Biological Control Of Insects Research Articles

Persistence of Biological Control Agents in Waterhyacinth Following Herbicide Application

In Florida, waterhyacinth (Pontederia [Eichhornia] crassipes) (Martius) Solms Laubach (Pontederiaceae) is primarily controlled by herbicides, but overall control is enhanced by insect biological control agents that decrease growth and reproduction and slow regrowth. However, herbicide applications often disrupt the biological control agent populations when applied indiscriminately. Previous studies identified the utility of preserving populations of biological control agents in the vicinity of herbicide treated areas by establishing refuges for the insects. The objectives of this experiment were to quantify the impact of insect refuges, using groups of untreated P. crassipes within treated mats, on the regrowth of the new mat and the ability of biological control agents to persist following an herbicide treatment. Pontederia crassipes mats were grown with and without biological control agents, then treated with 2 concentrations of the herbicide penoxsulam. Plant growth metrics and biological control agent densities were monitored pre- and post-treatment and compared using ANCOVAs and non-parametric Kruskal-Wallis tests. Although the systemic activity of penoxsulam in the water column prevented the establishment of refuges in this study, biological control agent populations persisted following herbicide applications without additional releases and were able to remain at field densities after the decay and loss of P. crassipes. The treatment with no biological control agents and only half-label rate herbicide grew more densely, had greater dry weight biomass, higher relative growth rate, and produced more inflorescences than the plants in treatments with biological control agents. The half-label herbicide and biological control agent treatment performed as well as both treatments with label rate herbicide, and with and without biological control agents, respectively, in lowering P. crassipes density, final dry weight biomass, and relative growth rate. Although the concept of refuge systems at operational field scales requires further study, demonstrating the ability of biological control agents to persist even on sprayed mats is a necessary first step in determining the temporal and spatial factors that might influence the utility of such refuges.

In Vitro Effects of Streptomyces tyrosinase on the Egg and Adult Worm of Toxocara vitulorum

Several species of streptomycetes, saprophytic bacteria found widely distributed in soil, water and plants, produce bioactive compounds such as intra and extracellular hydrolases including lytic enzymes which reflecting on their importance in the biological control of insects and parasites. This study assessed the in vitro effects of Streptomyces tyrosinase, produced from Streptomyces spp. isolated from Egyptian soil, on animal-parasitic nematode Toxocara vitulorum, in terms of egg development and adult worm's cuticular structure, and as an alternative strategy to alleviate this infection. This study was conducted at the National Research Centre, Egypt in 2018. Five different concentrations of tyrosinase, ranged from 1%-30% were tested against the development of T. vitulorum eggs. The concentration induced the highest inhibitory activity was tested against adult T. vitulorum cuticle, which is essential for the protective and nutritive functions. The results were compared with those observed in the egg development and worm cuticle following incubation in Streptomyces protease (as a reference enzyme). Compared to Streptomyces protease, higher inhibitory activity on T. vitulorum egg development and extreme cuticular alterations of the treated adult worms had been observed following 24 h exposure to Streptomyces tyrosinase. Once the cuticle had been damaged, the enzyme would be able to penetrate deeper into the internal tissues of the nematode and caused more widespread disruption. The current study could offer a promising bio-control agent, Streptomyces tyrosinase, against T. vitulorum alternative to the more expensive synthetic anthelmintics.

Interactions between Entomopathogenic Fungi and Entomophagous Insects

Direct treatment of predators with entomopathogenic fungi (EPF) at different concentrations revealed that some species, like Beauveria bassiana and Metarhizium anisopliae, were found to have detrimental effects on all developmental stages of some predator species. Other species, like Numoraea rileyi and Paecilomycis fumosorosius, showed little or no effect on treated predators. Adult predators were found to avoid feeding on fungi-infected prey. EPF could be isolated from hibernating or field-collected coccinellids. Some studies indicated that combining a fungus with a predator could increase the rate of insect control in the field. As for parasitoids, this review indicates that the developmental stages of the egg parasitoids can develop successfully in host eggs treated with fungi. However, fungus-infected hosts negatively impact the development of larval parasitoids inside such hosts and this impact depends on the species and concentration of the fungus as well as the time between infection and parasitism. Some parasitoid females can discriminate between fungus-infected and uninfected hosts and do not parasitize the infected hosts. With appropriate timing, the parasitoids or predators could be combined with fungi for the biological control of insects in the field.

