Joseph M. Patt

Odor‐based recognition of nectar in cursorial spiders

Carnivorous arthropods are known to rely on non‐prey foods, such as honeydew, pollen, and nectar. Consumption of plant‐based nutrients by spiders also appears to be widespread, especially in cursorial species. This is not surprising, as studies have shown that these spiders’ activity levels, survivorship, and reproduction are increased when their diet includes plant‐based nutrients, especially under conditions of prey scarcity. However, the sensory and behavioral means by which they recognize and locate non‐prey food is unknown. Here we show that immatures of a nectarivorous spider [Hibana futilis Banks (Araneae: Anyphaenidae)] can recognize and remember particular chemical stimuli associated with nectar. Following ingestion of minute amounts of sugar, these spiders exhibited counterturning and other local searching behaviors that increased their chances of finding more nectar. When placed on test arenas, spiders that were naïve with respect to nectar aroma located artificial nectaries composed of diluted honey significantly faster than unscented nectaries composed of 1 m sucrose solution. These results indicate that H. futilis is neurophysiologically and behaviorally adapted for recognizing olfactory stimuli. Interestingly, only spiders that ingested sugar and were engaged in local search responded to nectar aroma, suggesting that stimulation into local search is necessary to prime olfactory responses. We found that H. futilis could be conditioned to associate the presence of nectar with a novel aroma, in this case vanilla, and remember this aroma over the course of several hours. In arenas with vanilla‐scented nectaries, spiders that had previous experience feeding on vanilla‐scented sucrose droplets located the nectaries significantly faster than did vanilla‐naïve spiders. The capacity to remember specific aromas could enhance the spiders’ ability to find nectar, either when moving between different parts of the same plant or among different plant species. The results here indicate that nectarivorous spiders possess the sensory capabilities and programed behaviors necessary for efficient detection, recognition, and location of nectar sources.

Identification of Grape Juice Aroma Volatiles and Attractiveness to the Mexican Fruit Fly (Diptera: Tephritidae)

Abstract Volatiles from a Concord grape juice produced in Mexico were identified, tested for attractiveness, and mixed into an attractive blend. Volatiles were sampled with solid phase microextraction (SPME). Chemicals were analyzed by gas chromatography and identified by mass spectrometry (GC-MS). Identified chemicals were ethanol, ethyl propionate, ethyl butyrate, ethyl 2-methylbutyrate, ethyl decanoate, ethyl dodecanoate, D-limonene, sorbic acid, benzoic acid, methyl anthranilate, and dimethyl anthranilate. Chemicals were tested at 2 concentrations, 1 μg and 100 ng, for attractiveness to Mexican fruit flies (Anastrepha ludens) in laboratory cage-top bioassays. All test chemicals except sorbic acid were attractive to either sugar-fed or sugar-starved flies over both concentrations tested. A nine-component synthetic grape essence mixture was developed that matched the headspace volatiles profile of the grape juice. Attractiveness of the mixture was equal to that of the grape juice in laboratory bioassays. The mixture was 70% as attractive as the juice in traps in field tests. Results demonstrate that most of the attractive principals of the juice were identified.

Characterization of restricted area searching behavior following consumption of prey and non-prey food in a cursorial spider, Hibana futilis.

Cursorial spiders are important predators of crop pests in a variety of agricultural systems. Their survivorship, growth, and fecundity can be enhanced by the consumption of extra‐floral nectar. We recently showed that Hibana futilis (Banks) (Araneae: Anyphaenidae) engages in restricted area search following contact with nectar, is stimulated by nectar aroma, and can learn to recognize novel aroma cues. Studies have shown that H. futilis is also responsive to solvent extracts of the eggs and scales of the corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), one of its primary prey insects in cotton. The arrestment behavior of cursorial spiders following consumption of prey and non‐prey food has not been characterized. In the present study, the responses of spiders were measured following consumption of prey (H. zea eggs) or non‐prey (droplets of dilute honey) food items and compared with individuals tested without food items. The food items were presented to the spiders in test arenas constructed from the top of an inverted glass Petri dish cover. A combination of real time and recorded observations were made via a video camera attached to a computer. The behaviors and movement patterns of individual spiders were analyzed with behavioral tracking software. Significant differences in the behaviors and motion paths of spiders tested in the different treatments were observed. Hibana futilis displayed significantly more dispersal behavior on a blank test arena, than on test arenas supplied with honey droplets or moth eggs. Likewise, spiders tested on the blank arena crawled faster and their motion paths were significantly less tortuous than those of spiders tested in the arenas with honey or moth eggs. Following consumption of both the honey droplets and moth eggs, spiders showed elevated levels of restricted area search and lowered levels of dispersal behavior. The analysis showed that these spiders could crawl rapidly for extended distances. Behaviors such as restricted area search and learned recognition of food‐based stimuli would facilitate efficient location of the food resources needed to maintain their high activity levels.

