Avoidance of occupied hosts by the Hessian fly: oviposition behaviour and consequences for larval survival

Abstract 1. Unoccupied wheat plants and wheat plants occupied by conspecific eggs or larvae were presented to ovipositing female Hessian flies in choice tests.
2. The presence of conspecific eggs on the leaf surfaces of wheat plants did not appear to have any effect on the responses of ovipositing Hessian fly females.
3. The presence of conspecific larvae at the base and nodes of wheat plants for 1, 6, or 11 days had significant effects on Hessian fly oviposition. Eggs oviposited on plants were inversely proportional to larval densities and days of larval occupation.
4. Feeding by Hessian fly larvae is associated with several changes in wheat plants. One of these changes, the growth arrestment of the plant, was measured by recording the heights of plants used in oviposition tests. Plant heights were inversely proportional to both larval densities and days of occupation. Plant heights were directly proportional to eggs oviposited on plants.
5. The consequences of adult female avoidance of plants occupied by conspecific larvae were investigated by allowing females to oviposit on unoccupied plants and 1-day, 6-day, and 11-day larval occupied plants, then scoring at the end of the first larval instar the survival of the offspring that resulted from this oviposition.
6. Survival during the first larval instar was 88% for the offspring of females that oviposited on unoccupied plants, decreasing to 82, 31, and 4% on the 1-day, 6-day, and 11-day occupied plant treatments. On these four plant treatments, a positive correlation was found between larval performance (i.e. survival) and the preferences of ovipositing females.
7. On the four plant treatments, relationships between first-instar larval density and first-instar larval survival varied significantly. On unoccupied plants, survival was inversely proportional to density. On plants oviposited on at 6 days of larval occupation, survival was directly proportional to density.     

Impact of plant architecture versus leaf quality on attack by leaf-tying caterpillars on five oak species

Because shelter-building herbivorous insect species often consider structural features of their host plants in selecting construction sites, their probability of attack is likely to be a function of some combination of plant architectural traits and leaf quality factors. We tested the hypothesis that plant architecture, in the form of the number of touching leaves, influences interspecific variation in attack by leaf-tying caterpillars in five species of sympatric Missouri oaks (Quercus). We compared colonization on control branches, in which both architecture and leaf quality were potentially important, with colonization on experimental branches for which we controlled for the effects of architecture by creating equal numbers of artificial ties. Colonization of artificial ties was highly correlated with natural colonization on neighboring control branches, suggesting that leaf quality factors and not architecture influenced interspecific variation in attack by leaf-tying caterpillars. Of the leaf quality factors measured (water, protein-binding capacity, nitrogen, specific leaf area, pubescence, and toughness), nitrogen was the most explanatory. With the exception of white oak, natural leaf tie colonization was positively correlated with nitrogen availability (ratio of nitrogen to protein-binding capacity), and negatively correlated with protein-binding capacity of leaf extracts. Both host plant species and subgenus oak influenced the community composition of leaf-tying caterpillars and the non-tying symbionts colonizing the ties. Host plant differences in leaf nitrogen content were positively correlated with pupal weight of one of two caterpillar species reared on all five host plant species. Thus, interspecific differences in nitrogen, nitrogen availability, and protein-binding capacity of leaf extracts are the best predictors at this time of interspecific differences in attack by leaf-tying caterpillars, in turn affecting their success on individual host plants in the laboratory.     

