Odimar Zanuzo Zanardi

Lethal and Sublethal Impacts of Acaricides on Tamarixia radiata (Hemiptera: Eulophidae), an Important Ectoparasitoid of Diaphorina citri (Hemiptera: Liviidae)

ABSTRACT The use of synthetic acaricides for management of pest mites may alter the efficacy of the ectoparasitoid Tamarixia radiata (Waterston) in biological control of Diaphorina citri Kuwayama, the vector of the bacteria associated with huanglongbing (HLB) in citrus orchards.We evaluated the toxicity of 16 acaricides that are recommended for the control of citrus-pest mites to T. radiata. Acrinathrin, bifenthrin, carbosulfan, and fenpropathrin caused high acute toxicity and were considered harmful (mortality >77%) to T. radiata. Abamectin, diflubenzuron, etoxazole, fenbutatin oxide, fenpyroximate, flufenoxuron, hexythiazox, propargite, spirodiclofen, and sulfur caused low acute toxicity and affected the parasitism rate and emergence rate of adults (F1 generation), and were considered slightly harmful to T. radiata. Dicofol and pyridaben did not affect the survival and action of the ectoparasitoid, and were considered harmless. In addition to its acute toxicity, carbosulfan caused mortality higher than 25% for >30 d after application, and was considered persistent. Acrinathrin, bifenthrin, fenpropathrin, fenpyroximate, propargite, and sulfur caused mortalities over 25% until 24 d after application and were considered moderately persistent; abamectin was slightly persistent, and fenbutatin oxide was short lived. Our results suggest that most acaricides used to control pest mites in citrus affect the density and efficacy of T. radiata in the biological control of D. citri. However, further evaluations are needed in order to determine the effect of these products on this ectoparasitoid under field conditions.

Toxicities and Residual Effects of Toxic Baits Containing Spinosad or Malathion to Control the Adult Anastrepha fraterculus (Diptera: Tephritidae)

Abstract An important objective of Integrated Pest Management (IPM) is to reduce chemical contamination of the environment and food; for example by replacing broadcast sprays with selective toxic baits. The objective of the study was to evaluate the toxicity and residual effects of the a ready-for-use commercial bait Success* 0.02 CB®, which contains 0.24 g a.i. L-1 of spinosad, and to compare its performance to a few other formulations with spinosad and malathion mixed either in hydrolyzed corn protein (Biofruit® 3%) or in sugarcane molasses (7%) on adults Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) in the laboratory, greenhouse and field conditions. In the laboratory, formulations with spinosad caused mortality equivalent to malathion-based toxic baits 96 h after exposure of the insects, regardless of the attractive substance used. In the greenhouse, Success* 0.02 CB®, resulted in mortality of 81.9% of A. fraterculus adults 7 days after application of treatment; being significantly superior to either standard spinosad or malathion treatments (mortality between 44.1 to 62.1%) in the same evaluation period. In field, in the absence of rain, Success* 0.02 CB® and spinosad formulations with Biofruit® 3% or sugarcane molasses (7%) caused mortalities from 70.0 to 83.0% up to 7 DAT, not differing statistically from the malathion treatments (mortality of 100%) during this time. However, at 10 DAT only malathion formulations with Biofruit® 3% or sugarcane molasses (7%) substantial mortalities, i.e., 73.3% and 76.7%, respectively, which were superior to formulations with spinosad (mortality < 45%). However, at 14 DAT all tested formulations caused less than 40% mortality of A. fraterculus adults. One day after a rain (3.8 mm), the formulations with malathion caused mortalities between 56.7 and 81.8%, which were statistically superior to the formulations with spinosad (mortality < 20%). However, after the occurrence of an additional 0.4 mm of rain, all formulations caused mortality lower than 15%. Biofruit® 3% can be used as a replacement for sugarcane molasses (7%) in formulating toxic baits and Success* 0.02 CB® and other formulations with spinosad may be used to replace malathion to manage populations of A. fraterculus. In practical field operations, the effectiveness of toxic bait formulations may be extended by applying them to the lower canopy where they are partially protected from rain.

Are the Pupae and Eggs of the Lacewing Ceraeochrysa cubana (Neuroptera: Chrysopidae) Tolerant to Insecticides?