AKTIVITAS LARVISIDAL EKSTRAK ETIL ASETAT DAN HEKSANA DARI FILTRAT Beauveria bassiana TERHADAP Aedes aegypti

Beauveria bassiana produces several metabolites that are toxic to insects so that it can be used as a biological insect control agent as an alternative to synthetic pesticides. The aim of this study was to determine the larvicidal activity of ethyl acetate and hexane extract from B. bassiana filtrate culture against Aedes aegypti 2nd instar larvae. This research was it cooked by determining the optimum age of spore inoculum of B. bassiana on the Potato Dextrose Agar (PDA) based on the number of spores and its viability. Afterwards, we determine the incubation time of B. bassiana in the Potato Dextrose Broth (PDB) in order to obtain filtrate culture which have highest mortality effects against Ae. aegypti 2nd instar larvae. B. bassiana filtrate culture was extracted with hexane and ethyl acetate and tested aegypti for larvicidal activity with a concentration range of 50, 100, 200, 300 ppm. The LC50 value was carried out by probit analysis. The results showed that ninth day old culture in the PDA was the optimum age of spore inoculum with the spore number and viability were 2.54 x 107 spore/mL and 93.46% respectively. The filtrate of sixth day old culture in PDB medium gave 100% mortality against 2nd instar Ae. Aegypti larvae. LC50 values of ethyl acetate and hexane extract were 117.28 dan 287.09 ppm. These results showed that the ethyl acetate and hexane extract of B. bassiana filtrate culture have biopesticide potential against 2nd instar Ae. aegypti larvae.

A Review of Interactions between Insect Biological Control Agents and Semiochemicals.

Biological control agents and semiochemicals have become essential parts of the integrated pest management of insect pests over recent years, as the incorporation of semiochemicals with natural enemies and entomopathogenic microbials has gained significance. The potential of insect pheromones to attract natural enemies has mainly been established under laboratory conditions, while semiochemicals from plants have been used to attract and retain natural enemies in field conditions using strategies such as trap crops and the push–pull mechanism. The best-known semiochemicals are those used for parasitoids–insect pest–plant host systems. Semiochemicals can also aid in the successful dispersal of entomopathogenic microbials. The use of semiochemicals to disseminate microbial pathogens is still at the initial stage, especially for bacterial and viral entomopathogens. Future studies should focus on the integration of semiochemicals into management strategies for insects, for which several semiochemical compounds have already been studied. More effective formulations of microbial agents, such as granular formulations of entomopathogenic fungi (EPFs), along with bio-degradable trap materials, could improve this strategy. Furthermore, more studies to evaluate species-specific tactics may be needed, especially where more than one key pest is present.

Cassava mealybug biological control delivers multi-faceted societal benefits

As core component of sustainable intensification, biological control constitutes a tailor-made solution for the long-term management of both endemic and invasive pests. Here, drawing upon the example of the cassava mealybug ( Phenacoccus manihoti ; Hemiptera), we illuminate the myriad benefits of insect biological control. In 2008, the above mealybug invaded Asia, where it inflicted a 27% drop in aggregate cassava production and triggered a 260% surge in starch prices. Mealybug-induced shocks in Thailand's cassava output were offset by a 300,000-ha expansion of the agricultural frontier–accompanied with major loss of intact tropical forest. Mealybug outbreaks were permanently resolved through the release of the neotropical wasp Anagyrus lopezi (Hymenoptera). This minute parasitoid effectively suppressed P. manihoti at a continent-wide scale, restored food security, and delivered pest control services worth US$ 200–700/ha. This same parasitic wasp had previously averted famine for ∼ 20 million people in Africa. Our work emphasizes how beneficial (pest-controlling) insects help meet food production needs while benefiting farmers’ pockets, global commodity trade, and the environment.

New Genera and Species of Gelechiinae (Lepidoptera: Gelechiidae) from South America Feeding on Brazilian Peppertree

Recent efforts to discover insect biological control agents of the Brazilian peppertree, Schinus terebinthifolius (Anacardiaceae), include three new genera: Tentamen Metz, new genus, Longistrebula Metz, new genus, and Tectosquamae Metz, new genus; and three new species: Tentamen atrivirgulatum Metz, new species, Longistrebula argalata Metz, new species, and Tectosquamae furvalata Metz, new species, belonging to the subfamily Gelechiinae. Two additional new species, Tectosquamae poguei Metz, new species and Tectosquamae solisae Metz, new species, from Paraguay are also described. We diagnose, describe, and illustrate the new taxa, and propose hypotheses for placement within the subfamily.