Ecological consequences of shelter sharing by leaf-tying caterpillars

A wide variety of insect herbivores construct and inhabit leaf shelters (ties, rolls, folds, and webs). Shelter construction can lead to a high rate of secondary occupation by other arthropods, including other species of constructors. The consequences for the inhabitants of secondarily occupying these shelters are currently unknown. In this study, we conducted field experiments to examine the fitness consequences (survival and attack by natural enemies) for caterpillars that (i) occupy a shelter with conspecifics vs. occur singly; and (ii) establish a new shelter vs. colonize a pre‐existing one. In addition, we conducted factorial laboratory experiments to test the hypothesis that caterpillars sharing shelters with conspecifics might have reduced construction costs (a potential benefit of shelter‐sharing or secondary occupation). Larvae of Psilocorsis quercicella Clemens (Lepidoptera: Oecophoridae) placed in white oak [Quercus alba L. (Fagaceae)] leaf ties alone or in groups of three had equal likelihood of survival from natural enemies. This same caterpillar species, however, had a higher disappearance rate when placed in pre‐existing leaf ties than when placed in newly formed ones, suggesting a potential cost of secondary colonization. A similar experiment with a closely related species [Psilocorsis cryptolechiella (Chambers)], however, failed to detect a cost of secondarily occupying shelters made on beech, Fagus grandifolia Ehrh. (Fagaceae). In the laboratory experiment, we found no evidence of shelter‐sharing benefits; rather larvae reared in shelters in groups of three had lower pupal mass (and thus lower potential fecundity) than larvae reared singly, suggesting a cost of shelter sharing. Moreover, groups of larvae forced to repeatedly construct new shelters tended to have reduced survival relative to the other treatment, suggesting that energetic constraints are more likely to reduce fitness when larvae cohabit shelters. Taken together, these results indicate that the common phenomenon of shelter sharing by leaf‐tying caterpillars has either neutral or negative effects for the occupants. The fact that these leaf‐tying caterpillars actually share shelters may simply reflect limited availability of oviposition sites.     

Oviposition decreased in response to enriched water: a field study of the pitcher-plant mosquito, Wyeomyia smithii

Abstract.  1. Environmental cues are known to influence oviposition behaviour in mosquitoes, with important consequences for larval survival and insect population dynamics. Enriched microhabitats have been shown to be preferred oviposition sites.
2. In a field experiment designed to determine whether ovipositing mosquitoes are sensitive to different levels of nutrient enrichment, new pitcher-plant ( Sarracenia purpurea ) leaves were opened and enriched with 0, 2, or 20 dead ants, and the number of pitcher-plant mosquito ( Wyeomyia smithii ) larvae resulting from subsequent oviposition were measured.
3. Oviposition rates were higher in leaves with low levels of enrichment (0 and 2 ants per leaf), although larval development was enhanced at the highest enrichment level.
4. Results suggest that, although these mosquito larvae are nutrient limited, ovipositing females preferentially avoid highly enriched leaves. This counterintuitive result may be due to low oxygen concentrations or a masked cue in enriched leaves, and contrasts with other oviposition studies.     

Conspecifics and Their Posture Influence Site Choice and Oviposition in the Damselfly Argia moesta

Finding a suitable oviposition site can be costly because of energy and time requirements, and ovipositioning can be dangerous because of the risk of predation and harassment by males. The damselfly Argia moesta oviposits, contact-guarded by her mate, on vegetation in streams. Oviposition aggregations are commonly observed in this species, despite their territorial nature during other behaviors. We conducted experiments in the field to test the hypothesis that aggregations are the result of conspecific attraction. In the first experiment, two oviposition sites (sycamore leaves) were provided, one with models of ovipositing pairs, and one without. In the second experiment, one leaf again had ovipositing models, while the other had models of uncoupled males and females in a resting posture. In both experiments, damselfly pairs preferred the site with ovipositing models. In general, they visited the ovipositing models first more often than expected by chance, stayed longer there, were more likely to oviposit there, and laid a greater total number of eggs there. These results support the hypothesis that conspecific attraction is responsible for ovipositing aggregations in A. moesta and that posture is an important cue for attraction. Using conspecific cues could be a beneficial strategy to save in search costs while taking advantage of the presence of ovipositing conspecifics to dilute the effects of harassment and predation.     

Responses of leaf miners to atypical leaf production patterns

Abstract. 1. Larvae of two bivoltine species of leaf-mining Lepidop-tera, Acrocercops sp. and Neurobathra strigifinitella (Clem.), restrict feeding to young, second-flush leaves of their host trees in north Florida.
2. During 1980 and 1981, densities of both species varied greatly among thirty small water oaks ( Quercus nigra ), as did timing and extent of secondary leaf production.
3. In both years leaf-miner density at the end of the first generation (mid-August) was positively correlated with secondary leaf production.
4. Five trees abscised their leaves and reflushed new ones at atypical times of the growing season. When refoliation coincided with emergence of ovipositing adults, Acrocercops sp. and N.strigifinitella densities increased dramatically, indicating that both species are at times limited by availability of young leaves.
5. By staggering termination of diapause these leaf miners can exploit a temporally variable resource.     

