The efficacy of spinosad against the diamondback moth (DBM) on cabbage was studied at Botswana College of Agriculture, Gaborone, Botswana in 2011. Using five concentrations of spinosad: 0.12, 0.36, 0.60, 0.84 and 1.08 g/L, bioassays were conducted against DBM eggs and second instar larvae at 30°C ± 5°C. Each treatment was replicated three times. Probit analysis was used to determine LD₅₀ and LD₉₀ values for the treatments against eggs and larvae. When the treatments were assessed at 72 and 96 hours, LD₉₀ values against larvae were 0.74 and 0.59 g/L, whereas they were 0.35 and 0.32 g/L against eggs. This indicated that spinosad was more effective against eggs than against larvae. The slopes of the probit lines for larvae assessed at 48, 72 and 96 hours after application were 3.519, 3.810 and 3.427, while those against eggs were 1.725, 1.316 and 1.086. This indicates that there was a more rapid change in larval mortality with increase in pesticide dosage than in egg mortality. The study shows that spinosad can achieve effective control of DBM eggs and larvae under Botswana conditions.

The assessment of the morphological and reproductive features of white rice leafhopper Cofana spectra (Distant) was carried out using selected characters that bear importance in determining the fitness at the individual and population levels. Morphometric measurements of the individuals reared in the laboratory as normal and stylopized with the strepsipteran parasitoid, Halictophagus australensis Perkins, were recorded and analyzed. A t-test was performed to justify whether parasitization by H. australensis affected the traits. Correlations and regression analyses were carried out to deduce the difference in relative importance of the morphological features in the life history of C. spectra and their variation because of stylopization by H. australensis. A principal component analysis (PCA) was applied on the morphometric data to further substantiate the difference observed in the traits. In case of stylopized white leafhopper (WLH), fecundity was inhibited almost completely irrespective of seasons. The effect of stylopization on the life history traits of C. spectra has been noted that supports its possible use in biocontrol.

Silk cocoon nests, as well as the fiber structure, compositions, and properties of the African wild silkmoth, Anaphe panda, collected from Kakamega tropical rainforest (western Kenya) were studied using scanning electron microscopy, high-pressureliquid chromatography, tensile tests, and thermogravmetric analysis, and they were compared with the industrial standard, Bombyx mori. Cocoon nests are complex structures made up of inner, middle, and outer layers. The inner hard parchment was found to protect a mass of (20–200) individual soft flossy cocoons that enclose the pupae. The outer surface of the cocoon nests was covered with a mass of hair-like bristles. Fibers contained crescent-shaped and globular cross-sections with nods at regular intervals. Alanine (34%) and glycine (28%) were the dominant fibroin amino acids observed. Total weight loss after degumming the cocoon nest was 25.6%. Degummed fibers showed higher moisture regain of 9% when compared with cocoon nests (8%). The fibers had 0.4 GPa breaking stress and 15.4% breaking strain. Total weight loss values after thermogravimetric analysis were 86% and 90% for degummed fibers and cocoon shells, respectively.

The present study illustrates that different day intervals (DIs) between the sequential infestations of two pest species, the rice leaffolder (RLF) Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae) and the white-backed rice planthopper (WBPH) Sogatella furcifera Horváth (Hemiptera: Delphacidae), have a significant impact on the rice yield loss rate (YLR) and on the carbohydrate contents of rice plants. For WBPH release after RLF release (WRARR), the YLR decreased with the increasing DIs, and the YLR at the 24 DI was significantly lower compared to that at the 6 and 12 DIs and had a minimum value for a simultaneous infestation of the two pest species (SITS). In contrast, for RLF release after WBPH release (RRAWR), the YLR at the 24 DI had a maximum value and was significantly higher compared to that at the 6 and 12 DIs and the SITS. These findings indicate that damaged rice plants gradually recover, with an increase in the DI for WRARR. The above results were demonstrated by biochemical tests. Therefore, the sequential infestation of the two pest species and their DIs should be considered for integrated pest management (IPM) and control strategies for rice pests.

Efficacy of the combined treatment of a neem oil formulation and endosulfan on feeding and midgut enzyme activities of Helicoverpa armigera larvae was studied. The antifeedant activity was recorded at 24 h after treatment and the activities of midgut digestive (total serine protease and trypsin) and detoxifying (esterase and glutathione-S-transferase) enzymes were estimated at 72 h after treatment. The antifeedant activity in endosulfan + neem oil formulation (endosulfan 0.01% and neem oil formulation 1% at 1:1 ratio) was 85.34%, significantly greater than in individual treatments. Midgut digestive enzymes and EST activities were significantly reduced and the GST activity significantly increased in the combined treatment of endosulfan + neem oil formulation, thus showing increased effect of the combined treatment of the two pesticides. These results suggest that neem oil can be used in combination with endosulfan to reduce its quantity.

The effects of ecosystem fragmentation on biodiversity during urbanization are well established. As a city grows, it replaces much of the native plant life with asphalt, cement, and lawns, yet small patches of native plants remain in greenspaces, which act as refugia for native animals. However, little work has been done on the patterns of re-colonization by native animals as urban decay allows for re-establishment of native plant communities. We found that patterns of biodiversity in the insect herbivore community within an archipelago of abandoned lots follow patterns of island biogeography, with higher biodiversity on large islands. We also found that insect colonization of the abandoned lots was correlated with each species' dispersal ability. The patterns seen here have implications for patterns of species movement into urban systems as new parks are established or as abandoned lots are re-colonized by native plants.

