The Effect of Social Norms on Residential Insecticide Use.

Insecticide products are widely used in homes around the world, despite concerns about their adverse health effects. Variations in insecticide use levels can stem not only from differences in environmental conditions, but also from societal factors. This study investigates the impact of religiosity on insecticide use in Jewish households, hypothesizing that religious families might use more insecticides because insects are considered taboo in Judaism. Data from interviews with 70 families, examining their insecticide use, exposure to pests, aversion to cockroaches, and other predisposing factors, revealed that despite similar levels of pest exposure, religious families reported higher insecticide use and greater aversion to cockroaches. Multiple linear regression analysis identified religiosity as the primary predictor of insecticide use, followed by pest exposure levels. The elevated insecticide use among religious Jewish families may stem from several factors, with the Jewish categorization of insects as "impure animals" that should be strictly avoided likely playing a crucial role in promoting insecticide use. Understanding how attitudes toward insects influence insecticide use across different societies is crucial for health and environmental authorities to develop novel insecticide-reduction initiatives that will be tailored to the unique social characteristics of various communities.

Effects of Natural Habitat and Season on Cursorial Spider Assemblages in Mediterranean Vineyards.

Natural habitats adjacent to vineyards are presumed to have a positive effect on the diversity of natural enemies within the vineyards. However, these habitats differ in vegetation structure and seasonal phenology and in turn could affect the species composition of natural enemies. Here, we compared the species richness and diversity and the composition of spider assemblages in several locations within three commercial vineyards and the nearby natural habitats in a Mediterranean landscape in northern Israel. We sampled spiders by means of pitfall traps in early and in late summer. Both the time in the season and the habitat (natural versus vineyard) affected spider species richness and diversity. More species were found in early summer (47) than in late summer (33), and more occurred in the natural habitat (34 species) than in the vineyards (27-31 species). Fifteen species were found exclusively in the natural habitat, and only 11 species were shared by the vineyards and natural habitat, four of which were the most abundant and geographically widely distributed species in the samples. In late summer, spider diversity in the natural habitat was higher than within the vineyards: the spider assemblages in the vineyards became dominated by a few species late in the crop season, while those of the natural habitat remained stable. Overall, the natural habitat differed in assemblage composition from all within-vineyard locations, while the three locations within the vineyard did not differ significantly in assemblage composition. Season (early vs. late summer), however, significantly affected the spider assemblage composition. This study documents the large diversity of spiders in a local Mediterranean vineyard agroecosystem. Over 60% of the known spider families in the region occurred in our samples, highlighting the importance of this agroecosystem for spider diversity and the potential for conservation biocontrol, where natural habitats may be a source of natural enemies for nearby vineyards.

The Destructive Effects of Recreational Off-Highway Vehicles on Farmer Well-Being: Mental Health Consequences Outweigh Economic Losses.

In many countries, the use of recreational off-highway vehicles (ROVs) occasionally spills over into agricultural lands. The conflict between ROV users and farmers is escalating due to the growing popularity of ROVs. Determined action of authorities for mitigating the phenomenon may necessitate an understanding of the nature and extent of the actual damage caused by ROVs. However, it is currently unknown how ROVs harm agriculture and what is their main deleterious effect on farmers. We tested our hypothesis that economic costs are the leading reason for farmer distress using in-depth interviews with 46 Israeli farmers that are affected by ROVs. We found that contrary to our hypothesis, economic costs were low and negligible, despite high levels of anger, distress, or hopelessness expressed by almost all farmers. The main reason for outrage and frustration was the emotional impact of ROV activity on the farmers. Therefore, measuring the effects of ROVs on agriculture in terms of economic losses will probably be ineffective in convincing policymakers to act against the reckless use of ROVs in agricultural lands. On the other hand, conveying the emotional implications for the farmers can potentially promote change if accompanied by explanations on the importance of caring for the mental health and well-being of a sector that already suffers from levels of stress and mental health problems that are among the highest of any other industry in the world.