Behavioral cues associated with oviposition by Trioza eugeniae

Trioza eugeniae oviposited significantly more eggs on Syzygium paniculatum leaves free of eggs compared to leaves with pre-existing eggs in a choice experiment, suggesting that females modify oviposition based on cues associated with the presence of eggs. In separate experiments, females avoided ovipositing on parts of leaves where eggs were present, but readily oviposited on areas of the same leaf without eggs. Epideictic pheromones are apparently not used by this species because females readily oviposited on areas of a leaf from which eggs had previously been removed. Females laid 57% of all their eggs along the margins of normal leaves, but also oviposited on artificial margins produced by cutting the leaves. The preference for natural margins over artificial margins was eliminated when the entire margin was coated with an antitranspirant compound to mask the damaged edge. These studies show that ovipositing psyllids respond both to the presence of eggs and to the suitability of the substrate.     

Strong influence of leaf tie formation and corresponding weak effect of leaf quality on herbivory in eight species of Quercus

1. Leaf shelter construction by herbivorous insects can improve leaf quality, sometimes changing resultant herbivory. In two experiments in a Missouri (USA) deciduous forest we quantified the impact of leaf tie construction and changes to leaf quality on subsequent leaf damage.
2. First, using eight Quercus species, we compared damage to single leaves versus experimental leaf ties that had been stocked with either Pseudotelphusa quercinigracella (Gelechiidae) or Psilocorsis cryptolechiella (Depressariidae) to determine how initial leaf quality (total phenolics) influenced damage caused by shelter inhabitants. Skeletonization by leaf tying caterpillars and leaf edge chewing by free feeding species were 12.2× and 1.3× greater on tied than on non-tied leaves, respectively. July and September leaf phenolic content had a slight positive effect on the probability of skeletonization, none on the probability of edge damage, and a weakly positive or negative effect on the intensity of skeletonization and edge damage, depending on leaf position.
3. Second, we created experimental leaf ties, protected from herbivores, on the same Quercus species to determine whether tie formation changes leaf quality (total phenolics, nitrogen, water, toughness). Tie formation decreased phenolics, but this change was predicted to add only 0.8% leaf area loss.
4. Synthesis. Herbivory increased dramatically when leaves were in ties, with the effect mostly due to the tie itself rather than a change in leaf quality. We predict that the advantages of building and using leaf ties in this system are more likely to be escape from natural enemies and changes in abiotic factors.

     

Myrmecophily in Hesperiidae. The case of Vettius tertianus in ant gardens

The larvae of the hesperiid butterfly Vettius tertianus develop by eating the leaves of Aechmea mertensii, a bromeliad epiphyte restricted to ant gardens. The relationships between ants and V. tertianus larvae highlight the preferential association of the caterpillars with Pachycondyla goeldii (Ponerinae), an ant-garden initiator. The oviposition strategy of V. tertianus may thus imply the identification of the inhabiting ant species and not only the identification of the host plant. The caterpillars neither provide secretions to the ants, nor possess defensive devices (i.e. hairs or appendices) against ants. Their activity rhythm does not isolate them from foraging workers of P. goeldii and their shelters are also attainable by the ants. Moreover, as the cuticular lipid profiles of V. tertianus larvae are clearly different from those of the ants and also from the leaf-surface of A. mertensii, acceptance is not due to mimicry between larvae and plants or ants. However, the caterpillars deposit, on the leaf they eat, silk containing a mixture of substances very similar to those found on their own cuticle. No interaction with ants was recorded during observations, even though the ant gardens were patrolled by numerous P. goeldii individuals during their activity period. But when confronted with the caterpillar, none of the tested ant species reacted aggressively. These results suggest the existence of compounds, other than cuticular lipids, responsible for the absence of aggressiveness in the ants. The case of V. tertianus is relatively new as myrmecophily within Hesperiidae has been described only once. Moreover, it preferentially involves a member of the Ponerinae, a subfamily in which interactions with other arthropods are exceptional.     

