Heliothis subflexa, a Host for Cardiochiles nigriceps1

Lewis, W. J.; Brazzel, J. R.; Vinson, Bradleigh S.

doi:10.1093/jee/60.2.615

Cited by 13 publications

(11 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Reported rates of parasitism for H. virescens on tobacco vary from 25% (28) to 72% (29), and rates as high as 96% have been observed on cotton (30). In contrast, Roach (31) found no parasitism of H. subflexa on P. angulata, whereas Lewis et al (32) reported 2% parasitism and Sisterson and Gould (27) found 7% parasitism. It has been suggested that these low rates of parasitism are below expectations based on the protection afforded by the calyx alone (33), indicating that other factors must be involved.…”

Section: Resultsmentioning

confidence: 99%

Biochemical crypsis in the avoidance of natural enemies by an insect herbivore

Moraes

Mescher

2004

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Plant-herbivore interactions provide well studied examples of coevolution, but little is known about how such interactions are influenced by the third trophic level. Here we show that larvae of the specialized lepidopteran herbivore Heliothis subflexa reduce their vulnerability to natural enemies through adaptation to a remarkable and previously unknown feature of their host plant, Physalis angulata: The fruits of this plant lack linolenic acid (LA), which is required for the development of most insects. By overcoming this nutritional deficiency, H. subflexa larvae achieve numerous advantages. First, they gain near-exclusive access to a food resource: we demonstrate that closely related Heliothis virescens larvae cannot develop on P. angulata fruit unless the fruit are treated with LA. Second, they reduce their vulnerability to enemies: LA is a key component of volicitin, an elicitor of plant-volatilesignaling defenses. We demonstrate that volicitin is absent in the oral secretions of fruit-feeding caterpillars, that the volatile profiles of plants induced by fruit feeding differ from those induced by leaf feeding or by feeding on LA-treated fruit, and that the former are far less attractive to female Cardiochiles nigriceps parasitoids. Finally, they render themselves nutritionally unsuitable as hosts for enemies that require LA for their own development: we show that C. nigriceps larvae fail to develop within the bodies of fruit-feeding caterpillars but do develop in caterpillars feeding on LA-treated fruit. Thus, H. subflexa larvae not only overcome a serious dietary deficiency but also reduce their vulnerability to natural enemies through a form of ''biochemical crypsis.'' T he vulnerability of insect herbivores to attack by predators and parasitoids is often mediated by interactions with the host plant on which the herbivore feeds (1-3). Specialist herbivores that have overcome certain plant defenses may subsequently co-opt those defenses, for example, by sequestering chemical toxins produced by the plant within their bodies as a defense against their own enemies (2, 4-6). Plants, in turn, often respond to herbivory by releasing volatile chemical compounds that are attractive to predators and parasitoids that are natural enemies of the herbivores (7,8). Thus, the particular physical and physiological characteristics of the host plant are thought to be major features influencing the vulnerability of insect herbivores to attack by predators and parasitoids, and adaptation to those specific characteristics may be expected to play an important role in avoiding attack by natural enemies (9-11). Lill et al. (3) demonstrated a strong effect of host-plant identity on parasitism rates and suggested that these differences might be influenced by features of the host plant including plant-volatile-related differences in parasitoid attraction and retention but did not address the specific mechanisms that might underlie such differences.In this article we describe behavioral and physiological adaptations of the speciali...

show abstract

Section: Resultsmentioning

confidence: 99%

Biochemical crypsis in the avoidance of natural enemies by an insect herbivore

Moraes

Mescher

2004

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…H. virescens is highly polyphagous, feeding on 37 species of plants in 14 different plant families (Sheck and Gould 1993). This study was motivated by survey data on parasitism rates of H. virescens and H. subflexa on their respective host plants by the braconid parasitoid Cardiochiles nigriceps (Lewis et al 1967). 1).…”

Section: Introductionmentioning

confidence: 99%

The Inflated Calyx of Physalis angulata: A Refuge from Parasitism for Heliothis subflexa

Sisterson¹

1999

Ecology

View full text Add to dashboard Cite

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology. Abstract.Heliothis subflexa and H. virescens are the only known hosts of the parasitoid Cardiochiles nigriceps. H. subflexa, a specialist on plants in the genus Physalis, appears to have a lower parasitism rate compared to the polyphagous H. virescens. Physalis is characterized by producing fruits that are concealed within a paper-like lantern, within which H. subflexa larvae feed. We conducted an experiment to determine whether H. subflexa is protected from parasitism by feeding within the lanterns of Physalis. We compared parasitism rates of wild H. subflexa larvae on normal P. angulata plants to parasitism rates of larvae on plants that had the tips of all the lanterns removed to allow parasitoids access to the larvae. A higher percentage of larvae were parasitized on plants with cut lanterns (48.25%) than uncut lanterns (6.74%). A second experiment was conducted to determine whether volatiles released from cut lanterns influenced the searching of C. nigriceps. This experiment consisted of the two treatments from the previous experiment and a third in which the tips of lanterns were removed and the resulting hole was stapled shut. Cutting plants did not make the plants more attractive to searching parasitoids. We conclude that H. subflexa gains protection from parasitism by feeding within the inflated (;alyx of Physalis.

