Hellenic Plant Protection Journal 7: 43-51, 2014

Hellenic Plant Protection Journal 7: 43-51, 2014 Toxicity assessment of insecticides to nymphs and adults of Calliptamus barbarus barbarus Costa (Orthoptera: Acrididae) S.A. Antonatos1,2* and N.G. Emmanouel2 Summary The toxicity of various insecticides to nymphs and adults of Calliptamus barbarus barbarus (Orthoptera: Acrididae) was studied in laboratory bioassays. The insecticides used were imidacloprid, spinosad, alpha cypermethrin, lambda cyhalothrin, difl ubenzuron and azadirachtin. Lambda cyhalothrin was used only in bioassays with adult grasshoppers whereas difl ubenzuron and azadirachtin were used only in bioassays with grasshopper nymphs. The insecticide with the most toxic eff ect on nymphs and adults of C. barbarus barbarus was spinosad followed by imidacloprid and alpha cypermethrin. Ten days after treatment the mortalities obtained from those three insecticides were 98.5%, 89.1% and 81.3% in nymphs and 98.4%, 71.9% and 67.2% in adults, respectively. The toxicity of lambda cyhalothrin to the grasshopper adults was moderate, reaching 43.8% mortality ten days after their exposure. Difl ubenzuron and azadirachtin provided moderate and reduced level of mortality, respectively, to the grasshopper nymphs. The mortalities obtained from these insecticides ten days after treatment were 53.1% and 29.7%, respectively. The same pattern was observed for the lethal time with spinosad having the most rapid action. Additional keywords: grasshoppers, insecticides, lethal time, toxic eff ect Introduction various crops by these grasshoppers result- ed in the declaration of large areas under a Several grasshopper species of Calliptamus special regime by the state where sprayings are widely distributed throughout the coun- with insecticides were conducted. This re- tries of the Mediterranean basin (Larrosa et sults in an increased cost of crop production al., 2008; Wilps et al., 2002; Merton, 1959) and can create serious ecological problems. and damages on crops have often been re- In high population densities, grasshop- ported (Aragón et al., 2013). Calliptamus bar- pers consume large amounts of plant mass barus barbarus (Costa, 1836) along with the (Weiland et al., 2002; Antonatos et al., 2013). closely related species Calliptamus italicus Additionally, they often cut plant parts with- (Linnaeus, 1758) are very common in Greece out consuming them (Holmberg and Hard- (Willemse, 1984). They are highly polyphago- man, 1984) and contaminate with their bod- us and they can feed on a broad spectrum of ies and faecal material the harvested crops plants belonging to the families Asteraceae, (Amarasekare and Edelson, 2004). Numer- Papilionaceae, Malvaceae, Poaceae, Fabace- ous insect predators of orthopterans, which ae, Solanaceae, Brassicaceae as well as on may be useful in grasshoppers’ control, have many fruit trees (Bei-Bienco and Mishchen- been reported in old studies (Merton, 1959; ko, 1963). In many cases, heavy attack on Dempster, 1957), however control of grass- hopers nowadays depends mainly on appli- cation of insecticides. 1 Department of Entomology and Agricultural Zoolo- Several insecticides (organochlorine, or- gy, Benaki Phytopathological Institute, 8 St. Delta Str., GR-145 61 Kifi ssia, Attica, Greece ganophosphate or carbamate) have been 2 Laboratory of Agricultural Zoology and Entomolo- used successfully for the chemical control of gy, Agricultural University of Athens, 75 Iera odos Str., GR-118 55 Athens, Greece grasshoppers (Tharp et al., 2000; Weiland et * Corresponding author: [email protected] al., 2002) but due to change in pesticide reg- © Benaki Phytopathological Institute 44 Antonatos & Emmanouel ulations in the European Union the use of Insecticides most of those has already been banned. The insecticides that were used in bioas- In recent years most of the research con- says with C. barbarus barbarus were imida- cerning the chemical control of orthopter- cloprid 35% w/v (SC), alpha cypermethrin ans involves the use of pyrethroids (Ama- 10% w/v (EC) and spinosad 48% w/v (SC) for rasekare and Edelson, 2004; Reinert et al., both nymphs and adults. Two IGRs difl uben- 2001; Johnson, 1990; Olaifa, 1986; Ewen et zuron 25% w/w (WP) and azadirachtin 1% al., 1984; Mukeri and Ewen, 1984), neonico- w/v (EC) were tested on nymphs and lamb- tinoids (Wilps et al., 2002; Tharp et al., 2000), da cyhalothrin 9.43% w/w (CS) tested on spinosins (Amarasekare and Edelson, 2004), adults. The doses of the insecticides used in insect growth regulators (IGRs) (Weiland et the experiments were for imidacloprid 7.7gr al., 2002; Amarasekare and Edelson, 2004) a.i./100lt water, for alpha cypermethrin 4gr and entomopathogenic organisms (Frank, a.i./100lt water, for lambda cyhalothrin 1.2gr 2009; Amarasekare and Edelson, 2004; Sie- a.i./100lt water, for spinosad 16.8gr a.i./100lt glaff