Environment and host plant quality interact to determine the pupation success of a biological control agent, Agasicles hygrophila, on a nontarget host, Alternanthera sessilis

Understanding insect performance on nontarget native plants is critical in the risk assessment of weed biological control agents. A combination of laboratory and field host tests could help us better understand how abiotic and biotic environments interact to determine insect feeding and development on potential nontarget plants. In this study, we examined the performance of Agasicles hygrophila Selman and Vogt, a beetle used for biological control of the invasive plant alligator weed, Alternanthera philoxeroides (Mart.) Griseb., on a nontarget native plant, Alternanthera sessilis (L.) R.Br. ex DC. Our laboratory tests with various sized A. sessilis stems showed that larvae could pupate and successfully develop into adults on A. sessilis regardless of the stem size, but with larger stems improving the pupation rate. The insect was also found to pupate, and the pupae survive, when there was no stem available under laboratory conditions. When rearing pupae in a Petri dish, increased moisture improved pupal and adult survival, while most pupae were unable to develop to adults under dry conditions. In our field surveys, however, pupae were only found in stems, and no pupae appeared to survive without stems. Our predation tests further showed that pupae exposed to ambient environments (with no stems) had the lowest emergence rate, relative to pupae developing in A. sessilis stems. Together, these results indicate that A. sessilis stems facilitate pupal survival by providing moisture and protecting pupae from attack by natural enemies, explaining the difference in pupation rates between laboratory tests and field observations. Our study provides strong evidence that successful pupation of A. hygrophila on A. sessilis in nature is jointly determined by the environment and the host plant quality. Thus, considering abiotic and biotic factors that influence plant quality, insect survival and development could help to improve the assessment of the ecological host range of the insect biological control agent.

Protopolybia Exigua (Hymenoptera: Vespidae) Nesting on Citrus Grandis (Rutaceae)

Social wasps are predators. Two nests of Protopolybia exigua (Saussure) (Hymenoptera: Vespidae) were collected on pomelo (Citrus grandis [L.]) (Rutaceae) leaves, 1 active and another abandoned. The colonies of P. exigua were located under pomelo leaves, providing protection against adverse environmental conditions. The active nest had 12 pedicels, 600 brood cells, and 15 adult wasps. The knowledge of nesting habits of wasps in agroecosystems favors the management of these insects for biological control.

A New Genus and Species of Gelechiini (Lepidoptera: Gelechiidae) Feeding on Brazilian Peppertree

Recent efforts to discover insect biological control agents of the Brazilian peppertree, Schinus terebinthifolius (Anacardiaceae), include a new species belonging to a new genus, Spes schinella Metz, new genus, new species. We propose a hypothesis for placement of the new species among known Gelechiinae using the barcoding region of COI and targeted taxon sampling in a tree parsimony analysis, and discuss additional diagnostic morphological features for tribal placement. The new species is diagnosed, described, and illustrated.

Biological control of an agricultural pest protects tropical forests

Though often perceived as an environmentally-risky practice, biological control of invasive species can restore crop yields, ease land pressure and thus contribute to forest conservation. Here, we show how biological control against the mealybug Phenacoccus manihoti (Hemiptera) slows deforestation across Southeast Asia. In Thailand, this newly-arrived mealybug caused an 18% decline in cassava yields over 2009–2010 and an escalation in prices of cassava products. This spurred an expansion of cassava cropping in neighboring countries from 713,000 ha in 2009 to > 1 million ha by 2011: satellite imagery reveals 388%, 330%, 185% and 608% increases in peak deforestation rates in Cambodia, Lao PDR, Myanmar and Vietnam focused in cassava crop expansion areas. Following release of the host-specific parasitoid Anagyrus lopezi (Hymenoptera) in 2010, mealybug outbreaks were reduced, cropping area contracted and deforestation slowed by 31–95% in individual countries. Hence, when judiciously implemented, insect biological control can deliver substantial environmental benefits.

Unravelling the status of partially identified insect biological control agents introduced to control insects: an analysis of BIOCAT2010

The BIOCAT2010 (corrected) database of introductions of insects used as classical biological control agents (BCAs) against insects was analysed to recognise those introductions which involved a partially identified BCA, e.g. named to genus or family, but not to species. Quality controls made on a selection of these checked whether new taxonomic information in the literature had been missed from the database and this was found to be infrequent. Of 6227 BCA introductions since the 19th century, 686 (11.0%) were not identified to species level, and 74 were only identified to family or order level. Patterns by taxonomic group and countries making the introductions and the overall trend over time are presented. Since the 1990s, partially identified BCAs have been hardly used. Steps to ensure that partially identified BCAs can be identified in future are set out, and suggestions made regarding the scope for retroactive studies to recognise and name partially identified BCAs.