ABSTRACT The tolerance of Ceraeochrysa cubana (Hagen) pupae and eggs to 11 insecticides was evaluated under laboratory conditions, based on lethal and sublethal effects. Eggs at three ages (≤24-hold, 48- to 72-h-old, and 96- to 120-h-old) and pupae at ≤48-h-old were used. All the insecticides were considered harmless when applied at the pupal stage. Phosmet and pyriproxyfen insecticides were considered harmless to eggs irrespective of the age. Esfenvalerate was harmless to eggs at the ages of ≤24-h-old and 48- to 72-h-old. Imidacloprid SC and azadirachtin were harmless to eggs at ages of 48- to 72-h-old and 96- to 120-h-old, and thiamethoxam was only harmless to eggs at 96- to 120-h-old of age. In contrast, chlorpyrifos and malathion were harmful to eggs at the age of 96- to 120-h-old, and imidacloprid WG was slightly harmful to the three egg ages evaluated. Lambda-cyhalothrin + chlorantraniliprole and lambda-cyhalothrin + thiamethoxam were slightly and/or moderately harmful to all egg ages evaluated. Based on the life table parameters, the insecticides thiamethoxam, imidacloprid SC, phosmet, pyriproxyfen, and azadirachtin did not affect the net rate of reproduction (Ro) of C. cubana. Lambdacyhalothrin + chlorantraniliprole decreased the Ro and increased the population doubling time (Td) independently of the egg ages evaluated. Therefore, the insecticides pyriproxyfen and phosmet are compatible with eggs of the predator C. cubana, but other insecticides should be evaluated under field conditions to verify their effects on the predator.

Sublethal effects of pyrethroid and neonicotinoid insecticides on Iphiseiodes zuluagai Denmark and Muma (Mesostigmata: Phytoseiidae)

The predator mite Iphiseiodes zuluagai Denmark & Muma is an important biological-control agent of mite pests, and it is one of the most common species found in citrus orchards. This study assessed, under laboratory conditions, the toxicity and duration of the harmful effects of five insecticides, the three pyrethroids deltamethrin, esfenvalerate and lambda-cyhalothrin, and the two neonicotinoids imidacloprid and thiamethoxam on I. zuluagai. Furthermore, we estimated the life-table parameters of the predator. Our results showed that deltamethrin and lambda-cyhalothrin caused higher mortality of larvae and adults than imidacloprid and thiamethoxam. In contrast, esfenvalerate provided larval mortality similar to imidacloprid and thiamethoxam, but it did not cause significant adult mortality of the predator. Mites that developed on pyrethroid residues showed lower survival of the immature stages, fecundity, and longevity compared to neonicotinoid residues and the control treatment. The estimated life-table parameters indicated that deltamethrin, lambda-cyhalothrin and esfenvalerate caused greater reduction in Ro and r of I. zuluagai compared with imidacloprid and thiamethoxam, which were similar to the control treatment. Besides the impacts on biological and population parameters, the duration of the harmful activity of pyrethroid insecticides was longer than the neonicotinoids. Therefore, the use of pyrethroid insecticides to control pest insects may involve serious implications for integrated pest-management programs that aim to exploit the biological control by I. zuluagai in citrus orchards.

Development and reproduction of Panonychus citri (Prostigmata: Tetranychidae) on different species and varieties of citrus plants

The species and varieties of citrus plants that are currently grown can favor the population growth of the citrus red mite Panonychus citri (McGregor) (Prostigmata: Tetranychidae) and alter the pest management programs in citrus groves. In this study we evaluated, in the laboratory, the development and reproduction of P. citri and estimated its life table parameters when reared on four varieties of Citrus sinensis (L.) Osbeck (Valencia, Pera, Natal, and Hamlin), one variety of Citrus reticulata Blanco (Ponkan) and one variety of Citrus limon (L.) Burm. (Sicilian). The incubation period and egg viability were not affected by the host plant. However, the development and survival of the immature stage were significantly lower on Hamlin orange than on Valencia, Pera and Natal oranges, Ponkan mandarin and Sicilian lemon. The fecundity and oviposition period of females were lower on Hamlin orange than on the other hosts. Mites reared on Valencia orange and Sicilian lemon had a higher net reproductive rate (R0), intrinsic growth rate (r) and finite rate of increase (λ), and a shorter interval between generations (T) than on Pera, Natal and Hamlin oranges and Ponkan mandarin. On the other hand, mites reared on Hamlin orange had the lowest R0, r and λ and the highest T among the hosts. Based on the results obtained we recommend that for Valencia orange and Sicilian lemon, the mite monitoring programs should be more intense to detect the initial infestation of pest, avoiding the damage in plants and the increase in production costs.

