Functional response of 3 green lacewing species (Neuroptera: Chrysopidae) to Leucoptera coffeella (Lepidoptera: Lyonetiidae)

Pyriproxyfen exposure compromises cocoon spinning and damages the Malpighian tubules of the nontarget predator Ceraeochrysa claveri (Neuroptera: Chrysopidae)

Pyriproxyfen has been extensively employed in the Neotropical region for agricultural pest management and insect vectors. However, measuring the sublethal and indirect effects of this active ingredient on nontarget organisms, such as lacewings, is important. Using morphological tools on target organs, we can evaluate these effects and use them as biomarkers for future ecotoxicological studies. Here, we investigated the effects of pyriproxyfen exposure on cocoon spinning and Malpighian tubules in Ceraeochrysa claveri adults. For this purpose, first-instar C. claveri larvae were orally exposed to Diatraea saccharalis egg clusters treated with pyriproxyfen in a solution of 50 or 100 mg a.i. L-1 throughout the larval stage. Insecticide exposure decreases predator survival, mainly in the prepupal and pupal stages, along with changes in the internal and external surfaces and thickness of the cocoon wall. Histopathological and ultrastructural injuries, including cytoplasmic vacuolization, loss of microvilli and a reduction in neutral glycoconjugates, were observed in Malphigian tubule cells of adults (≤24 h old). These changes indicate toxicological effects on Malpighian tubules that in lacewing involve cocoon spinning during metamorphosis and, in the adult stage, act in physiological processes of excretion and osmoregulation. Furthermore, it can affect the efficiency of the cocoon in protecting the specimen during metamorphosis against natural enemies and environmental factors. This organ has demonstrated its applicability as a biomarker for assessing the multisystemic effects of insecticides, thereby assisting in future risk assessments aimed at conserving nontargeted specimens.

Testing the Effects of Prey Type on the Life History and Population-Level Parameters of Chrysoperla externa (Neuroptera: Chrysopidae)

Green lacewings are valuable predators, utilized in augmentative biological control against various agricultural pests. However, further studies are required to comprehend the performance of these predators when consuming natural prey. We investigated the capacity of Chrysoperla externa (Hagen) to utilize the following three distinct prey types: the pupae of the coffee leaf miner Leucoptera coffeella (Guérin-Mèneville & Perrottet), the eggs of the sugarcane borer Diatraea saccharalis (F.), and the eggs of the Mediterranean flour moth Ephestia kuehniella (Zeller). The first two of these species are naturally occurring prey found in field crops, while the last serves as a factitious prey species for the mass rearing of natural enemies. We hypothesized that the type of prey would differentially affect the life history and population-level parameters of C. externa. Laboratory experiments were conducted to compare the pre-imaginal survival and developmental times, adult longevity and reproduction, and population growth of C. externa when larvae were provided with each of the three prey items. Results indicated that C. externa utilized the two natural prey items, L. coffeella pupae and D. saccharalis eggs, for its development, reproduction, and population growth. However, larvae developed significantly faster and females exhibited higher reproductive parameters, including fecundity and daily oviposition, when consuming the factitious prey, E. kuehniella eggs. This resulted in a higher intrinsic rate of population increase, as well as shorter times for the population to double in size. Understanding the population dynamics of C. externa when consuming different prey items is crucial for optimizing their utilization in augmentative biological control programs.