Population dynamics and overwintering of a biological control beetle, Agasicles hygrophila, on a nontarget plant Alternanthera sessilis, along a latitudinal gradient

Assessing the impact of temperature changes on insect population and overwintering on nontarget hosts is important for prediction of nontarget effects in weed biological control. Agasicles hygrophila is a beetle used for biological control of the invasive plant alligator weed, Alternanthera philoxeroides, with nontarget damage to a native plant, Alternanthera sessilis. In this study, we monitored plant growth and phenology along with beetle population and overwintering on these two hosts along a latitudinal gradient from subtropical to temperate climates (Guilin, Wuhan and Kaifeng) in China. We found only annual A. sessilis seedlings in temperate Kaifeng, but both annual seedlings and perennial ramets of A. sessilis were found in Guilin and Wuhan. However, in winter, living A. sessilis plants were found in only subtropical Guilin. Beetles at the Guilin site could successfully maintain their populations and overwinter on A. sessilis. Although the beetle could sustain its populations on A. sessilis at the other two higher-latitude sites during the growing season, it failed to overwinter on either species, indicating that the temperatures in different climate zones may directly and/or indirectly affect the development of insect biological control agents and their population sizes on nontarget hosts. Therefore, it is important to consider the shifting plant–insect interactions induced by climate when assessing potential nontarget effects of species introduced as biological control agents.

MASS REARING OF THE GREATER WAX MOTH, Galleria mellonella L.

This study was conducted to investigate the suitability of three suggested artificial diets prepared for mass rearing of the greater wax moth, Galleria mellonella L. to meet with the higher demand for mass multiplication of entomopathogenic nematodes as well as many parasitoids for insect biological control purposes. The suggested diets were compared to the natural food (i.e. honey bee wax) under laboratory conditions. The effect of such feeding on some biological aspects of eggs, larvae, pupae and adults of G. mellonella was studied. Summarized results revealed diet D3 (4 parts scratched bee wax and 1 part bee collected clover pollen) proved the best followed by natural (control) feeding. The superiority of diet D3 was represented by: shortened larval duration, induced significantly larval survival (88.33%) and weight (186 mg/mature larva) and pupal weight, minimized pupal mortality (6.7%), induced female moth fecundity (1056.6 eggs per female) and egg fertility and hatchability (97.81%).

The Xenon Test Chamber Q-SUN® for testing realistic tolerances of fungi exposed to simulated full spectrum solar radiation

The low survival of insect-pathogenic fungi when used for insect control in agriculture is mainly due to the deleterious effects of ultraviolet radiation and heat from solar irradiation. In this study, conidia of 15 species of entomopathogenic fungi were exposed to simulated full-spectrum solar radiation emitted by a Xenon Test Chamber Q-SUN XE-3-HC 340S (Q-LAB® Corporation, Westlake, OH, USA), which very closely simulates full-spectrum solar radiation. A dendrogram obtained from cluster analyses, based on lethal time 50 % and 90 % calculated by Probit analyses, separated the fungi into three clusters: cluster 3 contains species with highest tolerance to simulated full-spectrum solar radiation, included Metarhizium acridum, Cladosporium herbarum, and Trichothecium roseum with LT50 > 200 min irradiation. Cluster 2 contains eight species with moderate UV tolerance: Aschersonia aleyrodis, Isaria fumosorosea, Mariannaea pruinosa, Metarhizium anisopliae, Metarhizium brunneum, Metarhizium robertsii, Simplicillium lanosoniveum, and Torrubiella homopterorum with LT50 between 120 and 150 min irradiation. The four species in cluster 1 had the lowest UV tolerance: Lecanicillium aphanocladii, Beauveria bassiana, Tolypocladium cylindrosporum, and Tolypocladium inflatum with LT50 < 120 min irradiation. The QSUN Xenon Test Chamber XE3 is often used by the pharmaceutical and automotive industry to test light stability and weathering, respectively, but it was never used to evaluate fungal tolerance to full-spectrum solar radiation before. We conclude that the equipment provided an excellent tool for testing realistic tolerances of fungi to full-spectrum solar radiation of microbial agents for insect biological control in agriculture.

Are we losing sight of insect biological control in cyberspace?

Are we losing sight of insect biological control in cyberspace?