Does Insect Aversion Lead to Increased Household Pesticide Use?

In many human societies, domestic insect pests often evoke feelings of disgust, fear and aversion. These common feelings may translate to increased use of household pesticides. No study has ever explored this possibility and consequently, efforts to mitigate public exposure to domestic pesticides typically focus on addressing knowledge gaps. We tested the hypothesis that negative emotions toward insects may motivate people to use pesticides, by interviewing 70 participants and assessing their insect aversion levels using a computerized test. Contrary to our hypothesis, we found no effect of insect aversion on pesticide use. However, we did find that personal attributes and preferences such as wishing to avoid exposure to toxic chemicals, being vegetarian and taking frequent nature walks reduced pesticide use, in addition to low infestation levels and physical attributes of the housing unit. We emphasize the importance of conducting future studies in various societies, where insect aversion and other factors may have different effects on household pesticide use. Such studies may provide culture-specific insights that could foster the development of next-generation urban IPM (Integrated Pest Management) public education programs, which will address not only knowledge gaps, but also emotional aspects and personal attributes that lead to unnecessary or excessive use of household pesticides.

Standing on the shoulders of giants: young aphids piggyback on adults when searching for a host plant.

BACKGROUND: Upon the detection of imminent peril, pea aphids (Acyrthosiphon pisum) often drop off their host plant. Dropping in response to insect enemies is intermittent in nature, but when a mammalian herbivore feeds on their host plant, a large mixed-age group of aphids usually drops off the plant at once. Aphids that reach the ground are confronted with new, hostile environmental conditions and must therefore quickly walk toward a suitable host plant. The longer it takes an aphid to reach a host plant, the more it is exposed to the risks of starvation, desiccation and predation. RESULTS: We found that young nymphs, which have limited mobility and high mortality on the ground, quickly climb on conspecific (not necessarily parental) adults and cling to them before the latter start walking in search of a plant. This "riding" behavior is likely to be adaptive for the nymphs, for it shortens their journey and the time they spend off a host plant. Adults however, seem to be irritated by the riding nymphs, as they often actively try to remove them. CONCLUSIONS: After dropping from the host plant, young aphid nymphs travel at least part of the way back to a plant on the backs of adults. For the riding behavior to take place, nymphs need to successfully find adults and withstand removal attempts.

How goats avoid ingesting noxious insects while feeding.

As mammalian herbivores feed, they often encounter noxious insects on plants. It is unknown how they handle such insects. We experimentally examined the behavioural responses of goats to the noxious spring-webworm (Ocnogyna loewii), and manipulated their sensory perception to reveal the process of insect detection. Goats did not avoid plants with webworms, demonstrating a remarkable ability to sort them apart from the plant (98% of webworms survived). Initial detection of webworms involved tactile stimulation, done by repeatedly touching the leaves with the muzzle. This enabled them to pick webworm-free leaves. If the goats picked up leaves with a webworm, they shook or discarded the leaf. They spat out webworms that entered their mouths, after detecting them by touch and taste. By using their keen senses and efficient behaviours, goats are able to feed while accurately excluding insects. These findings highlight the importance of direct interactions between mammalian herbivores and insects.

Direct consumptive interactions between mammalian herbivores and plant-dwelling invertebrates: prevalence, significance, and prospectus.

Mammalian herbivores induce changes in the chemical composition, phenology, distribution, and abundance of the plants they feed on. Consequently, invertebrate herbivores (predominantly insects) that depend on those plants, and the predators and parasitoids that are associated with them, may be affected. This plant-mediated indirect interaction between mammals and invertebrates has been extensively studied, but mammalian herbivores may also directly affect plant-dwelling invertebrates (PDI) by incidentally ingesting them while feeding. The ubiquity and small size of PDI render them highly susceptible to incidental ingestion, but as common as this interaction may intuitively seem, very little is known about its prevalence and ecological consequences. Nevertheless, cases of incidental ingestion of PDI and associated adaptations for avoiding it that have been sporadically documented in several invertebrate groups and life stages allow us to carefully extrapolate and conclude that it should be common in nature. Incidental ingestion may, therefore, bear significant consequences for PDI, but it may also affect the mammalian herbivores and the shared plants. Future research on incidental ingestion of PDI would have to overcome several technical difficulties to gain better insight into this understudied ecological interaction.