Fitness costs and benefits of shelter building and leaf trenching behaviour in a pyralid caterpillar

1. Shelter building and petiole trenching in the Lepidoptera is a behaviour that mediates ecological pressures including those exerted by both food plants and natural enemies. 2. Fitness costs and benefits of trenching and shelter‐building behaviour related to predation and larval performance were investigated in a pyralid species that inhabits and feeds on leaf shelters. 3. Assays comparing the performance of caterpillars feeding on trenched versus non‐trenched foliage and fresh versus dry leaves were conducted. Whereas pupal weight was positively affected by petiole trenching, larval development was delayed when caterpillars fed on dry leaves. 4. A field experiment comparing predation on caterpillars inside and outside shelters demonstrated that predation was significantly higher for exposed caterpillars. 5. No physiological costs associated with shelter building were found given that caterpillars performed equally regardless of the number of shelters they built. 6. The effect sizes of top‐down and bottom‐up forces on pupal weight, development time, and predation risk indicated that the major effect of shelters is through the reduction of predation risk. The integration of experiments and natural history observations showed that fitness benefits provided by shelters change across ontogeny.     

To mate or not to mate,and subsequent host search by a haplodiploid female parasitoid wasp

Mated females of haplodiploid species can vary the sex ratio of their offspring, but virgin or sperm‐depleted females can produce only males. Depending on the costs and benefits, the theory of constrained sex allocation states that female haplodiploids may vary in their propensity to mate, with important implications for the populations’ sex ratio. Unmated female parasitoid wasps Alabagrus texanus (Braconidae) have been observed to reject matings with males, even under highly confined spatial conditions. We performed field trials to determine whether unmated female A. texanus would mate. We then compared the preferences of the resulting unmated (constrained) and mated (unconstrained) female wasps for shelters constructed and occupied by their hosts, fern moth caterpillars Herpetogramma theseusalis (Crambidae) on fern fronds. We presented the wasps with pairs of shelters collected from the field that differed in size, as well as freshness, fern species, and presence or absence of caterpillars. Unconstrained females searched small shelters more frequently than did constrained females and tended to favor senesced (old) shelters over fresher ones. They did not differ in choice between shelters on marsh and sensitive ferns or between shelters containing caterpillars and empty shelters. The preference for small shelters by the unconstrained wasps may enhance their rate of contacting favorable hosts, but the foraging regime of the constrained females should expose them to caterpillars at sites infrequently searched by the unconstrained females.     

Myrmecophilous butterflies utilise ant–treehopper associations as visual cues for oviposition

1. Selection of a safe oviposition site is important for herbivorous insects whose immature stages have limited mobility. Female herbivores rely on environmental cues for this choice, and presence of natural enemies or mutualistic partners may be important in this process. 2. Some butterflies have mutualistic interactions with ants (myrmecophily), in which caterpillars offer a nutritional liquid and gain protection against natural enemies. Participants in butterfly–ant mutualisms may utilise signals to initiate interactions, but the use of visual cues by ovipositing myrmecophilous butterflies remains uncertain. 3. Larvae of facultatively myrmecophilous Parrhasius polibetes (Lycaenidae) feed on Schefflera vinosa, and females prefer to oviposit near aggregations of the ant‐tended treehopper Guayaquila xiphias, where caterpillars survive better due to increased ant attendance. Given the conspicuousness of ant–treehopper associations, it was investigated whether butterflies use them as visual cues for oviposition and, if so, which participants of the association are used as cues: ants, treehoppers, or both. 4. Experiments using dried insects on paired branches revealed that females visually recognise ants and ant–treehopper associations, using them for egg‐laying decisions. However, presence of a treehopper aggregation alone had no effect on oviposition choices. 5. This is a first insight into the importance of visual discrimination for ovipositing myrmecophilous butterflies. The results show that facultative mutualisms can be important enough to promote a behavioural adaptation (visual detection of ants) reinforcing the interaction. Our research highlights the importance of the behavioural interface within complex multispecies systems.     

Effects of leaf nitrogen content on oviposition site selection, offspring performance, and intraspecific interactions in an omnivorous bug

Abstract.  1. Oviposition site preference and its relation to offspring performance have received much attention in studies of herbivorous insects. Although this relationship is of great ecological significance, its presence in predacious and omnivorous insects has hardly been explored. When selecting an oviposition site, omnivores are expected to respond to both prey availability and, even more strongly, to plant traits that affect both females and their offspring.
2. In this study, females of Orius albidipennis (Heteroptera: Anthocoridae) showed a strong preference for oviposition at the vein origin site of cotton leaves. It appears that this site is a limited resource for ovipositing females, because they defend it against conspecific intruders. This defensive behaviour was significantly more pronounced on nitrogen-rich than nitrogen-poor plants.
3. The females' defensive behaviour on nitrogen-rich leaves corresponds with offspring performance; the nymphs developed faster and enjoyed higher survival on nitrogen-rich than on nitrogen-poor leaves. At the between-plant level, oviposition preference was not significantly correlated with offspring performance, and egg hatching rate did not differ significantly between nitrogen treatments.
4. Oviposition site selection by this omnivorous bug appears, however, to be correlated positively with offspring performance at the within-leaf level. This is supported by the significantly higher hatching success of eggs deposited at the preferred vein origin site as compared with those deposited on other parts of the leaf.     

