Abstract
Simple SummarySuccessful integrated pest management of horticultural crops requires the evaluation of natural enemies used in biological control. To improve the mass rearing of Chelonus inanitus (L.) in the factitious host Ephestia kuehniella Zeller, we investigated the influence of host age and number of females parasitizing simultaneously on quality parameters evaluated in the commercial production of biological control agents, such as overall rearing success, duration of life cycle and body size. Under semi-field conditions, we investigated how the competition among females impacted the parasitism success on important pests Spodoptera exigua (Hübner) and S. littoralis (Boisduval). For the parasitoid mass rearing optimization, mature eggs seem to be more convenient because they increased the female percentage in the offspring and shortened the parasitoid life cycle. Furthermore, a high number of females parasitizing simultaneously reduced the emergence of non-parasitized hosts. Under more realistic conditions, the parasitoid effectively controlled both pests, but S. exigua may be a more convenient host because the parasitoid offspring was much larger. With this research, we provide a foundation that aims to better manage these cosmopolitan, highly polyphagous pests that exhibit long-distance migratory potential, alongside the potential use of this natural enemy.Chelonus inanitus (L.) is an egg-larval parasitoid of noctuids Spodoptera exigua (Hübner) and S. littoralis (Boisduval), whose mass rearing or real potential has not been targeted yet. To improve the rearing in the factitious host Ephestia kuehniella Zeller, we investigated the influence of host age and number of females parasitizing simultaneously on the overall rearing success, the influence of host age on the life cycle, and the influence of host species on the parasitoid body size. The proportion of emerging C. inanitus was higher from young host eggs, but more females emerged from mature eggs. Under high parasitoid competition, we observed a reduction in non-parasitized hosts without reducing parasitoid emergence. The parasitoid life cycle was longer in females, but the mismatch between sexes was smaller in mature eggs. The parasitoid size was smaller in the factitious host than in the natural hosts. Under semi-field conditions, we investigated the competition among parasitoid females on the overall parasitism success. The reproductive parasitism was more successful in S. exigua than in S. littoralis, and the maximum emergence was reached with three and four females, respectively. The control of S. littoralis may be attributed to the high developmental mortality, a non-reproductive parasitism that is often underestimated.
Highlights
Spodoptera pests (Lepidoptera: Noctuidae) are highly feared in many crops globally.They are highly polyphagous, can be found on almost all types of commodities of plants and exhibit a long-distance migratory potential [1]
To optimize C. inanitus mass rearing under laboratory conditions, we firstly studied the influence of the host age and the number of parasitoid females on C. inanitus development, by evaluating the percentages of C. inanitus adults per offered eggs, C. inanitus females per emerged parasitoids, and E. kuehniella adults per offered eggs in the offspring
The percentage of C. inanitus females emerged was dependent on the host age (F1,36 = 5.67, p = 0.02) and it was higher when females parasitized mature eggs (Table 1)
Summary
Spodoptera pests (Lepidoptera: Noctuidae) are highly feared in many crops globally.They are highly polyphagous, can be found on almost all types of commodities of plants and exhibit a long-distance migratory potential [1]. Spodoptera littoralis (Boisduval) (the cotton leafworm), included in the EPPO A2 quarantine list [6], lives in the Palearctic region and can attack over 40 families of plants containing about 87 species of economic importance [1,7,8,9]. This species is present in the protected crops of Southeastern Spain [4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