Mechanical defenses of plant extrafloral nectaries against herbivory.

Extrafloral nectaries play an important role in plant defense against herbivores by providing nectar rewards that attract ants and other carnivorous insects. However, extrafloral nectaries can themselves be targets of herbivory, in addition to being exploited by nectar-robbing insects that do not provide defensive services. We recently found that the extrafloral nectaries of Vicia faba plants, as well as immediately adjacent tissues, exhibit high concentrations of chemical toxins, apparently as a defense against herbivory. Here we report that the nectary tissues of this plant also exhibit high levels of structural stiffness compared to surrounding tissues, likely due to cell wall lignification and the concentration of calcium oxalate crystals in nectary tissues, which may provide an additional deterrent to herbivore feeding on nectary tissues.

Targeted predation of extrafloral nectaries by insects despite localized chemical defences.

Extrafloral (EF) nectaries recruit carnivorous arthropods that protect plants from herbivory, but they can also be exploited by nectar thieves. We studied the opportunistic, targeted predation (and destruction) of EF nectaries by insects, and the localized chemical defences that plants presumably use to minimize this effect. In field and laboratory experiments, we identified insects that were possibly responsible for EF nectary predation in Vicia faba (fava bean) and determined the extent and accuracy of the feeding damage done to the EF nectaries by these insects. We also performed biochemical analyses of plant tissue samples in order to detect microscale distribution patterns of chemical defences in the area of the EF nectary. We observed selective, targeted feeding on EF nectaries by several insect species, including some that are otherwise not primarily herbivorous. Biochemical analyses revealed high concentrations of l-3,4-dihydroxyphenylalanine, a non-protein amino acid that is toxic to insects, near and within the EF nectaries. These results suggest that plants allocate defences to the protection of EF nectaries from predation, consistent with expectations of optimal defence theory, and that this may not be entirely effective, as insects limit their exposure to these defences by consuming only the secreting tissue of the nectary.

Handheld lasers allow efficient detection of fluorescent marked organisms in the field.

Marking organisms with fluorescent dyes and powders is a common technique used in ecological field studies that monitor movement of organisms to examine life history traits, behaviors, and population dynamics. External fluorescent marking is relatively inexpensive and can be readily employed to quickly mark large numbers of individuals; however, the ability to detect marked organisms in the field at night has been hampered by the limited detection distances provided by portable fluorescent ultraviolet lamps. In recent years, significant advances in LED lamp and laser technology have led to development of powerful, low-cost ultraviolet light sources. In this study, we evaluate the potential of these new technologies to improve detection of fluorescent-marked organisms in the field and to create new possibilities for tracking marked organisms in visually challenging environments such as tree canopies and aquatic habitats. Using handheld lasers, we document a method that provides a fivefold increase in detection distance over previously available technologies. This method allows easy scouting of tree canopies (from the ground), as well as shallow aquatic systems. This novel detection method for fluorescent-marked organisms thus promises to significantly enhance the use of fluorescent marking as a non-destructive technique for tracking organisms in natural environments, facilitating field studies that aim to document otherwise inaccessible aspects of the movement, behavior, and population dynamics of study organisms, including species with significant economic impacts or relevance for ecology and human health.

Herbivore-induced plant volatiles in natural and agricultural ecosystems: open questions and future prospects.

Herbivore-induced plant volatiles (HIPV) have been shown to convey ecologically relevant information to other organisms, including carnivorous and herbivorous arthropods and neighboring plants. However, many questions about the evolutionary and ecological functions of HIPV remain unanswered. In particular, a current lack of information about the ways in which environmental factors-including habitat structure and atmospheric conditions-influence HIPV mediated interactions in real-world settings limits our ability to anticipate the ways in which HIPV-mediated ecological interactions may be altered or disrupted by anthropogenic environmental change, including atmospheric pollution and climate change. Understanding these influences thus has significant implications for the sustainable management of natural and agricultural ecosystems and should be a priority for future research.

