Indoxacarb resistance in Iranian populations of Tuta absoluta (Lepidoptera: Gelechiidae): Cross-resistance, biochemical and molecular mechanisms.

Tuta absoluta (Meyrick) is an invasive tomato pest that occurs worldwide, including Iran. This study investigates the occurrence of resistance to indoxacarb, an oxadiazine insecticide, and the underlying mechanisms in Iranian populations of T. absoluta. Bioassays were performed on second-instar larvae using indoxacarb alone and in combination with three synergists: Piperonyl butoxide (PBO), diethyl maleate (DEM), and triphenyl phosphate (TPP). The activities of the main detoxification enzymes, including glutathione S-transferases (GST), general carboxylesterases (CarEs), and P450 monooxygenases (P450s), were evaluated. In addition, the presence of known amino acid substitutions in the IV segment 6 domain of the T. absoluta sodium channel was investigated. The results showed that resistance rates to indoxacarb in Iranian populations ranged from 2.37- to 14.45-fold. However, pretreatment with synergists did not significantly increase the toxicity of indoxacarb. Enzyme assays showed that Ardabil (Ar) and Kerman (Kr) populations had the highest CarEs activity, while Ar population showed the highest P450 activity. However, the observed increases in enzyme activities were <2-fold. Two indoxacarb resistance mutations, F1845Y and V1848I, were detected. Apart from a significant and positive correlation between LC50 values of indoxacarb and thiocyclam hydrogen oxalate, no cross-resistance between indoxacarb and other insecticides was detected. Overall, these results suggest that populations of T. absoluta in Iran have developed resistance to indoxacarb, primarily through changes at the target site.

Interaction between biological parameters of Panonychus citri (Acari: Tetranychidae) and some phytochemical metabolites in different citrus species.

The citrus red mite, Panonychus citri McGregor, is a key pest of different citrus species in various parts of the world. Considering the key role of resistant host plants in integrated pest management strategies, we evaluated the effects of five citrus species including grapefruit (Citrus paradisi), lime (Citrus aurantifolia), tangerine (Citrus reticulata), orange (Citrus sinensis), and sour orange (Citrus aurantium) on life table parameters of P. citri under laboratory conditions (25 ± 1°C, 65 ± 5% RH, 16:8 L:D). In addition, biochemical traits of the citrus plant species were evaluated in order to understand any possible relationship between important life history parameters with biochemical metabolites of citrus plant leaves. Phytochemicals were determined in leaf extract of citrus plant species. Various citrus species had significant effects on life history and demographical parameters of P. citri. The longest pre-adult time was observed on grapefruit (16.52 ± 0.43 days). Higher fecundity rate was on orange (15.05 ± 2.41 eggs) and tangerine (14.60 ± 3.07 eggs) and the lowest was on grapefruit (7.21 ± 2.00 eggs). The highest intrinsic rate of increase (r) was recorded as 0.071 (day-1) on tangerine, and the lowest value of this parameter was obtained on grapefruit (0.016 day-1). Significant correlations were observed between life history parameters with biochemical metabolites (carbohydrate, phenolic compounds, anthocyanin, and flavonoid). The results revealed that grapefruit was a relatively resistant host plant and tangerine was the most suitable host plant for feeding of P. citri. Our findings could be helpful for sustainable management of P. citri in citrus orchards.

Effect of Different Fruit Developmental Stages and Biochemical Metabolites of Pomegranate (Ponicaceae) on Life History Parameters of Ectomyelois ceratoniae (Lepidoptera: Pyralidae).

Plant-herbivore interactions can be influenced by plant developmental stages. Effects of four different developmental stages of pomegranate fruit (Hazelnut size, Walnut size, Juicy, and Ripe) were investigated on life table parameters, nutritional yield, and energy contents (protein, glycogen, and lipid) of Ectomyelois ceratoniae (Zeller) under controlled conditions in two pomegranate cultivars, namely Shahvare-Danesefid and Esfahani-Daneghermez as susceptible and resistant cultivars, respectively. Biochemical characteristics of the four developmental stages were determined, and a correlation was made with life-history and nutritional responses of E. ceratoniae. Significant differences were observed in developmental time and adult fecundity of E. ceratoniae across various tested stages in both pomegranate cultivars. The highest value of intrinsic rate of increase (rm) was found in Juicy and lowest in Hazelnut-size stage of Shahvare-Danesefid. The highest rm value was on Walnut-size and Juicy stages, and the lower rate was obtained from the feeding of E. ceratoniae on Ripe and Hazelnut-size stages in Esfahani-Daneghermez. A higher relative growth rate (RGR) was observed in Juicy (in Shahvare-Danesefid) and Walnut-size stages (in Esfahani-Daneghermez) when compared with other developmental stages tested. Life-history parameters of E. ceratoniae were correlated with biochemical qualities of pomegranate stages. Results indicated Juicy (Shahvare-Danesefid) and Walnut-size stages (Esfahani-Daneghermez) were relatively susceptible pomegranate stages, and Hazelnut-size and Ripe stages were unsuitable for feeding of E. ceratoniae in Shahvare-Danesefid and Esfahani-Daneghermez, respectively. Findings of this research could aid in the development of integrated management programs of E. ceratoniae in pomegranate orchards.

