Pollen Ingestion by Chrysoperla externa (Hagen) Adults in a Diversified Organic Agroecosystem

Pollens of Fabaceae and Poaceae Alone or Combined with Honey Solution? Suitable Diet for Adults of Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae)

The main source of proteins for adult Chrysoperla externa (Hagen) is pollen, the content of which varies among species and may have different effects on the adult biology. In the laboratory, we evaluated the suitability of pollens from Canavalia ensiformis (JB), Crotalaria juncea (SH) (both Fabaceae), Pennisetum glaucum (MI), Sorghum bicolor (SO), and Zea mays (CO) (all Poaceae), alone or as mixtures of pollen from one species of each family, for the performance of adult C. externa; these diets were compared to brewer's yeast + honey (standard diet), 50% honey solution and water alone. Excluding water, the diets were supplemented with an extra honey solution (EHS). The protein content was used as a measure of diet quality, although the carbon and mineral contents were also evaluated. The diets combined with EHS significantly improved adult longevity. All the pollen diets promoted egg production. The CO-alone, SO-alone, JB-alone, SH-alone, SO + JB, CO + SH, MI + SH and SO + SH mixtures resulted in reproduction rates similar to those observed with the standard diet, indicating their suitability for C. externa. In contrast, the effects of MI-alone, MI + JB and CO + JB on reproduction were significantly worse than those of the standard diet. In terms of nutritional value, SH was the pollen enriched in protein, CO, MI and SO were protein-poor pollens, and the JB and dipollen mixtures presented intermediate levels. In conclusion, in contrast to our expectations, a mixture of Fabaceae and Poaceae pollens generally is not nutritionally superior to each pollen alone for improving the performance of adult C. externa.

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.

Effects of Fabaceae and Poaceae Pollen Accessibility and Traits on the Pollinivory of Adult Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae)

Pollen is a food source for adult Chrysoperla externa (Hagen), whose larvae are biocontrol agents against pests. However, adults may face challenges in foraging for pollen due to differences in pollen accessibility and variability in pollen morphology and chemistry. In the laboratory, we investigated the ability of adult C. externa to consume pollen from flowers of Cajanus cajan, Canavalia ensiformis, Crotalaria juncea, Flemingia macrophylla, Avena strigosa, Pennisetum glaucum, Sorghum bicolor, and Zea mays, and we explored whether adults chose any of these pollens based on their quantitative and qualitative features. Cajanus cajan and F. macrophylla pollen were the only ones not consumed by adults when confined to flowers. Pollen removed from the preanthesis buds was offered simultaneously for 24 and 48 h. In both periods, adults consumed more of the medium-sized P. glaucum (with the second largest exine thickness) and large-sized Z. mays (with the thinnest exine) pollen, even though they had significantly less crude protein than Fabaceae pollen, whose sizes varied from medium (C. juncea, with the thickest exine) to large (C. ensiformis, whose exine thickness was equal to that of P. glaucum). Overall, adults consumed more Poaceae pollen than Fabaceae pollen, but the palynological features and the protein contents did not affect this choice. Our results highlighted that C. juncea, P. glaucum, S. bicolor and Z. mays are good pollen sources for adult C. externa and should be considered promising candidates in the selection of insectary plants to deploy in biocontrol programs aimed at the conservation of this lacewing.

Pollen and nectar have different effects on the development and reproduction of noctuid moths

