Influence of adult diet on fitness and reproductive traits of the egg parasitoid Anagrus virlai (Hymenoptera: Mymaridae), a potential biocontrol agent against the corn leafhopper

Abstract

Dalbulus maidis is the most important leafhopper pest of maize in the Americas. Anagrus virlai is an egg parasitoid commonly associated with the corn leafhopper. We evaluated whether the performance of A. virlai is dependent on different diets provided during 24 hr or throughout adult female lifetime. Additionally, functional response of A. virlai on D. maidis eggs using maize leaves containing honeydew plus honey was described. A. virlai is a mostly pro‐ovigenic autogenic species whose females are able to parasitize eggs immediately after emergence. We found that wasps oviposit the majority of their eggs in the first day of their adult life. Realized lifetime fecundity and lifetime potential fecundity did not differ significantly among treatments, but longevity and egg production increased when honey was added to diet. Data were consistent with an intermediate functional response between type II and III, but closer to type II, indicating a high parasitism rate at low host densities and a decrease in the oviposition rate at high host densities, due to a possible egg limitation. Our results suggest that carbohydrate food sources (honeydew and honey) might not be the factor limiting reproductive success during the first 24 hr. Food supply, however, might influence egg maturation and survivorship of wasps, thus potentially enhancing biological pest control when hosts are scarce in the course of the first few days of adulthood.

Ovigeny strategy of the parasitic wasp Cosmocomoidea annulicornis (Hymenoptera: Mymaridae): effect of female age, feeding and host availability on reproductive traits

“…In accordance with our findings, these studies also demonstrated that diet positively influenced longevity in females and that, when fed with sugary substances, females lived longer and laid more eggs. Nevertheless, in the case of the highly pro-ovigenic wasp A. virlai, although feeding influenced longevity, it did not significantly affect the fecundity of the females, since they laid almost all of their mature eggs during the first few days of life (Hill et al, 2020).…”

“…In fact, several species (including species belonging to the genus Cosmocomoidea (formerly Gonatocerus)) display this type of reproductive strategy (Irvin and Hoddle, 2009), evidenced by female emergence with a mature complement of eggs and no further egg maturation recorded. However, exceptions to this observed trend have been documented for some mymarid species: Anaphes iole Girault, A. listronoti Huber (Riddick, 2005;Boivin and Martel, 2012;Boivin and Ellers, 2016) and Anagrus virlai Triapitsyn (Hill et al, 2020) display OIs between 0.70 and 0.90, for which they are considered highly pro-ovigenic, but capable of maturing eggs in addition to their initial egg load.…”

Effect of egg production dynamics on the functional response of parasitoids

“…[69]. On the other hand, in the egg parasitoid Anagrus virlai Triapitsyn (Mymaridae), the number of parasitized eggs decreases as females age, and wasps experience a double egg maturation process [30]. Palottini [62], using a similar experimental design and statistical analysis to the one we employed, found that the egg production rate of Gonatocerus sp.…”

“…Parasitoid longevity influences the extent to which parasitoid becomes time-limited. To maximize longevity in the fleld, many parasitoids require a carbohydrate source such as nectar, hemipteran honeydew, or they might feed directly on their hosts [29,30. However, the variability in nutrient income caused by the use of external stochastic sources of nutrients can entail great risks of starvation.…”

Diets for Tamarixia triozae adults before releasing in augmentative biological control

“…Several studies report that adult diets can change parasitoids' lifetime oviposition patterns (Bai and Smith 1993;Wade et al 2008;Hill et al 2020). This suggests that we may be able to modify parasitoids' lifetime oviposition trajectory by tailoring their adult diets before release to achieve effective augmentative biological control under different circumstances.…”