Mating behavior of Cnephasia jactatana (Lepidoptera: Tortricidae), an important pest of kiwifruit.

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 approximately 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.

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.

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.

The role of conditioned taste aversion in the hypophagia induced by intraperitoneal epinephrine and glucose.

It has been repeatedly shown that relatively high doses of epinephrine (E) and glucose (G) injected intraperitoneally (ip) produce hypophagia in fasted rats. In the present work we used a conditioned taste aversion (CTA) paradigm in order to test whether this effect could be due to "malaise." We determined the effect on food intake and saccharin preference with the following treatments: (a) E ip 100 and 250 micrograms/kg; (b) E ip 250 micrograms/kg with or without previous alpha 1 plus beta adrenergic blockade; (c) G ip 3.5 and 4 g/kg. Both doses of E significantly reduced food intake more than 75% but only the high dose produced a significant (50%) reduction in saccharin preference. Blockade of alpha 1 and beta adrenergic receptors completely suppressed the E-induced hypophagia but attenuated only slightly the taste aversivon effect. Both doses of G decreased food intake but only the high dose reduced saccharin preference; part of these effects would appear to be due to the high osmolarity of the solution. The present results indicate that E and G may induce CTA in our experimental conditions. However, their hypophagic and aversive effects seem to be elicited by different mechanisms.