Preference and performance are correlated in the spittlebug Aphrophora pectoralis on four species of willow

Abstract 1. There was a positive correlation between oviposition and feeding preferences and offspring performance in the spittlebug Aphrophora pectoralis Matsumura (Homoptera: Cercopoidea, Aphrophoridae) on four species of willow Salix sp. (Salicaceae) growing near Sapporo, Japan. Spittlebugs preferred rapidly growing shoots where performance was highest.
2. When the effects of shoot length were removed, egg densities on willow species were associated with offspring performance on three of four species. Egg densities and survival rates were low on Salix integra and Salix miyabeana . Survival rates were high on Salix sachalinensis , which had high egg densities, and Salix hultenii , which had low egg densities.
3. Aphrophora pectoralis formed mating aggregations almost exclusively on S. sachalinensis but then dispersed to other willow species to oviposit.
4. Nymphs dispersed from the oviposition site to feed on nearby shoots within the same plant but they did not disperse to other willow plants. Nymphs had the same preference for rapidly growing shoots as ovipositing females, so they were able to refine the maternal choice by moving to larger shoots near the shoot on which they had eclosed.
5. The spittlebugs were highly aggregated at all life stages so that even at high densities only a small proportion of the most vigorously growing shoots was utilised.     

Pre-oviposition mate-guarding and mating behaviour of Argia vivida (Odonata: Coenagrionidae)

Abstract. 1. At Halcyon Hotsprings, British Columbia, Canada, male and female Argia vivida Hagen encountered to mate in two different ways.
2. In the morning (before 12.30 hours solar time), males basked at sunspots in the forest and darted out at passing females, attempting to take them in tandem (the first method of encounter).
3. If a male was successful, the pair engaged in a 31.3±4.8 min copulation followed by an hour of tandem flight before beginning oviposition.
4. As the day progressed, unmated males moved slowly toward the water and arrived at the water at about the same time as the earliest ovipositing pairs (1131±27.5 min solar time).
5. Males retained their grasp on their mates during oviposition (contact-guarding) but since some tandems separated during oviposition, non-tandem males at the water could capture recently released, gravid females (the second method of encounter).
6. The new pairs performed a brief copulation (10.2±3.38 min) and began ovipositing immediately thereafter.
7. Some females that avoided recapture attempted to oviposit unguarded.
8. We believe the long duration of morning copulations and period of tandem constitute a male strategy, which we call 'pre-oviposition guarding', to guard females until it is warm enough at the oviposition site for the females to begin ovipositing.
9. Separation of tandems during oviposition may be initiated by either member of the pair and we suggest that one benefit to a female of leaving a guarding mate is increased efficiency of oviposition when the intensity of male harassment is low.
10. The mating system of A. vivida thus comprises a series of complementary male and female mating behaviours.     

Leaf shelter-building caterpillars harness forces generated by axial retraction of stretched and wetted silk

Leaf shelter-building caterpillars generate most of the force required to pull leaf surfaces together by stretching silk strands while spinning. Axially retractive forces produced by columns of stretched strands enabled caterpillars in our study to generate forces as great as 0.3 Newtons (i.e., a 30-g force). We found that caterpillar silk also contracts instantly when wetted, producing an additional, though smaller, axially retractive force. Contraction ratios (final length/ original length) of the wetted silk of 19 species ranged from 0.21 to 0.93 and were smallest among species that use their silk to make leaf shelters. Our study, the first to identify the specific sources of the energy harnessed by caterpillars to tie, roll, or fold leaves, indicates that silk properties and caterpillar behavior have coevolved to facilitate the leaf shelter-building process.     

