Physical traits and fitness of cold-induced lethargic Diachasmimorpha longicaudata (Hymenoptera: Braconidae) adults

ABSTRACT

The chilled adult technique is a suitable strategy for the mass-release of insects for the area-wide management of insect pests. Chilling may have undesirable effects on the released insects. The relationship between physical traits and the effects of cold-induced lethargy on the fitness of Diachasmimorpha longicaudata has not been fully explored. In the present study, we evaluated the relationship between weight, size, and water and lipid content in D. longicaudata subjected to cold-induced lethargy at 9, 6, and 3°C, and the effects of cold induction on the survival, flight ability, and fecundity of parasitoid adults. During gradual chilling from 15°C to 3°C over a 45 min period, we observed that most wasps became lethargic at 9°C. The tibias of wasps that became lethargic at 3°C were larger than those of parasitoids that became lethargic at 9 and 6°C. Body water and lipid contents were higher in lethargic females chilled at 3°C, but no differences were observed in males. Lethargic males experienced reduced flight ability compared with the control, whereas fecundity was reduced only in lethargic females that had been exposed to 3°C. The survival rate was lower in both sexes. Our results suggest that greater body size and higher water and lipid contents delay the onset of cold-induced lethargy, but do not prevent negative effects on survival, fecundity, and flight ability in D. longicaudata. This study will help the advancement of parasitoid-release field programmes that use the chilled adult technique.

KEYWORDS:

• Chilled insect technique
• parasitoid attributes
• cold starvation
• parasitoid size
• lipids contents

Acknowledgments

We wish to express our sincere gratitude to Dr. Jaime Gómez Ruiz⁺ for his invaluable support at the outset of this research. We thank Maritza Juárez Durán, director of the National Fruit Fly Program (SADER-IICA, Mexico), for the authorisation to perform this study at the facilities of the Moscafrut Program. We extend our thanks and gratitude to the staff of the Biological Control Department for their invaluable support in carrying out the experiments, and to the Mubarqui Company (Mexico) for providing the equipment for performing the experiments. The first author gratefully acknowledges a scholarship (587809) for graduate studies granted by the El Consejo Nacional de Humanidades, Ciencia y Tecnología (CONAHCyT, Mexico).

Disclosure statement

No potential conflict of interest was reported by the author(s).