The Effects of Temperature, Diet, and Other Factors on Development, Survivorship, and Oviposition of Aethina tumida (Coleoptera: Nitidulidae)

ABSTRACT Developmental rate and survivorship of small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae), life stages were measured across different temperatures (21, 25, 28, 32 and 35°C) and diets, which included natural and artificial pollen, honey, and bee pupae. Temperature affected hatch success, time to hatching, and larval growth. Eggs hatched in 61 h at 21°C but in <22 h at 35°C Larvae achieved peak weight in <8 d at 35°C but needed 17 d at 21°C. Diet had comparatively little effect on larval survivorship or maximum weight, although larvae fed only bee pupae had lower survivorship. Access to soil influenced pupation success. Duration of the life stage spent in the soil, during which pupation occurs, was also affected by temperature: adults emerged after 32.7 d at 21°C but after only 14.8 d at 35°C, albeit with high mortality. Minimum temperature for development was estimated at 13.5°C for eggs, and 10.0°C for larvae and pupae. Temperature influenced adult longevity and oviposition: on a honey and pollen diet average adult lifespan was 92.8 d at 24°C but only 11.6 d at 35°C. Beetles lived longer at 28°C or lower but produced the most eggs per female, regardless of diet, at 32°C. Beetle density influenced fecundity: beetles kept at three pairs per vial laid 6.7 times more eggs per female than those kept as single pairs. Overall, beetles fared best at 28–32°C with mortality of all stages highest at 35°C.

Innate and Conditioned Responses to Chemosensory and Visual Cues in Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae), Vector of Huanglongbing Pathogens

Asian citrus psyllid (Diaphorina citri) transmits Huanglongbing, a devastating disease that threatens citrus trees worldwide. A better understanding of the psyllid’s host-plant selection process may lead to the development of more efficient means of monitoring it and predicting its movements. Since behavioral adaptations, such as associative learning, may facilitate recognition of suitable host-plants, we examined whether adult D. citri could be conditioned to visual and chemosensory stimuli from host and non-host-plant sources. Response was measured as the frequency of salivary sheaths, the residue of psyllid probing activity, in a line of emulsified wax on the surface of a test arena. The psyllids displayed both appetitive and aversive conditioning to two different chemosensory stimuli. They could also be conditioned to recognize a blue-colored probing substrate and their response to neutral visual cues was enhanced by chemosensory stimuli. Conditioned psyllids were sensitive to the proportion of chemosensory components present in binary mixtures. Naïve psyllids displayed strong to moderate innate biases to several of the test compounds. While innate responses are probably the psyllid’s primary behavioral mechanism for selecting host-plants, conditioning may enhance its ability to select host-plants during seasonal transitions and dispersal.

Laser system for identification, tracking, and control of flying insects

Flying insects are common vectors for transmission of pathogens and inflict significant harm to humans and agricultural production in many parts of the world. We present proof of principle for an optical system capable of highly specific vector control. This system utilizes a combination of optical sources, detectors, and sophisticated software to search, detect, and identify flying insects in real-time, with the capability of eradication using a lethal laser pulse. We present data on two insect species to show species distinction; Diaphorina citri, a vector of the causal agent of citrus greening disease, and Anopheles stephensi, a malaria vector.

Recognition of Novel Volatile Cues by the Nymphs of the Glassy-winged Sharpshooter, Homalodisca vitripennis (Cicadellidae)

Nymphs of Homalodisca vitripennis are strict xylophages and frequently switch host-plants to obtain a balanced level of nutrients at appropriate tension levels. Associative learning of odors and other semiochemicals may enhance the nymphs’ ability to recognize and locate potential host-plants. We examined whether nymphs could learn to associate a novel olfactory stimulus (vanilla) with a host-plant. Nymphs fed on cowpea plants treated systemically with vanilla extract or on untreated plants. Subsequently, their responses to a pale green target were measured in the presence or absence of vanilla odor. Nymphs were not innately attracted to pale green, and exposure to vanilla odor did not decrease a stereotypical scanning behavior. However, when presented with vanilla odor, significantly more conditioned nymphs selected the target than did control nymphs.