Positive and negative effects of leaf shelters on herbivorous insects: linking multiple herbivore species on a willow

We experimentally examined the effects on other herbivorous insects of leaf shelters constructed by lepidopteran larvae on a willow, Salix miyabeana. Several insect species occupied the vacant leaf shelters. Our experiment using artificial leaf shelters showed that the number of aphids increased with the number of artificial leaf shelters on a shoot, as did the numbers of three ant species ( Camponotus japonicus, Lasius hayashi, and Myrmica jessensis) that entered leaf shelters to collect aphid honeydew. To determine the ant-mediated effect of leaf shelters on herbivorous insects that do not use leaf shelters, we transferred newly hatched larvae of a common leaf beetle, Plagiodera versicolora, to the leaves of shoots with and without artificial leaf shelters. One day after the transfer, larval survival rate was significantly lower on shoots with shelters than on those without shelters, and shoots with shelters had significantly more ants than did shoots without shelters. Our field experiments demonstrated clearly that shelter-making lepidopteran larvae increased the abundance of both aphids and ants and decreased the survival rate of leaf beetle larvae, probably because the larvae were removed by ants that were attracted to the leaf shelters by the aphid colonies.     

Species composition and life histories of shelter-building caterpillars on Salix miyabeana

We studied the species composition and life history patterns of shelter‐building microlepidoptera on the willow Salix miyabeana in Hokkaido, northern Japan. We identified 23 microlepidopteran species across seven families that constructed leaf shelters. Species in Tortricidae and Pyralidae comprised approximately 90% of the total number of sampled shelter‐building microlepidoptera that reached adult eclosion in the laboratory. Seasonal changes in the density of leaf shelters showed two peaks: early June and mid‐August. In June, caterpillars of Gypsonoma bifasciata, Gypsonoma ephoropa, Acleris issikii and Saliciphage acharis were the principal shelter builders, while in August shelters were constructed primarily by caterpillars of Nephopterix adelphella, A. issikii and S. acharis. Approximately 90% of leaf shelters were constructed on the top portions of shoots, suggesting that most shelter‐building caterpillars prefer to build leaf shelters here.     

Colonisation of pitcher plant leaves at several spatial scales

Abstract.  1. The effect of meso-scale (zone within bog and local plant density) and fine-scale (leaf length and resource availability) factors on the colonisation of pitcher plant leaves by arthropods was examined in an eastern Canadian bog.
2. In spring, the abundances of three arthropods, the mosquito Wyeomyia smithii , the midge Metriocnemus knabi , and the mite Sarraceniopus gibsoni , were determined for plots with low, moderate, and high densities of pitcher plants. All overwintering inhabitants were then removed from the plots. Newly opening leaves were colonised from outside the plots, and arthropod abundances were assessed again in autumn.
3. Pitcher plant fauna varied in their response to the meso-scale factors. In autumn (soon after colonisation), midges were more abundant in areas with high densities of pitcher plants. The relationship between mosquito abundance and plant density, and the variation in abundance among zones within the bog in the spring, were probably due to overwintering mortality.
4. All taxa responded to the fine-scale factors, leaf length, and capture rate, in the autumn, but the strength of the responses frequently depended on a meso-scale factor (plant density), in which responses were usually strongest where plants were sparse. Thus, the interaction between meso- and fine-scale processes needs to be considered when interpreting patterns of species abundance within arthropod assemblages in pitcher plant leaves.     

Cucurbitane glucosides from Momordica charantia leaves as oviposition deterrents to the leafminer, Liriomyza trifolii

The American serpentine leaf mining fly, Liriomyza trifolii, whose larva feeds on more than 120 plant species is well characterized by its high degree of polyphagy. Observations on the oviposition behavior by L. trifolii demonstrated that among cucurbitaceous plants, Momordica charantia is rarely attacked by L. trifolii. The methanol extract of M. charantia leaves strongly deterred the females from ovipositing on kidney bean leaves treated at a concentration of 1 g leaf equivalent extract/ml. Analysis of the polar fraction of the methanol extract of M. charantia leaves resulted in the isolation of a novel cucurbitane glucoside, 7-O-beta-D-glucopyranosyl-3,23-dihydroxycucurbita-5,24-dien-19-al, named momordicine IV, along with another known compound, momordicine II. Momordicine II and IV deterred oviposition by L. trifolii significantly when bioassays were carried out on kidney bean leaves treated at 75.6 and 20.3 microg/cm2 leaf surface, respectively. There was no synergistic effect on oviposition deterrent when the two compounds were combined in their natural abundance.