Contributions of diet quality and diapause duration to the termination of larval diapause in khapra beetle, Trogoderma granarium (Coleoptera: Dermestidae)

Shivananjappa, S.; Fields, P.; Laird, R. A.; Floate, K. D.

This item is private.

Contributions of diet quality and diapause duration to the termination of larval diapause in khapra beetle, Trogoderma granarium (Coleoptera: Dermestidae)

Simple item page

Full item details

dc.contributor.author: Shivananjappa, S.; Fields, P.; Laird, R. A.; Floate, K. D.
dc.date.accessioned: 2023-04-17T15:36:17Z
dc.date.available: 2023-04-17T15:36:17Z
dc.date.issued: 2019-11-15
dc.description.abstract - en: Larvae of khapra beetle, Trogoderma granarium (Coleoptera: Dermestidae) have an unusual diapause during which they may sporadically feed for several years, but not complete development. Diapausing larvae have an enhanced tolerance to starvation, insecticides and extreme temperatures. Thus, knowledge of factors that terminate larval diapause may aid in the control of this pest. In the current study, we assessed the effect of diet quality (five mixtures of fresh and spent diet in a replacement series) on diapause termination for diapausing larvae from laboratory cultures aged 3, 10, or 14 months. Larvae (n = 10 replicates for each combination of diet quality and culture, 10 larvae/replicate) were held at 30 °C and observed at different intervals over the course of 188 days to record larval mortality and larval pupation (= diapause termination). Larvae were least able to survive on diets of lower quality; i.e., 88% mortality after 188 days on 0% fresh diet versus 8% mortality on 100% fresh diet (averaged across cultures). Larvae were most likely to terminate diapause on diets of higher quality; i.e., 87% termination after 188 days on 100% fresh diet versus 0% termination on 0% fresh diet (averaged across cultures). Diapausing larvae from older cultures were least likely to terminate diapause and least likely to survive. On 100% fresh diet, diapause termination of larvae from cultures aged 3, 10 and 14 months was 93, 91, and 78%, respectively. On 0% fresh diet, mortality of larvae from cultures aged 3, 10 and 14 months was 67, 97, and 100%, respectively. These results indicate that diapausing larvae can accumulate the nutrients required to terminate diapause and complete development when provided with an opportunity to do so. However, the window of opportunity continues to shrink the longer the larvae remain in diapause.
dc.description.plainlanguage - en: Khapra beetle is a pest of stored grains with an unusual lifecycle. Their larvae can enter a state of diapause during which they may sporadically feed for several years, but not complete development. Diapausing larvae have an enhanced tolerance to starvation, insecticides and extreme temperatures. By identifying the factors that terminate larval diapause, it may be possible to ‘force’ larvae to end their diapause and become more susceptible to methods of control. In the current study, we fed diapausing larvae on five types of diet (ranging from ‘good’ to ‘poor’) to test the effect of food quality on larval diapause. For this test, we used larvae of different ages that had been in diapause for about 3, 10, or 14 months. For each combination of diet type and age, we held larvae at 30 °C for a period of 188 days and made observations on larval mortality and larval pupation (= diapause termination). We found that larvae were least able to survive on diets of poor quality. Larvae were most likely to terminate diapause on diets of higher quality. Larvae that had been in diapause for longer periods of time were least likely to terminate diapause and least likely to survive. These combined results suggest that when given the opportunity, larvae in diapause will accumulate the nutrients required to terminate diapause and complete development. However, the longer the larvae have been in diapause, the harder it is for them to accumulate the necessary nutrients and the greater the chances of them dying.
dc.description.plainlanguage - fr: Le coléoptère de Khapra est un ravageur des grains entreposés dont le cycle de vie est inhabituel. Leurs larves peuvent entrer en diapause, une période durant laquelle elles peuvent s’alimenter sporadiquement pendant plusieurs années, sans toutefois achever leur développement. Les larves en diapause ont une tolérance accrue à la famine, aux insecticides et aux températures extrêmes. En répertoriant les facteurs qui mettent fin à la diapause larvaire, il pourrait être possible de « forcer » les larves à mettre fin à leur diapause et à devenir plus sensibles aux méthodes de lutte. Dans la présente étude, nous avons donné à des larves en diapause cinq types de régime alimentaire (de « bon » à « mauvais ») afin de vérifier l’effet de la qualité de la nourriture sur la diapause larvaire. Pour cet essai, nous avons utilisé des larves d’âges différents qui étaient en diapause depuis environ 3, 10 ou 14 mois. Pour chaque combinaison de type de régime alimentaire et d’âge, nous avons maintenu les larves à 30 °C pendant une période de 188 jours et avons observé la mortalité larvaire et la nymphose larvaire (= fin de la diapause). Nous avons constaté que les larves sont les moins capables de survivre avec des régimes alimentaires de mauvaise qualité. Les larves étaient plus susceptibles de mettre fin à la diapause avec une ration de meilleure qualité. Les larves qui étaient en diapause depuis plus longtemps étaient les moins susceptibles de mettre fin à la diapause et les moins susceptibles de survivre. Ces résultats combinés donnent à penser que lorsqu’elles en ont l’occasion, les larves en diapause accumulent les nutriments nécessaires pour mettre fin à la diapause et achever leur développement. Cependant, plus les larves sont en diapause depuis longtemps, plus il leur est difficile d’accumuler les nutriments nécessaires et plus grandes sont leurs chances de mourir.
dc.identifier.citation: Shivananjappa, S., Fields, P., Laird, R. A., & Floate, K. D. (2020). Contributions of diet quality and diapause duration to the termination of larval diapause in khapra beetle, Trogoderma granarium (Coleoptera: Dermestidae). Journal of Stored Products Research, 85. https://doi.org/10.1016/j.jspr.2019.101535
dc.identifier.doi: https://doi.org/10.1016/j.jspr.2019.101535
dc.identifier.issn: 1879-1212
dc.identifier.uri: https://open-science.canada.ca/handle/123456789/189
dc.language.iso: en
dc.publisher: Elsevier
dc.rights.openaccesslevel - en: Green
dc.rights.openaccesslevel - fr: Vert
dc.subject - en: Agriculture
dc.subject - fr: Agriculture
dc.subject.en - en: Agriculture
dc.subject.fr - fr: Agriculture
dc.title - en: Contributions of diet quality and diapause duration to the termination of larval diapause in khapra beetle, Trogoderma granarium (Coleoptera: Dermestidae)
dc.title.fosrctranslation - fr: Contributions of diet quality and diapause duration to the termination of larval diapause in khapra beetle, Trogoderma granarium (Coleoptera: Dermestidae)
dc.type - en: Article
dc.type - fr: Article
local.article.journaltitle: Journal of Stored Products Research
local.article.journalvolume: 85
local.peerreview - en: Yes
local.peerreview - fr: Oui