Prey Suitability of Galerucella pusilla Eggs for Two Generalist Predators, Coleomegilla maculata and Chrysoperla carnea

2002 ◽  
Vol 23 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Amy P. Wiebe ◽  
John J. Obrycki
Ecotoxicology ◽  
2017 ◽  
Vol 26 (5) ◽  
pp. 589-599 ◽  
Author(s):  
Paulo R. R. Barbosa ◽  
J. P. Michaud ◽  
Clint L. Bain ◽  
Jorge B. Torres

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Matthias Schöller

The egg case ofCryptocephalus rufipes(Goeze) is described and illustrated. In laboratory trials, eggs of field-collectedC. rufipeswere observed for larval emergence (untreated control) or exposed to two species of generalist predators,Chrysoperla carnea(Stephens) orXylocoris flavipes(Reuter) in no-choice experiments. The behaviour of the predators upon contact with theC. rufipeseggs was observed. The number of hatching larvae was counted and compared. In the presence of each of the two species of predators, larval emergence was significantly reduced. Eggs that were not protected by an egg case were completely consumed by the predators.C. rufipeseggs were therefore incompletely protected from the studied generalist predators. This is the first study showing experimentally the protective function of cryptocephaline egg case.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Heidi L. Kolkert ◽  
Rhiannon Smith ◽  
Romina Rader ◽  
Nick Reid

AbstractFactors influencing the efficacy of insectivorous vertebrates in providing natural pest control services inside crops at increasing distances from the crop edge are poorly understood. We investigated the identity of vertebrate predators (birds and bats) and removal of sentinel prey (mealworms and beetles) from experimental feeding trays in cotton crops using prey removal trials, camera traps and observations. More prey was removed during the day than at night, but prey removal was variable at the crop edge and dependent on the month (reflecting crop growth and cover) and time of day. Overall, the predation of mealworms and beetles was 1-times and 13-times greater during the day than night, respectively, with predation on mealworms 3–5 times greater during the day than night at the crop edge compared to 95 m inside the crop. Camera traps identified many insectivorous birds and bats over crops near the feeding trays, but there was no evidence of bats or small passerines removing experimental prey. A predation gradient from the crop edge was evident, but only in some months. This corresponded to the foraging preferences of open-space generalist predators (magpies) in low crop cover versus the shrubby habitat preferred by small passerines, likely facilitating foraging away from the crop edge later in the season. Our results are in line with Optimal Foraging Theory and suggest that predators trade-off foraging behaviour with predation risk at different distances from the crop edge and levels of crop cover. Understanding the optimal farm configuration to support insectivorous bird and bat populations can assist farmers to make informed decisions regarding in-crop natural pest control and maximise the predation services provided by farm biodiversity.


1989 ◽  
Vol 121 (4-5) ◽  
pp. 309-314 ◽  
Author(s):  
Elmer A.C. Hagley

AbstractRelease of the chrysopid, Chrysoperla cornea Stephens, at a rate of ca. 335 000 eggs per hectare, reduced significantly the numbers of apterous adults and nymphs of the green apple aphid, Aphis pomi DeGeer, on dwarf apple trees. Greater reduction in aphid numbers occurred in 1984 than in 1985, and the efficiency of the predator might have been influenced by the predator:prey ratios (1:10 and 1:19) used and by the mean daily temperature that occurred during the test periods. Application of azinphosmethyl (Guthion 50% wp, 0.105 and 0.075 kg AI/100 L) did not adversely affect predation of apterous A. pomi by larvae of C. carnea.


Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 583
Author(s):  
Carl C. Christensen ◽  
Robert H. Cowie ◽  
Norine W. Yeung ◽  
Kenneth A. Hayes