Relationship Between Performance of Carob Moth, Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae) and Phytochemical Metabolites in Various Pomegranate Cultivars.

The carob moth, Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae), is the main pest of pomegranate, Punica granatum L., in Iran and many parts of the world. In this study, the effects of 11 commercial cultivars of pomegranate (Aban-Mahi, Esfahani-Daneghermez, Gabri, Gorche-Tafti, Malase-Danesyah, Malase-Yazdi, Shahvare-Daneghermez, Shahvare-Danesefid, Tabolarze-Mehrmahi, Tafti, and Toghe-Gardan) were evaluated on life history variables, nutritional performance, and energy reserves of E. ceratoniae under the following laboratory conditions: 30 ± 1°C, 60 ± 5% RH, and a photoperiod of 14:10 (L:D) hours. In addition, biochemical characteristics of the tested cultivars were assessed in order to understand any possible correlation between important demographic parameters and nutritional properties with biochemical features of pomegranate juice. Our research showed that various pomegranate cultivars have significant effects on life history, demographical parameters, nutritional indices, and energy reserves of E. ceratoniae. The shortest development time was observed on Shahvare-Danesefid cultivar and the longest was on Esfahani-Daneghermez and Malase-Danesyah cultivars. The highest intrinsic rate of increase (r m ) was observed on Shahvare-Danesefid and the lowest was on Esfahani-Daneghermez. Six major anthocyanin compounds were detected in juice of various pomegranate cultivars. Significant positive or negative correlations were observed between life history variables and nutritional characteristics with biochemical traits of pomegranate cultivars. The results indicated that Shahvare-Danesefid was a relatively susceptible pomegranate cultivar and Esfahani-Daneghermez was the least appropriate (most resistant) cultivar for feeding of E. ceratoniae, which could be useful in the development of integrated pest management strategies for this pest.

Tritrophic Interactions of Cucumber Cultivar, Aphis gossypii (Hemiptera: Aphididae), and Its Predator Hippodamia variegata (Coleoptera: Coccinellidae).

The melon aphid, Aphis gossypii Glover, is a cosmopolitan pest that infests and damages a wide range of crop plants, especially cucurbits. It is a host of the coccinellid predator, Hippodamia variegata (Goeze), that has the potential to suppress the pest on leaves of cucumber plants grown in greenhouses. Melon aphids were reared on either Storm or Khasib cucumber cultivars to determine whether there would be a difference in their development and reproduction. The aphids from each cultivar were fed to H. variegata adults to assess their effects on the life history of the predator. The aphid population reared on Khasib leaves increased faster than the population on Storm leaves; however, the predators fed aphids from Storm leaves had a higher rate of population growth. Thus, the intrinsic rate of increase and net reproductive rate were greater for aphids reared on Khasib leaves but lower for H. variegata fed those aphids compared with aphids reared on the Storm cultivar. Additionally, clean and aphid-infested leaves from both cultivars were analyzed for total flavonoids, phenol, and chlorophyll, and the density of leaf trichomes was measured. The Storm leaves contained higher amounts of flavonoids and phenol, less chlorophyll, and a greater density of trichomes. Regardless of cucurbit cultivar, aphid feeding increased the flavonoids and phenol content and decreased the amount of chlorophyll.

Life Table Parameters and Oviposition Preference of Plutella xylostella (Lepidoptera: Plutellidae) on Six Brassicaceous Crop Plants.

