simulated polyculture crop habitat

The host plant selection, oviposition behaviour and survivorship of whitefly ( Bemisia tabac i (Gennadius) was evaluated in green house. Three host plants cultivars namely: Brinjal ( Solanum malagna ), chilli ( Capsicum annuum ) and tomato ( Solanum lycopersicu m) were placed in a multiple crop habitat at 34 - 36°C, 70 - 80% relative humidity (RH) in a normal day light. There was a variation of morphological characteristic among host plants (smooth and thick trichome leaves) where all developmental stages of pest were given free choice of foraging. Although the host plants genus C. annum and S. lycopersicum were also the potential host of B. tabaci but in the presence of S. malagna, the attack rate remains minimum on both the host plants. The feeding and egg laying was significantly higher on S. malagna L . leaves as compare to other two host plants in the open arena. S malagna L. was also preferred when pest was tested in confined cages for free choice probing on capsicum and S. malagna L. There was no significant but a slight difference in survivorship of all developmental stages of whitefly when Brinjal and Chilli and then Brinjal and tomato from two different experimental arenas were compared. There was no host plant varietal effect on the overall developmental time from egg eclosion to the adult. The leaves of S. malagna with thick trichomes were chosen significantly more higher for egg laying compared to other host plants. The morphological characters and plant architecture contribute to higher densities of adult whitefly (wf) compared to new leaves. No symptoms of viral infection has been observed on the chilli with Brinjal, whereas, the same variety of chilli was reasonably infected with virus in chilli monocrop arena. Key words: Multiple cropping, host plant selection, oviposition fecundity, intrinsic rate of increase.

Host plant selection behaviour of Chilo partellus and its implication for effectiveness of a trap crop

Female lepidopterans can display a hierarchy of preference among potential host species, a trait thought to arise from the balance between attractants and deterrents to which the insects respond. Host plant ranking by moths and larvae of Chilo partellus Swinhoe (Lepidoptera: Crambidae), an important pest of cereals in Africa, was investigated, and whether eggs deposited on specific host plants yield larvae of particular host preferences. Trap plants are used in management of this pest. However, any 'disagreement' in host ranking between moths and larvae could potentially reduce effectiveness of trap crops as larvae emigrate to the main crop from the parent's preferred trap plant. We also investigated whether host plant preference is influenced by the diet upon which larvae fed as part of an integrated assessment of the relationship between host plant selection and learning in C. partellus. Five host plants (all Poaceae) were used: maize (Zea mays L.), sorghum (Sorghum bicolor Moench), Napier grass (Pennisetum purpureum Schumach), and two varieties of signal grass [Brachiaria brizantha (A. Rich.) Stapf], viz., local (henceforth signal grass) and improved ('Mulato'). In multiple choice tests, C. partellus female moths preferentially oviposited on Napier grass, followed by sorghum, maize, and signal grass, and least preferred 'Mulato'. Larvae however equally orientated and settled on leaf cuts of maize, sorghum, signal grass, and Napier grass, but least preferred 'Mulato'. Moreover, eggs from specific host plants did not yield larvae of particular host preferences. Furthermore, oviposition preference was not altered by the larval food. These results imply only a slight 'disagreement' in host ranking behaviour between moths and larvae, which is beneficial for trap cropping as larvae would not 'reject' the trap plant and appreciably disperse to the neighboring plants. Moreover, absence of larval learning behaviour indicates that regardless of the larval food C. partellus moths would still be attracted to the selected trap plant.

A picky palate? The host plant selection of an endangered June beetle

Precise information about endangered species, in particular identifying their resources requirements, is needed to identify areas that might support populations. Little is known about the endangered Mount Hermon June Beetle (Polyphylla barbata) found only within Zayante soils region of Santa Cruz County, California. We investigated the beetle’s host plant selection, habitat association and mating behavior between June 2004 and September 2005. We identified angiosperm and Pteridophyta phyla, and fungi within the frass pellets of Mount Hermon June Beetle larvae demonstrating that they are not specialist feeders but are microhabitat specialists. Larval species was confirmed by DNA analysis. Significant differences were found in vegetation assemblages between regions where the Mount Hermon June Beetle did and did not occur for Chorizanthe pungens var. hartwegiana, and bare ground.

Behavior of Bird Cherry-Oat Aphid and Green Peach Aphid in Relation to Potato Virus Y Transmission

Potato virus Y is transmitted to potato in a nonpersistent manner by many aphid species, some of which do not colonize this crop. The behavior of bird cherry-oat aphid, Rhopalosiphum padi (L.) on potato, Solanum tuberosum L., a plant species that is not colonized by this aphid, was described and compared with that of the potato-colonizing green peach aphid, Myzuspersicae (Sulzer). A higher proportion of winged morph of R. padi than M. persicae left the plant, but aphids that stayed in contact with the plant took the same mean time to initiate the first probe and it lasted the same mean time compared with M. persicae. Electronic penetration graph technique was used to study the probing behavior of the aphids during Potato virus Y (family Potyviridae, genus Potyvirus, PVY) transmission tests. Transmission rate decreased from 29 to 8% when the acquisition time increased from 5 min of continuous probing to 1 h with M. persicae, but it remained low (2 and 1%) with R. padi. Most of the difference in transmission rate between acquisition time with M. persicae and between aphid species was related to the change in the time and behavior taking place between the last cell puncture of the acquisition phase to the first cell puncture of the inoculation phase. Results presented here clearly demonstrated the importance of host plant selection and probing behavior in the transmission of nonpersistent plant viruses. They also stress the need to consider the behavior of the aphid in the design of laboratory tests of virus vector efficacy.

Physiological state of female and light intensity affect the host-plant selection of carrot psyllid, Trioza apicalis (Hemiptera: Triozidae)

We have studied the effect of different light gradient regimes on host-plant selection of the carrot psyllid, Trioza apicalis Forster. In both a strong and a weak light gradient, carrot psyllids preferred a carrot leaf placed in higher light intensity. When the choice was between the host (carrot Daucus carota L.) and a non-host (barley Hordeum vulgare L.) virgin adults settled significantly more often on non-host in higher light intensity than on carrot in lower light intensity. In a weak light gradient, none of the gravid females settled on a non-host. In an experiment without light gradient, gravid females showed a preference for carrot, whereas virgin females settled approximately equally on Norway spruce Picea abies Karst. (winter shelter plant) and carrot. Our results show that virgin and gravid individuals have different host-plant selection behaviour, and that they are sensitive to small differences in light intensity. Both factors can create a source of variation in behavioural assays, and should be taken into consideration in future experiments with this and probably also related species. Our results suggest that carrot psyllids can utilize visual cues (light intensity or wavelength) in host-plant selection, and the role of visual cues should be more thoroughly studied.