Classic biological control of pest non-marine mollusks has a long history of disastrous outcomes, and despite claims to the contrary, few advances have been made to ensure that contemporary biocontrol efforts targeting mollusks are safe and effective. For more than half a century, malacologists have warned of the dangers in applying practices developed in the field of insect biological control, where biocontrol agents are often highly host-specific, to the use of generalist predators and parasites against non-marine mollusk pests. Unfortunately, many of the lessons that should have been learned from these failed biocontrol programs have not been rigorously applied to contemporary efforts. Here, we briefly review the failures of past non-marine mollusk biocontrol efforts in the Pacific islands and their adverse environmental impacts that continue to reverberate across ecosystems. We highlight the fact that none of these past programs has ever been demonstrated to be effective against targeted species, and at least two (the snails Euglandina spp. and the flatworm Platydemus manokwari) are implicated in the extinction of hundreds of snail species endemic to Pacific islands. We also highlight other recent efforts, including the proposed use of sarcophagid flies and nematodes in the genus Phasmarhabditis, that clearly illustrate the false claims that past bad practices are not being repeated. We are not making the claim that biocontrol programs can never be safe and effective. Instead, we hope that in highlighting the need for robust controls, clear and measurable definitions of success, and a broader understanding of ecosystem level interactions within a rigorous scientific framework are all necessary before claims of success can be made by biocontrol advocates. Without such amendments to contemporary biocontrol programs, it will be impossible to avoid repeating the failures of non-marine mollusk biocontrol programs to date.


2021 ◽  
Vol 34 (4) ◽  
pp. 223-239
Author(s):  
Rosalind K. Humphreys ◽  
Graeme D. Ruxton ◽  
Alison J. Karley

AbstractDropping behavior is an effective antipredator defense utilized by many insects including aphids, which drop from plants to lower plant parts or underlying substrates to avoid attack from predatory invertebrates. While research commonly focusses on triggers of dropping, less attention is given to what happens to prey individuals following escape drops. In this study, the duration of tonic immobility, recovery rates, and cases of “instant recovery” (re-clinging to lower plant parts) exhibited by potato aphids (Macrosiphum euphorbiae) that dropped from potted seedlings in response to introduced ladybird (Adalia bipunctata) adults, lacewing (Chrysoperla carnea) larvae, and a standardized tactile stimulus were investigated in relation to a range of environmental factors. Air temperature had a negative correlation with the duration of post-dropping tonic immobility; as temperature increased, time spent motionless decreased. Aphids also showed a pattern of increased recovery rate at higher temperatures. Aphids may be selected to move off the substrate quicker to avoid risks of overheating/desiccation at higher temperatures; and/or higher body temperature facilitates locomotion. Stimulus type also influenced recovery rate back to the original seedling, with aphids generally recovering after the standardized stimulus quicker than after dropping triggered by a real predator. Considering cases of instant recovery onto lower-reaches of the host seedling, seedling height influenced the likelihood of re-clinging, with aphids that managed to instantly recover dropping from, on average, taller seedlings than aphids that dropped to the substrate. Plant architecture could mitigate the costs of dropping for aphids, but further studies quantifying understory foliage cover are needed.


Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 321
Author(s):  
Stefan Cristian Prazaru ◽  
Giulia Zanettin ◽  
Alberto Pozzebon ◽  
Paola Tirello ◽  
Francesco Toffoletto ◽  
...  

Outbreaks of the Nearctic leafhopper Erasmoneura vulnerata represent a threat to vinegrowers in Southern Europe, in particular in North-eastern Italy. The pest outbreaks are frequent in organic vineyards because insecticides labeled for organic viticulture show limited effectiveness towards leafhoppers. On the other hand, the naturally occurring predators and parasitoids of E. vulnerata in vineyards are often not able to keep leafhopper densities at acceptable levels for vine-growers. In this study, we evaluated the potential of two generalist, commercially available predators, Chrysoperla carnea and Orius majusculus, in suppressing E. vulnerata. Laboratory and semi-field experiments were carried out to evaluate both species’ predation capacity on E. vulnerata nymphs. The experiments were conducted on grapevine leaves inside Petri dishes (laboratory) and on potted and caged grapevines (semi-field); in both experiments, the leaves or potted plants were infested with E. vulnerata nymphs prior to predator releases. Both predator species exhibited a remarkable voracity and significantly reduced leafhopper densities in laboratory and semi-field experiments. Therefore, field studies were carried out over two growing seasons in two vineyards. We released 4 O. majusculus adults and 30 C. carnea larvae per m2 of canopy. Predator releases in vineyards reduced leafhopper densities by about 30% compared to the control plots. Results obtained in this study showed that the two predators have a potential to suppress the pest density, but more research is required to define appropriate predator–prey release ratios and release timing. Studies on intraguild interactions and competition with naturally occurring predators are also suggested.


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