show abstract

“…Throughout the southeastern United States, the predominant parasitoid of both species is Cardiochiles nigriceps Vierick (Hymenoptera: Braconidae) (Lewis et al 1967). This specialist endoparasitoid is only known to develop in Heliothis larvae (Lewis and Vinson 1971).…”

mentioning

confidence: 99%

“…On cotton, parasitism rates as high as 96% have been recorded (Lewis et al 1972). For H. subflexa larvae, field collections have consistently shown much lower rates of parasitism: Roach (1975) found no parasitism, whereas Lewis et al (1967) reported rates from 2% to 9%.…”

mentioning

confidence: 99%

Behavioral Adaptations Increase the Value of Enemy-Free Space for Heliothis Subflexa, a Specialist Herbivore

Oppenheim

Gould

2002

Evolution

View full text Add to dashboard Cite

Abstract. We investigated the importance of specialized behaviors in the use of enemy-free space by comparing the host-use behavior of two closely related moths, Heliothis subflexa Guenee and H. virescens Fabricius. Heliothis subflexa is a specialist on plants in the genus Physalis, whereas H. virescens is an extreme generalist, feeding on plants in at least 14 families. Heliothis subflexa uses the inflated calyx surrounding Physalis fruits as enemy-free space, and field rates of parasitism for H. subflexa on Physalis are much lower than for H. virescens on tobacco and cotton, common hosts found in the same habitat as Physalis. If Physalis' architecture were solely responsible for H. subflexa's low rates of parasitism on Physalis, we predicted that H. virescens larvae experimentally induced to feed on Physalis would experience parasitism rates similar to those of H. subflexa. We found, however, that specialized host-use and hostacceptance behaviors are integral to the use of enemy-free space on Physalis and strongly augment the effects of the structural refuge. In laboratory assays, we found considerable differences between the larval behavior of the specialist, H. subflexa, and the generalist, H. virescens, and these contributed to H. subflexa's superior use of enemy-free space on Physalis. We tested the importance of these behavioral differences in the field by comparing parasitism of H. virescens on Physalis, H. virescens on tobacco, and H. subflexa on Physalis by Cardiochiles nigriceps Vierick, a specialist braconid parasitoid. For H. virescens, a threefold decrease in parasitism occurred when feeding on Physalis (mean parasitism Ϯ SEM ϭ 13 Ϯ 4%) rather than tobacco (43 Ϯ 4%), a difference we attribute to the structural refuge provided by Physalis. However, parasitism of H. virescens on Physalis was more than ten times as great as that of H. subflexa on Physalis (1 Ϯ 4%), supporting the hypothesis that specialized behaviors have a substantial impact on use of Physalis as enemy-free space. Behavioral adaptations may be central to the use of enemy-free space by phytophagous insects and may act as an important selective force in the evolution of dietary specialization. The question of why insect herbivores eat what they do has long intrigued biologists. With the huge variety of edible plants available in the world, why should a herbivore limit itself to one or a few plant species? Yet, the vast majority of phytophagous insects are dietary specialists (Farrell and Mitter 1993;Thompson 1994), feeding on plants from a single genus or a single family (Menken and Roessingh 1998). Less than 10% of all phytophagous insects are generalists, feeding on plants from three or more families (Bernays and Graham 1988). This predominance of specialist feeders suggests that insects with narrow host ranges may enjoy some selective advantage over generalist feeders.The ability to use enemy-free space, defined by Berdegue et al. (1996, p. 203) as ''a discrete moment in evolutionary time where the fitness of the prey, under select...

show abstract

Heliothis subflexa, a Host for Cardiochiles nigriceps1

Cited by 13 publications

References 0 publications

Biochemical crypsis in the avoidance of natural enemies by an insect herbivore

Biochemical crypsis in the avoidance of natural enemies by an insect herbivore

The Inflated Calyx of Physalis angulata: A Refuge from Parasitism for Heliothis subflexa

Behavioral Adaptations Increase the Value of Enemy-Free Space for Heliothis Subflexa, a Specialist Herbivore

Contact Info

Product

Resources

About