Putative sex pheromone of the Asian citrus psyllid, Diaphorina citri, breaks down into an attractant

Under laboratory conditions, mating activity in Asian citrus psyllid (ACP) started 4 days after emergence, peaked at day 7, and showed a clear window of activity starting 8 h into the photophase and extending through the first hour of the scotophase. We confirmed that ACP males are attracted to emanations from conspecific females. Traps loaded with a candidate compound enriched with female extract, lignoceryl acetate (24Ac), at various doses were active only after being deployed for several weeks in the field, suggesting that a degradation product, not the test compound, was the active ingredient(s). Lignocerol, a possible product of 24Ac degradation, was not active, whereas acetic acid, another possible degradation product, was found in the airborne volatile collections from lures matured under field conditions and detected in higher amounts in volatiles collected from females at the peak of mating activity than in male samples. Acetic acid elicited dose-dependent electroantennographic responses and attracted ACP males, but not females, in Y-type and 4-way olfactometers. Field tests showed that acetic acid-baited traps captured significantly more males than control traps. Surprisingly, captures of females in acetic acid-baited traps were also higher than in control traps, possibly because of physical stimuli emitted by captured males.

The impact of six insecticides commonly used in control of agricultural pests on the generalist predator Hippodamia convergens (Coleoptera: Coccinellidae)

Hippodamia convergens is an important predator found in different agroecosystems. We evaluated the impacts of six insecticides on eggs, larvae and adults of this predator. For eggs, all insecticides reduced larval hatching rates, but did not affect egg duration. Chlorpyrifos and phosmet reduced larval survival; and chlorpyrifos, etofenprox and phosmet prolonged the larva development time. The survival and duration of pupae were not affected by all insecticides tested. Chlorpyrifos reduced fecundity, fertility and longevity when eggs were sprayed. For first-instar larvae, chlorpyrifos, etofenprox, phosmet and imidacloprid caused 100% mortality, while azadirachtin and thiamethoxam caused 35.0 and 52.7% mortality, respectively. However, azadirachtin and thiamethoxam did not affect the other biological parameters of the predator. In adults, chlorpyrifos, etofenprox and phosmet reduced adult survival. Chlorpyrifos, etofenprox, and phosmet reduced fecundity and longevity, but did not affect fertility. Azadirachtin, imidacloprid and thiamethoxam did not affect fecundity, fertility or longevity. Based on demographic parameters, all insecticides reduced the net reproductive rate (Ro), intrinsic rate of increase (r) and finite rate of increase (λ) of the predator when eggs were treated directly. Azadirachtin, chlorpyrifos, etofenprox and phosmet increased the mean generation time (T), while the effects of imidacloprid and thiamethoxam were similar to the control. When first-instar larvae were treated, azadirachtin and thiamethoxam reduced the Ro, r and λ. Thiamethoxam increased the T value, while the effects of the other insecticides were similar to the control. These insecticides should be used with caution, in order to reduce their harmful effects on the predator in agroecosystems.

Spraying pyrethroid and neonicotinoid insecticides can induce outbreaks of Panonychus citri (Trombidiformes: Tetranychidae) in citrus groves

Panonychus citri (McGregor) (Trombidiformes: Tetranychidae) is one of the main defoliator mites in citrus groves. In Brazil, P. citri was formerly considered a secondary pest, but in recent years, the population levels of this mite have increased in many groves, requiring additional acaricide applications for its control. The population growth of P. citri is associated with the increase in the number of applications of pyrethroid and neonicotinoid insecticides to control insect citrus pests. This study assessed the effects of pyrethroid (deltamethrin, esfenvalerate, λ-cyhalothrin) and neonicotinoid (imidacloprid and thiamethoxam) insecticides on biological, behavioral and demographic parameters of P. citri. None of the insecticides tested affected larval hatching, but deltamethrin, esfenvalerate, and λ-cyhalothrin reduced the survival of larvae and protonymphs. Deltamethrin, esfenvalerate, and λ-cyhalothrin induced a significant increase in the fecundity of surviving females. Pyrethroids also caused repellency and changed feeding and oviposition preferences. In contrast, imidacloprid and thiamethoxam did not affect the survival of immature stages, but imidacloprid significantly increased fecundity. Imidacloprid and thiamethoxam did not cause any repellent effect or changes in the feeding and oviposition preferences. Based on the demographic parameters, deltamethrin, λ-cyhalothrin, and imidacloprid increased Ro, r, and λ, whereas esfenvalerate and thiamethoxam were similar to the control. Therefore, the use of these insecticides (especially deltamethrin, λ-cyhalothrin, and imidacloprid) requires caution, such as avoiding repeated use of these compounds during the periods of P. citri incidence in citrus groves.