Oviposition Behavior and Survival of Tamarixia radiata (Hymenoptera: Eulophidae), an Ectoparasitoid of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae), on Hosts Exposed to an Entomopathogenic Fungus, Isaria fumosorosea (Hypocreales: Cordycipitaceae), Under Laboratory Conditions.

Abstract Antagonistic interactions between the nymphal parasitoid, Tamarixia radiata Waterston (Hymenoptera: Eulophidae), and the ARSEF 3581 strain of the entomopathogenic fungus, Isaria fumosorosea Wize (Hypocreales: Cordycipitaceae), could disrupt biological control of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). Three interactions were evaluated under laboratory conditions at 25 °C: 1) parasitoid survival if parasitized hosts were exposed to ARSEF 3581 blastospores before or after host mummification; 2) parasitoid survival if mummies containing larva or pupa were exposed to ARSEF 3581 hyphae; 3) parasitoid oviposition on infected hosts with visible or without visible hyphae. Topical application of blastospore formulation onto the dorsal surfaces of live nymphs parasitized with second-instar wasp larva (3 d after parasitism) reduced host mummification by 50% and parasitoid emergence by 85%. However, parasitoid emergence was not affected by topical application of blastospore formulation onto mummies that contained fourth-instar wasp larva (6 d after parasitism). Parasitoid emergence was reduced by 80% if mummies containing fourth-instar wasp larva were covered with blastospore formulation colonized by fungal hyphae. In comparison, parasitoid emergence was not affected if mummies containing wasp pupa (9 d after parasitism) were covered with formulation colonized by fungal hyphae. Female parasitoids oviposited on infected hosts without visible hyphae but not on infected hosts with visible hyphae. Our findings suggest that I. fumosorosea could detrimentally affect T. radiata, if both natural enemies are simultaneously deployed for biological control of D. citri. However, temporal separation of the fungus and parasitoid could reduce antagonism and enhance control of D. citri.

Intraspecific Competition Effects on Aethina tumida (Coleoptera: Nitidulidae)

ABSTRACT Two kinds of experiments were conducted with Aethina tumida Murray larvae over four temperatures: “consumption” experiments, in which larvae and diet were weighed to determine food consumption rates under conditions of unlimited food and few conspecifics; and “competition” experiments, in which varying numbers of larvae were presented with the same amount of honey and pollen diet, and larval weight at final instar was used to determine competition effects. In consumption experiments temperature, diet and their interaction all had significant effects on the ratio of larval weight to the weight of food consumed, which was higher at 24°C than at any other temperature. In competition experiments, three relationships were examined and modeled: that between the number of larvae per experimental unit and the average weight of those larvae; that between average larval and adult weights; and that between average adult weight and survivorship to adult (emergence rate). An exponential decay function was fit to the relationship between number of larvae per experimental unit and their average weight. Average adult weight was linearly correlated with larval weight. Likewise, emergence rates for adults <11.6 mg in weight were linearly correlated with adult weights, but no significant relationship was observed for heavier adults. Using these relationships, the reproductive potential for A. tumida were estimated for a frame of honey and pollen. Information on resource acquisition by A. tumida will be useful in evaluating the impact of different factors on beetle population dynamics, such as bee hygienic behavior or control strategies used by the beekeeper.

Searching Responses of a Hunting Spider to Cues Associated with Lepidopteran Eggs

Cheiracanthium inclusum (Hentz), a hunting spider, feeds on eggs of Helicoverpa zea (Boddie) and other moths. This study investigated whether C. inclusum can use chemical compounds present in H. zea scales and egg residues as kairomones to find these non-motile prey items. In a series of no- choice tests, spiders were presented with a piece of florist paper containing scales alone, scales + egg residues, or untreated controls. Next, spiders were presented with solvent extracts of either scales or eggs. Polar and non-polar solvents were used in the extractions. Contact with scales alone, scales + egg residues, and non-polar solvent extracts of both scales and eggs resulted in retention and/or induction of local searching behavior. Extracts made with polar solvents induced no apparent response, indicating that the chemostimulatory compounds are lipophilic. These results show that C. inclusum responds to kairomones left by ovipositing H. zea and use these chemical cues to detect and locate H. zea eggs.