Fernando S. Zucoloto

Feeding habits of Ceratitis capitata (Diptera: Tephritidae): Can larvae recognize a nutritionally effective diet?

Abstract Larvae of Ceratitis capitata were tested for preference for different diets based on the ingredients of the standard diet used to rear flies in the laboratory. The nutritional value of these diets was also determined. The results showed that larvae are able to recognize the diets that are best from a nutritional viewpoint. When chemically defined diets were tested, larvae always preferred those containing the largest amount of protein, except for older larvae, which preferred protein-free diets. In a threshold study, larvae were able to recognize as little as 0.1 g yeast/100 ml diet and 1.5 casein/100 ml diet.

The influence of host nutritive value on the performance and food selection in Ceratitis capitata (Diptera, Tephritidae)

Abstract One of the purposes of this study was to verify the nutritive value of different parts of the same fruit for larvae of Ceratitis capitata; another was to ascertain if the larvae select the part of the fruit with better nutritive value, and also if the females prefer to oviposit in it. The results indicate that: (1) the lower part of the fruits tested has greater quantities of solute and sugars and therefore may have better nutritive value; (2) the larvae chose the more adequate part of the fruit; (3) when placed on the less nutritive part, they move to the more adequate part; and (4) it is not clear if the females prefer to oviposit in the part of the fruit which is more adequate for the larvae.

Self-selection and perception threshold in adult females of Ceratitis capitata (Diptera, Tephritidae)

Abstract Experiments were conducted on adult females of Ceratitis capitata to determine (1) whether feeding a protein source in adulthood increases egg production (2) whether the females are self-selective with respect to feeding, and (3) whether deprivation of a protein source alters the perception threshold for this nutrient. The results obtained showed: that when a protein source is ingested throughout adult life, egg production is increased; that the females proved to be self-selective with respect to the choice of food, and that deprivation of a protein source alters the perception threshold.

Oviposition Behavior of Ceratitis capitata Wiedemann (Diptera: Tephritidae): Association Between Oviposition Preference and Larval Performance in Individual Females

The oviposition preference and larval performance of females of Ceratitis capitata (Wiedemann) were examined. Wild or laboratory-reared females were tested for oviposition preference in relation to papaya fruit in different stages of ripeness, as well as to two different fruits: papaya and apple. The results demonstrated that both laboratory-reared and wild females preferred ripe papaya fruit compared to unripe fruit for oviposition, and that ripe papaya was the best for larval performance. When oviposition preference was tested with different fruits (papaya and apple), both wild and laboratory-reared larvae developed better in papaya. However, only wild females showed a preference for oviposition on papaya as opposed to apple. Laboratory-reared females showed no oviposition preference on fruits that resulted in better larval performance.

Effects of flavour and nutritional value on diet selection by Ceratitis capitata larvae (Diptera, Tephritidae)

Abstract Diet flavour and nutritional value were tested for influence on diet selection by Ceratitis capitata larvae. The results indicate that nutritional value is the predominant factor in diet selection and that flavour is a determinant only when the diets to be selected are nutritionally more effective. When placed on a less effective diet, the larvae move to another of better nutritional value. Even after feeding on a less effective diet for 3 days, the larvae will select a diet of more effective nutritional value.

Nutritional value and selection of different diets by adult Ceratitis capitata flies (Diptera, Tephritidae)

Abstract Experiments were conducted on adult Ceratitis capitata flies with two major objectives: to determine (1) the influence of different dietary protein and lipid concentrations on egg production, and (2) whether adult females select nutrients that provide better efficiency in terms of egg production. Sometimes proteins were found to be important for egg production after the pre-oviposition phase, with no difference among the various concentrations tested. Lipids were not essential for egg production. Proteins and lipids were poorly utilized as sources of energy, probably because of the low ingestion of these nutrients by the flies. Sucrose may be the base for the amount of diet ingested. It is not clear whether the females are able to select nutrients to increase egg producton, up to the 15th day.

Influence of chorion ingestion on the performance of Ascia monuste and its association with cannibalism

1. In some lepidopterans, the newly hatched caterpillars feed on chorion (animal protein) as their first food. This is also a frequent behaviour of newly hatched caterpillars of Ascia monuste.

Egg cannibalism in Ascia monuste in the field; opportunistic, preferential and very frequent

Newly hatched caterpillars of the specialist herbivorous species Ascia monuste (Lepidoptera, Pieridae) feed on egg chorion before ingesting plant material. They also ingest their exoskeletons and perform egg cannibalism in both the field and the laboratory. Females lay eggs on plants which already have conspecifics (eggs and/or caterpillars) leading to the observation of cannibalism in the field. Two favorable conditions are required for such an occurrence: (1) eggs laid close together on the same leaf, and (2) the finding by older caterpillars of eggs on the same plant. Oviposition preference experiments in cages showed that females do not avoid laying on plants with eggs. However, they do avoid laying eggs on plants predated by caterpillars. All instars perform cannibalism in the field and, in addition to this, the ingested eggs are healthy and cannibalism occurs in the presence of abundant food. The ingestion of eggs from their own clutch was more intense when the clutch was large. Contact with eggs is also important for cannibalism. Caterpillars ingested healthy eggs during three successive days. According to the results, it is possible to state that egg cannibalism in A. monuste is opportunistic, preferential and highly frequent and that there is a tolerance to a diet based on animal protein in this species. Since A. monuste obtains nutrients from both animal and vegetable resources, it is probably better to consider it as opportunistic omnivorous.

Effect of host age on the oviposition and performance of Ascia monuste Godart (Lepidoptera: Pieridae)

Ascia monuste Godart, known as the kale caterpillar, has a specialized diet on Brassicaceae and represents one of the main herbivores of this family in the Neotropical region. The objective of the present study was to determine the performance and oviposition preference of A. monuste for common kale Brassica oleracea (Brassicaceae, var. acephala) of different ages. The parameters used to assess performance were time to pupation and emergence, emergence rate, digestive indices, relative consumption and growth rates, number of eggs per female, hatching rate, and weight of the imagoes. Chemical and physical properties of young and old kale leaves were determined. In general, caterpillars feeding on new leaves showed better performance than those feeding on old leaves. However, no significant difference in the number of eggs per female was observed, indicating a strategy of compensation, as old leaves contain a lower amount of nitrogen and are harder than young leaves. A. monuste females prefer to lay eggs on young leaves.

Importance of larval migration (dispersal) for the survival of Ascia monuste (Godart) (Lepidoptera: Pieridae)

Insect species whose larvae have high mobility, such as Ascia monuste (Godart), show a poor discriminatory oviposition behavior with respect to the quantity of food. Such behavior in A. monuste is influenced positively by the spatial and temporal abundance of kale (Brassica oleracea Var. acephala), its main host, in nature. A. monuste caterpillars frequently migrate in search of food to complete their development and even smaller larval clusters at about 20 individuals are not supported by the resources provided by a medium-size kale plant. Migration (dispersal) of 5th-instar larvae was necessary both in groups feeding on plants confined in cages and on plants growing in nature, and migration was successful when the plants were close to one another. The oviposition of A. monuste females on isolated plants was similar to the oviposition in clustered plants in nature. Ovipositing on isolated plants reduced the survival of immatures since larval migration was impaired by the absence of nearby host plants (experimental condition). Predation of larvae on the plant of origin was the major cause of A. monuste mortality in nature.