Young aphids avoid erroneous dropping when evading mammalian herbivores by combining input from two sensory modalities.

Mammalian herbivores may incidentally ingest plant-dwelling insects while foraging. Adult pea aphids (Acyrthosiphon pisum) avoid this danger by dropping off their host plant after sensing the herbivore's warm and humid breath and the vibrations it causes while feeding. Aphid nymphs may also drop (to escape insect enemies), but because of their slow movement, have a lower chance of finding a new plant. We compared dropping rates of first-instar nymphs with those of adults, after exposing pea aphids to different combinations of simulated mammalian breath and vibrations. We hypothesized that nymphs would compensate for the greater risk they face on the ground by interpreting more conservatively the mammalian herbivore cues they perceive. Most adults dropped in response to breath alone, but nymphs rarely did so. Breath stimulus accompanied by one concurrent vibrational stimulus, caused a minor rise in adult dropping rates. Adding a second vibration during breath had no additional effect on adults. The nymphs, however, relied on a combination of the two types of stimuli, with a threefold increase in dropping rates when the breath was accompanied by one vibration, and a further doubling of dropping rates when the second vibration was added. The age-specificity of the aphids' herbivore detection mechanism is probably an adaptation to the different cost of dropping for the different age groups. Relying on a combination of stimuli from two sensory modalities enables the vulnerable nymphs to avoid costly mistakes. Our findings emphasize the importance of the direct trophic effect of mammalian herbivory for plant-dwelling insects.

Avoiding incidental predation by mammalian herbivores: accurate detection and efficient response in aphids.

Mammalian herbivores eat plants that may also provide food and shelter for insects. The direct trophic effect of the browsing and grazing of mammalian herbivory on insects, which is probably prevalent in terrestrial ecosystems, has been mostly neglected by ecologists. We examined how the aphid Uroleucon sonchi L. deals with the danger of incidental predation by mammalian herbivores. We found that most (76%) of the aphids in a colony survive the ingestion of the plant by a feeding herbivore. They do so by sensing the combination of heat and humidity in the herbivore's breath and immediately dropping off the plant in large numbers. Their ability to sense the herbivore's breath or their tendency to drop off the plant weakens as ambient temperature rises. This could indicate a limitation of the aphids' sensory system or an adaptation that enables them to avoid the hostile conditions on a hot ground. Once on the ground, U. sonchi is highly mobile and capable of locating a new host plant by advancing in a pattern that differs significantly from random movement. The accurate and efficient defense mechanism of U. sonchi emphasizes the significance of incidental predation as a danger to plant-dwelling invertebrates.

Mammalian herbivore breath alerts aphids to flee host plant.

Mammalian herbivores profoundly influence plant-dwelling insects [1]. Most studies have focused on the indirect effect of herbivory on insect populations via damage to the host plant [2,3]. Many insects, however, are in danger of being inadvertently ingested during herbivore feeding. Here, we report that pea aphids (Acyrthosiphon pisum) are able to sense the elevated heat and humidity of the breath of an approaching herbivore and thus salvage most of the colony by simultaneously dropping off the plant in large numbers immediately before the plant is eaten. Dropping entails the risk of losing the host plant and becoming desiccated or preyed upon on the ground [4,5], yet pea aphids may sporadically drop when threatened by insect enemies [6]. The immediate mass dropping, however, is an adaptation to the potential destructive impact of mammalian herbivory on the entire aphid colony. The combination of heat and humidity serves as a reliable cue to impending mammalian herbivory, enabling the aphids to avoid unnecessary dropping. No defensive behavior against incidental predation by herbivores has ever been demonstrated. The pea aphids' highly adaptive escape behavior uniquely demonstrates the strength of the selective pressure large mammalian herbivores impose on insect herbivores.