René Arzuffi

Antennal Sensilla of Toxotrypana curvicauda (Diptera: Tephritidae)

Abstract Antennal morphology and funicular sensilla of male and female papaya fruit fly, Toxotrypana curvicauda Gerstaecker, were studied with light microscopy and scanning electron microscopy. Antennae were 3-segmented, consisting of a scape, a pedicel, a flagellum or funiculus that bears the arista. Antennal segments of males showed a trend toward slightly greater dimensions than those of females, but the differences were not significant. Numerous microtrichia as well as trichoid, basiconic, clavate, and styloconic sensilla were observed on the funiculus, and the sensillar characteristics were similar to those reported for other tephritid species. Males and females did not differ in total number or type of sensilla found on the funiculus, but trichoid and clavate sensilla were significantly larger in females. This difference may be related to female chemoreception of male-emitted sex pheromone and of host plant volatiles.

Sensory Organs in the Antennae of Phyllophaga obsoleta (Coleoptera: Melolonthidae)

Abstract The antennal flagellum of the melolontid beetle Phyllophaga obsoleta Blanchard consists of three terminal plates of lamellae: proximal, middle, and distal. Six types of sensilla were identified on the internal and external surfaces of lamellae from both sexes: placodea (PLAS), basiconica (BAS), coeloconica (COS), auricilica (AUS), chaetica (CHS), and trichodea (TRS). The first four types have been considered as chemoreceptor sensilla and the last two as mechanoreceptor sensilla. The sensilla from the internal and external surfaces of each of three lamellae present in the antennal club from both sexes were mapped by scanning electron microscopy. PLAS were abundant and followed a uniform pattern of distribution on both internal and external surfaces of lamellae from both sexes. Males antennae present a higher number of PLAS in comparison with females antennae. BAS are more abundant in males than in females and follow a more aggregated distribution than PLAS. AUS were included within the BAS group. COS are scarce and only observed on the internal surfaces of all lamellae. TRS and CHS are only present on the periphery of the lamellae. Most sensillar types identified were more abundant in males than in females. The higher number of PLAS observed in males lamellae compared with females lamellae suggests that these sensilla may be involved in sex pheromone reception.

Food aversion learning induced by lithium chloride in the crayfish Procambarus clarkii.

The ability of the crayfish Procambarus clarkii to develop a food aversion learning was examined. For this purpose, in crayfishes fed with trout, a novel food (chicken) was associated in a single trial with a well-known toxic substance, lithium chloride (LiCl), and food intake was recorded for 10 days afterward using a two-choice protocol. All during the experimental period, a significant effect of treatment was observed that accounted for the lower chicken intake in the LiCl-treated group, compared with the control groups (NaCl-treated group and puncture group). In contrast, LiCl-treated animals had an increased trout intake during the entire period. In addition, it was observed that total food intake was similar among the three groups. These results indicate that the crayfish may develop a food aversion learning when illness is induced by LiCl after the animal accepts and eats a novel food.

Mating Behavior of Cnephasia jactatana (Lepidoptera: Tortricidae), an Important Pest of Kiwifruit

ABSTRACT Understanding mating behavioral sequence helps us identify the mechanisms of mate assessment and choice, and better evaluate behavior-based pest control strategies. Here we describe the mating behavior of Cnephasia jactatana Walker whose females release a sex pheromone, and determine the effect of male mating status on reproductive success. The mating sequence starts when males approach females and display courtship behavior with antennation and fanning wings. Both males and females may end a mating attempt at any stage of the sequence. Both sexes assess their mates from the initial contact to copulation. Females appear to be choosier at the early and mid-stages than at the late stage of the sequence. Virgin males approach and court females significantly earlier than nonvirgin males. As compared with nonvirgin males, virgin males are ≈1.6 times more likely to approach and 1.8 times more likely to court females, and four times more likely to achieve mating. This may be attributed to depletion of sperm and accessory gland materials and reduced ability to respond to female sex pheromones in nonvirgin males. The number of attempts by males to acquire mates may be one of the traits that females assess before choosing their mates.

Influence of host fruit and conspecifics on the release of the sex pheromone By Toxotrypana curvicauda males (Diptera: Tephritidae).

ABSTRACT The release of tephritid sex pheromones depends significantly on the age of the male, the social context (presence of conspecifics) and chemical context (host volatiles). In this study, the influence of host fruit and conspecific (males and females) on the emission of the pheromonal compound 2-methyl-6-vinylpyrazine (2,6 mvp) by Toxotrypana curvicauda (Gerstaecker) males was investigated under laboratory conditions. Males were divided into one control group (nonexposed to treatment) and five experimental groups were placed 1 hr before volatile collection with: 1) host fruit (unripe papaya), 2) two females, 3) two males, 4) host fruit plus two females, and 5) host fruit plus two males. The volatiles were sampled by means of solid phase microextraction and analyzed with gas chromatography-mass spectrometry, with a focus on 2,6 mvp. Males emitted volatiles from the first day after adult emergence. The maximum peak and the temporal pattern of 2,6 mvp release were modified by the presence of host fruit and conspecific males or females. On day 5, males in the presence of fruit maintained a constant release of 2,6 mvp while the presence of conspecific caused a decrease of pheromone release. The release of 2,6 mvp was increased significantly in males exposed to both types of stimuli simultaneously. The stimuli (fruit and conspecifics) modified the release of 2,6 mvp, however the effect depended on male age.