et al., 1998; Milner et al., 1994; Moore et water, for difl ubenzuron 25gr a.i./100lt wa- al., 1992; Johnson and Pavlikova, 1986). ter and for azadirachtin 2gr a.i./100lt water. In the present study an attempt was The concentrations of the insecticides so- made to determine the toxic eff ect of vari- lutions were calculated based on the prod- ous insecticides, with diff erent mode of ac- uct labels and were similar with those that tion, to nymphs and adults of the grasshop- were used in agricultural practice against per C. barbarus barbarus under laboratory Orthoptera or other insect pests. conditions. In addition, the lethal time of the 50% and 90% of the grasshopper popu- Bioassays lation by these insecticides was estimated. To test the toxic eff ect of the insecticides to C. barbarus barbarus nymphs and adults, a water solution of each insecticide was pre- Materials and methods pared (1.5 lt) using the above mentioned doses. Fully expanded mature leaves of vine Biological material (Vitis vinifera, cv Sultanina) were dipped The experiments were conducted with in each insecticide solution, removed and nymphs (mixed population of 3rd and 4th in- dried at 30°C for 30-40 min (Amaraseka- star) as well as with adults of C. barbarus bar- re and Edelson, 2004). Water treated leaves barus. Nymphs of early instars (1st and 2nd) were used as control. To keep the leaf turgid, were collected by sweep netting in a lowland the stem was placed in a vial of water. Ev- grassland area near Spata (Attica – Greece). ery leaf was placed separately in a clear plas- After the collection, the insects were trans- tic cage (1lt volume) bearing an opening at ferred to the laboratory and reared in exper- the top covered with fi ne muslin. Eight indi- imental wood-framed cages (30 x 30 x 30 viduals (4 males and 4 females), nymphs or cm), 20-30 nymphs in each cage, at a tem- adults, of C. barbarus barbarus were placed perature of 25 ± 1°C, humidity 65 ± 5% and in each cage and remained under starvation a photoperiod 16: 8 light: dark (Lactin and for 24 hours before their use in bioassays. Johnson, 1995; De Faria et al., 1999). Insects The treated leaf was kept in the cage for 48 were fed with vine leaves, placed in the cag- hours and then was replaced with an un- es daily. Water was provided through a piece treated leaf every 48 hours, for 10 days. Wa- of water soaked cotton placed on the bot- ter was provided to the insects via a piece of tom of each cage. The adults were kept in water soaked cotton placed at the bottom cages of same dimensions and fed also with of each cage. The toxicity of insecticides vine leaves until used in bioassays. was determined by the mortality of grasshoppers over the 10-day observation period (Amarasekare and Edelson, 2004). Counting © Benaki Phytopathological Institute Toxicity of insecticides to Calliptamus barbarus barbarus 45 of live and dead insects was conducted eve- zuron and azadirachtin, respectively, which ry 24 hours. An insect was considered dead did not signifi cantly diff er from the level ob- if no movement was observed after a gentle tained from the water control. Ten days af- disturbance. The bioassays were conduct- ter treatment the mortalities obtained from ed in chambers in which the humidity was these insecticides were 53.1% and 29.7% and 65±5% and the temperature 25±1 οC. Cool were signifi cantly higher than the level ob- fl uorescent light provided a photoperiod of tained from the water control. The mortality 16: 8 light: dark. There were 8 replicates for of grasshopper nymphs that was observed each treatment. after their exposure to difl ubenzuron was diff erent from the mortality obtained from Statistical analysis the water control the last six days of the trial, Data obtained from the bioassays on while those of azadirachtin was greater than nymphs and adults of C. barbarus barbarus that of the control only the last day of the tri- were analyzed using Kruskal-Wallis H-test al (Table 1). and comparison of means were performed The LT50 and LT90 values for nymphs of C. with Mann-Whitney U-test for P=0.05. The barbarus barbarus, when the insects were statistical analysis was conducted using the exposed to the treated leaves for 48h var- software Statistica 7 (StatSoft Inc., 2004). ied from 0.83 to 15.79 days and from 3.3 to Moreover, the data of bioassays were sub- 35.02 days, respectively (Table 2). The short- jected to probit analysis to calculate the le- est time to kill the 50% as well as the 90% of thal time required for 50% (LT50) and 90% the grasshopper nymphs was recorded after (LT90) of the insects after their exposure to their exposure to spinosad followed in as- the treated leaves for 48 hours. The analy- cending order by imidacloprid, alpha cyper- sis was performed using the software SPSS methrin, difl ubenzuron and azadirachtin.

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