Plant sex effects on insect herbivores and biological control in a Short Rotation Coppice willow

In the wild, plant sex can affect plant-herbivore interactions and higher trophic levels, including natural enemies of the herbivores. However, the possibility of manipulating plant sex to improve biological control and reduce herbivory in domesticated dioecious crops remains unexplored. The dioecious bioenergy crop, Salix viminalis, is often planted in monoclonal, and thus monosexual, fields. We investigated whether using plant clones of either sex, or mixing plants of both sexes, reduced the performance and abundance of the herbivorous pest insect Phratora vulgatissima and its main natural enemy, Anthocoris nemorum, and whether predation was affected. The herbivore laid more eggs, and the predator survived longer, on female plants in the lab. However, these effects did not translate into differences in predation rates in laboratory experiments or differential insect abundances on plants of either sex or plantation sex composition in the field. Plant genotype did have a significant effect on insect abundances, but this was due to plant traits other than sex. The results indicate that manipulating plant sex will not lead to improved biological control or reduced insect herbivory in S. viminalis energy forestry, but suggest that a focus on plant genotypic differences offers promise for improving management practices.

Biological control of insect pests in Puerto Rico

The first documented observation on biological control of insects in Puerto Rico was made by botanist Andres Pedro Ledrú who arrived on the island in 1797 with a commission of French scientists. Much later (1880- 1887), Johannes Gundlach classified braconid wasps of the genus Conura. In 1895, Fernando López-Tuero published a treatise on sugarcane and the beneficial effects of Apanteles sp. and Euplectrus sp., two natural enemies of the sugarcane borer Diatraea saccharalis F. Since then more than 75 natural enemies were introduced, some very effective like the toad Bufo marinus L. in controlling white grubs in sugarcane, and others partially effective like the coffee leafminer parasitoid, Mirax insularis Muesebeck. Also, natural enemies were exported from Puerto Rico to other countries as far away as Mauritania. However, with the advent of chlorinated insecticides derived from DDT, in the early 1950s, the work on biocontrol declined dramatically, and not until the mid-1980s was biological control again considered a remedy to the problem of pests. In Puerto Rico, research was focused more on recognizing the endemic fauna of natural enemies and the introduction of parasitoids/predators. This paper presents a historical review and discussion of trends and approaches to the biological control of pests from its beginnings to the present.

Evolution of biological control agents following introduction to new environments

The introduction of biological control agents (BCAs) creates the potential for adaptive evolution in translocated organisms. BCAs are confronted with new environments that can promote adaptation to exploit novel resources, even within short ecological time frames. In particular, insect BCAs are amenable to rapid evolution due to their short generation times and relatively large population sizes. These factors hypothetically increase the likelihood that, when exposed to novel habitats, environmental selection could cause BCAs to extend their range to non-target host species. Alternatively, insects may simply extend their range as their generalist or polyphagous habits are fully realized. In this review, we consider recent literature that addresses these topics. Adaptations to environmental conditions have been demonstrated in a number of BCAs. Mechanisms of adaptation include founder effects, hybridization, and endosymbiosis. Yet, there is little evidence of adaptive host range expansions among insect and weed biological control agents to non-target species, albeit existing examples are from limited numbers of studies. Important future directions and current developments in the field incorporate next generation sequencing technology that can promote better resolution of population divergence, possible mechanisms involved in adaptation to novel resources, and insect hybridization. Future studies should also include a careful consideration of the influence of microbes on BCA efficacy and environmental adaptation.

Response of maize stemborers and associated parasitoids to the spread of grasses in the rainforest zone ofKisangani,DR Congo: effect on stemborers biological control

AbstractThe challenge with respect to nourishing the human population should be met in the context of global environmental change. Land‐use change has the potential to affect insect pest–natural enemy interactions.In theDemocraticRepublic ofCongo, the rainforest zone is subjected to intense anthropogenic disturbances that lead to the spread of habitats with a higher proportion of grasses in the landscape. Such a land‐use change raises the question of its effects on the biological control of insect pests.The proximity of varying vegetation types around agroecosystems is expected to influence species fitting differently and hence the population dynamics of insect pests and their biological control.Thus, the response of maize stemborers and their parasitoids to the spread of habitats with a higher proportion of grasses was assessed along an anthropogenic disturbance gradient in the rainforest zone ofKisangani,DemocraticRepublic ofCongo.The present study identified a decreased density of stemborers and infestation rates on maize as a result of an increased larval/pupal parasitism in wild habitats as the amount of grasses increased in the landscape. This effect was attributed to an increased parasitoid diversity subsequent to the settlement of an abundant and diverse stemborer community in wild habitats.