The oviposition preferences and larval development of the diamondback moth, Plutella xylostella (L.), were evaluated in the laboratory on canola, Brassica napus L. and five Brassica oleracea L. cultivars: broccoli, cauliflower, kohlrabi, red cabbage, and white cabbage. Adults from larvae fed on cauliflower and canola lived longer than those fed other cultivars, whereas the oviposition period was longest for cauliflower (5.54 d) and shortest for females reared on kohlrabi (2.68 d). The oviposition period for canola and broccoli was relatively long compared with white cabbage, red cabbage, and kohlrabi. Significantly more eggs were oviposited on cauliflower (163.71 eggs per female) than on canola (139.23 eggs per female) and the other B. oleracea cultivars, although broccoli also was preferred over white cabbage, red cabbage, and kohlrabi. The differences in total development times of immature stages on Brassica plants tested were significant, being shortest on cauliflower (17.60 d) and longest on kohlrabi (21.12 d). The moths reared on cauliflower and Kohlrabi, respectively, had the highest (65.46 offspring per individual) and lowest (12.71 offspring per individual) R0 values. Also, moths reared on cauliflower had significantly higher r value (0.200 d-1). The lowest r value was obtained when individuals fed on Kohlrabi (0.105 d-1). In free-choice situation, oviposition on canola and cauliflower was similar, but numbers of eggs deposited on these plants exceeded other plants. The amounts of glucosinolate were significantly greater in canola and cauliflower, intermediate in white cabbage, lower in broccoli and kohlrabi, and the lowest in red cabbage.

Host Plant-Herbivore-Predator Interactions in Chrysoperla carnea (Neuroptera: Chrysopidae) and Myzus persicae (Homoptera: Aphididae) on Four Plant Species Under Laboratory Conditions.

The common green lacewing, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), is a well-known biocontrol agent. The current study examined host plant-herbivore-predator interactions with C. carnea and Myzus persicae on four host plants (peach, almond, pepper, and potato). The experiments were carried out at 25 ± 1°C and 65 ± 5% RH at a photoperiod of 16:8 (L:D) h). Duration of the preadult growth period, adult longevity, fecundity, and population growth parameters were analyzed based on the age-stage, two-sex life table theory. The shortest and longest preadult developmental times of the predator were observed on the peach and potato, respectively. The highest and lowest predation rate, oviposition period, and male and female longevity of predator were also observed on the peach and potato, respectively. The lowest intrinsic rate of increase (r) and finite rate of increase (λ) were observed on the potato (0.1087 and 1.11 d-1, respectively) and the highest on the peach (0.1460 and 1.15 d-1, respectively). The maximum and minimum mean generation times (T) were 41.84 and 35.59 d in the potato and peach, respectively. Overall, peach was found to be a more appropriate host than the other host plants for development and predation fitness of C. carnea. These findings reveal that information on tritrophic interactions and subsequent life table evaluation of natural enemies improves integrated pest management programs.

Effects of Chemical, Organic and Bio-Fertilizers on Some Secondary Metabolites in the Leaves of Bell Pepper ( Capsicum annuum ) and Their Impact on Life Table Parameters of Myzus persicae (Hemiptera: Aphididae).

The green peach aphid, Myzus persicae (Sulzer), is a polyphagous and a holocyclic aphid that causes severe damage on hundreds of host plants in both fields and greenhouses. In this research, the effects of Zinc sulfate spray and amending the soil with 30% vermicompost, Bacillus subtilis , Pseudomonas fluorescens , Glomus intraradices , G. intraradices × B. subtilis , and G. intraradices × P. fluorescens compared with no fertilizer treatments were investigated on secondary metabolites in the leaves of bell pepper and life table parameters of M. persicae . Total phenol contents in the plant leaves varied significantly among different fertilizer treatments. The highest (72.28 mg/ml) value was observed on 30% vermicompost. Life table parameters of M. persicae were significantly affected by different fertilizer treatments. The net reproductive rate ( R 0 ) of M. persicae fed on plants treated with different fertilizer treatments varied from 4.38 to 21.93 female offspring, with the lowest and highest values on 30% vermicompost and Zinc sulfate, respectively. The lowest and the highest intrinsic rate of increase ( r m ) were also observed on 30% vermicompost and Zinc sulfate (0.111 and 0.321 female per female per day, respectively). The longest mean generation time ( T ) was recorded on 30% vermicompost (13.41 d), and the shortest generation time was observed on Zinc sulfate (9.61 d). Results of this study revealed that amending the soil with 30% vermicompost significantly affected the life table parameters of M. persicae . Thus, it was concluded that amending the soil of bell pepper with 30% vermicompost can provide an environmentally safe and efficient control of this aphid.