Tissues Involved in Sex Pheromone Production in Phyllophaga obsoleta (Coleoptera: Scarabaeoidea: Melolonthidae)

ABSTRACT Females of Phyllophaga obsoleta (Blanchard) (Coleoptera: Scarabaeoidea: Melolonthidae) perform “sexual calling” with their protractile genital chamber (PGC) exposed to release substances that attract males. Histological aspects of the PGC and accessory glands (AGs) of P. obsoleta females were studied. Studies with light microscope and transmission electron microscope revealed exocrine tissue in the posterior section of the PGC, where it might be producing the attractants. This epithelial gland is formed by a basement membrane, a hypodermis for substance production, secretion, and transport (cells, nucleus, mitochondria, endoplasmic reticulum, Golgi complex, and presence of folds in the plasma membrane), as well as evidence of the substance to be secreted to the outside (connecting cuticular pores to plasma membrane). Histological similarities between AG types I and II were observed, although only the PGC had properties of class I cells. These results suggest that the posterior section of the P. obsoleta PGC is involved in sex pheromone production.

Extraction with SPME and Synthesis of 2-Methyl-6- vinylpyrazine by a 'One Pot' Reaction Using Microwaves

A synthesis of 2-methyl-6-vinylpyrazine was carried out by way of a ‘one pot’ reaction. In order to establish the efficiency of this synthesis the extraction of the volatiles released by male papaya fruit flies was performed by SPME (solid phase micro-extraction). The compound was separated and identified using GC/MSD (gas chromatography/mass spectrometry detector).

Antiemetic Inhibits Conditioned Taste Aversion, But Not the Hypophagia Induced by Epinephrine

It has been shown that relatively high doses of epinephrine (E) injected intraperitoneally (IP) produce hypophagia and conditioned taste aversion (CTA) in rats. We examined the possibility that E effects involve malaise. For this purpose, changes in saccharin preference induced by E injected IP (100 microg/kg) were determined after a previous administration of trimethobenzamide (TMB, 5 mg/kg), an antiemetic agent. E alone decreased saccharin preference by 54% (p < 0.01), but only by 16% (not significant) in the presence of TMB. In contrast, the injection of 75 or 100 microg/kg E reduced food intake by 50 and 85%, respectively (p < 0.01), regardless of previous injection of TMB. In conclusion, the results suggest that E-induced malaise is not the direct cause of the hypophagia it elicits.

Oviposition by Toxotrypana curvicauda (Diptera: Tephritidae) in Small to Medium-Size Cuaguayote and Papaya Fruits with Low Sugar Content

Summary The papaya fruit fly, Toxotrypana curvicauda Gerstaecker (Diptera: Tephritidae), has several known hosts apart from the commercially valuable papaya (Carica papaya L.; Capparales: Caricaceae), among them Jacaratia mexicana A. DC. (Capparales: Caricaceae), known in Mexico as cuaguayote. Most studies on the papaya fruit fly have been carried out with C. papaya and have neglected the other known host for this fly. We characterized papaya and cuaguayote fruits in which T. curvicauda oviposits in terms of color, length, hardness and thickness of flesh, total solids (as °Brix), and the section (proximal, middle, and distal) of the fruit where the eggs were deposited. Toxotrypana curvicauda females oviposited in medium-size to small but not large fruits of either papaya or cuaguayote. Moreover, females oviposited only in low—sugar content papaya fruits, and mostly (about 88%) in low—sugar content cuaguayote fruits with a small fraction (about 12%) of the eggs laid in medium-size and large fruits. The other variables had no effect on oviposition behavior. This is the first report of T. curvicauda oviposition behavior with respect to cuaguayote.

Effects of male age and mating status on response to the female sex pheromone of Copitarsia decolora (Lepidoptera: Noctuidae)

Abstract The effects of male age and mating status on the behavioral response of Copitarsia decolora (Guenée) males to the glandular extract of the female sex pheromone were studied by conducting wind tunnel bioassays and electroantennography (EAG). To study the effect of age, 2–3, 4–5, 6–7, 8–9, 10–11 day old males were used to measure attraction in the wind tunnel. To study the effect of age on virgin male antenna depolarization, Individual males 3-, 6- and 9-days old were used. The effect of male mating status was studied with 4–6 day old males and subsequent pheromone response was measured after a period of 24 and 48 h. Both male age and mating status significantly affected male response to the female sex pheromone. In the wind tunnel, male attraction to the extract reached its maximum in males 4–7 days old and then decreased as moth age increased. The glandular extract provoked a significantly greater depolarization of the antennae of 6 day old males than in 3 and 9 day old males. In the wind tunnel, virgin males were more attracted to female extracts than mated males. Significantly greater depolarization was observed in the antennae of virgin than mated males.