Although many noctuid insects are agricultural pests that threaten food production, they are also the major nocturnal pollinators of flowering plants. Larval foods of noctuid pest insects have been well studied for developing control strategies, but knowledge on host plants for the adults is rather scarce. Here, the impact of plant-derived foods on adult survival, fecundity and reproductive physiology of four global species of noctuid pests (Mythimna separata Walker, Mythimna loreyi Duponchel, Athetis lepigone Möschler, and Hadula trifolii Hufnagel) was assessed in laboratory experiments. Our results indicated that nectar slowed testis decay and prolonged the oviposition period and lifespan, increasing fecundity. Acacia nectar increased the longevity of male and female adults by 3.2∼10.9 and 2.4∼5.0 days, respectively, and fecundity of females by 1.22∼3.34 times compared to water-fed individuals. The fitness among the different species of noctuid moths differed on specific pollen diets. On pine pollen, the fecundity of female moths of M. separata, A. lepigone and H. trifolii was 10.06, 33.52, and 28.61%, respectively, lower than those of the water-fed females, but the fecundity of female moths of M. loreyi on pine pollen was 2.11 times greater than for the water-fed individuals. This work provides valuable information on the nutritional ecology for noctuid moths, which can aid the development and design of nutritional attractants within noctuid pests-infected cropping systems and provide a basis for effective and targeted management of global noctuid pests.

Residual action of five insecticides on larvae and adults of the neotropical predators Chrysoperla externa (Neuroptera: Chrysopidae) and Eriopis connexa (Coleoptera: Coccinellidae)

This work aimed to evaluate the residual action of five insecticides on larvae and adults of the predators Chrysoperla externa (Hagen) and Eriopis connexa (Germar). The insecticides gamma-cyhalothrin, imidacloprid+beta-cyfluthrin, methomyl, thiamethoxam, and thiamethoxam+lambda-cyhalothrin were sprayed in pod bean plants until the point of runoff. Weekly, at 3, 10, 17, 24, and 31 days, first instar larvae and adults of both predators were exposed to leaves containing dry residues of the insecticides. Based on the mortality observed throughout the bioassays, the insecticides were classified according to the scale of the residual effects proposed by the International Organization for Biological and Integrated Control (IOBC). Except for thiamethoxam+lambda-cyhalothrin, which was moderately persistent (class 3) to larvae of C. externa and E. connexa, all other tested insecticides were persistent (class 4) to larvae of both species. Gamma-cyhalothrin, imidacloprid + beta-cyfluthrin, and methomyl were persistent (class 4) to C. externa adults, while thiamethoxam was moderately persistent (class 3) and thiamethoxam + lambda-cyhalothrin was slightly persistent (class 2) to the adult stage. As for E. connexa adults, imidacloprid + beta-cyfluthrin and methomyl were persistent (class 4) and gamma-cyhalothrin, thiamethoxam, and thiamethoxam + lambda-cyhalothrin were moderately persistent (class 3). Thus, due to extended residual effect, these insecticides must be avoided when larvae and adults of both predators are active in the crop.

Manipulation of Agricultural Habitats to Improve Conservation Biological Control in South America

Stable and diversified agroecosystems provide farmers with important ecosystem services, which are unfortunately being lost at an alarming rate under the current conventional agriculture framework. Nevertheless, this concern can be tackled by using ecological intensification as an alternative strategy to recuperate ecosystem services (e.g., biological control of pests). To this end, the manipulation of agricultural habitats to enhance natural enemy conservation has been widely explored and reported in Western Europe and North America, whereas in other parts of the world, the investigation of such topic is lagging behind (e.g., South America). In this forum, we gathered published and unpublished information on the different ecological habitat management strategies that have been implemented in South America and their effects on pest control. Additionally, we identify the various challenges and analyze the outlook for the science of conservation biological control in South America. More specifically, we reviewed how different agricultural practices and habitat manipulation in South America have influenced pest management through natural enemy conservation. The main habitat manipulations reported include plant diversification (intercropping, insectary plants, agroforestry), conservation and management of non-crop vegetation, and application of artificial foods. Overall, we noticed that there is a significant discrepancy in the amount of research on conservation biological control among South American countries, and we found that, although intercropping, polycultures, and crop rotation have been reported in agroecosystems since pre-Inca times, more systematic studies are required to evaluate the true effects of habitat management to implement conservation biological control for pest control in South America.