The horn fly, Haematobia irritans irritans (L.), is an ectoparasitic blood feeder mainly on cattle. Its cosmopolitan distribution extends from boreal and grassland regions in northern and southern latitudes to the tropics. Stress and blood loss from horn flies can reduce cattle weight gain and milk production. Horn flies show substantial plasticity in their response to winter. Populations in warmer, lower latitudes have been reported to overwinter in a state of dormancy, but most overwinter as active adults in normal or reduced numbers. As latitudes increase, winters are generally colder, and correspondingly, larger percentages of horn fly populations become dormant as pharate adults (a post-pupal, pre-emergent stage) or die. Reports on the effect of elevation on horn fly dormancy at high elevations were contradictory. When it occurs, dormancy takes place beneath cattle dung pats and in the underlying soil. The horn fly's mode of dormancy is commonly called diapause, but the collective research on horn fly diapause (behavioral and biochemical) is not conclusive. Understanding the horn fly's overwintering behaviors can lead to development of pre-dormancy insecticide spray strategies in colder latitudes while other strategies must be determined for warmer regions.

The grain-sucking bug, Stenocoris elegans Blöte (Hemiptera: Alydidae), is an important rice pest in West Africa. Investigation on its developmental biology is important to provide the base and possibility to bring forth further research for the improvement of the pest management strategy. The developmental biology of S. elegans was investigated on upland rice variety IDSA 10 in the laboratory in Ibadan, Nigeria. The results showed that pre-oviposition and post-oviposition periods were 9.9 ± 0.49 and 6.1 ± 1.17 days, respectively, under ambient temperature and relative humidity. A mated female of S. elegans laid an average of 135.1 eggs during an oviposition period of 33.5 days. The average egg incubation period was 7.9 ± 0.3 days. There were five nymphal instars, and the total developmental period (first instar to adult) averaged 18.0 days. An over-all mean growth ratio of 1.29 was recorded for this species. A regular relationship existed between measurements of nymphal vertex and the duration of their developmental periods, and a significant correlation (0.98) was obtained.

In China, the pink stem borer (PSB) Sesamia inferens (Walker) (Lepidoptera: Noctuidae) has become a rice pest in some rice-producing regions. The cause of this shift from secondary to major pest is unknown. The major purpose of this study was to examine the effect of five commonly used pesticides in rice fields on reproduction of PSB and on biochemical substances of rice plants. The results showed that the weight of pupae developed from 1st instar larvae treated with 2 mg/L triazophos and the number of eggs laid by emerged females from the treatment were significantly greater than those of the control, increasing by 26.2% and 47%, respectively. In addition, a nontarget insecticide, pymetrozine 100 mg/L, and a target insecticide, chlorantraniliprole 2 mg/L, stimulated reproduction of PSB. Biochemical measurement showed that foliar sprays of these pesticides resulted in significant reductions of contents of resistant substances, flavonoids and phenolic acids, in rice plants. For example, flavonoids and phenolic acids of rice plants treated with triazophos reduced by 48.5% and 22.4%, respectively, compared to the control. Therefore, we predicted that the application of some pesticides, eg triazophos and chlorantraniliprole, may be the cause of the increase in the population numbers of PSB in rice fields.

The possible cellular involvements of cowpea storage bruchid (Callosobruchus maculatus (Fab.) [Coleoptera: Chrysomelidae]) glutathione and its related enzymes system in the cellular defense against insecticides (Cypermethrin and lgr;-cyhalothrin) and bio-insecticides (ethanolic extract of Tithonia diversifolia, Cyperus rotundus, Hyptis suavolens leaves, and Jatropha curcas seed) were investigated. The results showed that the effect of insecticides and bio-insecticides on the C. maculatus is a function of oxidative and nitrosative stresses generated in vivo. A significant (p < 0.05) increase in carbonyl protein (CP) and lipid peroxidation (LPO) contents in bio-insecticides and insecticides exposed groups compared to the control indicates the extent of vital organs damage. These stresses caused similar and significant increase of glutathione peroxidase and glutathione synthetase in response to insecticides and bio-insecticide exposure in a dose-dependent manner. There was no post-translational modification of glutathione transferases expression induced. The alterations of the insect glutathione-dependent antioxidant enzyme activities reflect the presence of a functional defense mechanism against the oxidative and nitrosative stress and are related firmly to the glutathione demands and metabolism but appear inadequate by the significant reduction in glutathione reductase (GR) activity to prevent the damages. Exogenous application of reduced glutathione (GSH), to complement the in vivo demand, could not protect against the onslaught.

Present investigations evaluated the impact of Argemone mexicana stem extracts on the reproductive fitness of dengue vector, Aedes aegypti, assessed in terms of oviposition deterrent and ovicidal potential. The oviposition deterrent studies of the extracts, prepared using petroleum ether, hexane, benzene, acetone, and ethanol as the solvents, revealed the maximum deterrence potency of the petroleum ether extracts with a significant 15.6% ED at 60 ppm rising by 83.8% at 1000 ppm to 99.4% effective deterrence (ED). Other stem extracts were found to be ineffective at 60 ppm, though resulted in 85.3–96.2% ED and diminished fecundity in A. aegypti at 1000 ppm. Further, A. mexicana stem extracts exhibited moderate ovicidal potential against A. aegypti eggs causing only 42.65–67.85% egg mortality at 1000 ppm, the lowest hatch of 32.15% caused by the benzene extract. Other stem extracts also failed to express effective ovicidal potency with the percent egg hatch ranging between 96.6 and 99.0 at 400 ppm, and 78.8 and 99.0 at 600 ppm. Our results suggest the significant but variable efficacy of A. mexicana stem extracts causing reproductive disadvantage in A. aegypti.

The non-enzymatic and enzymatic antioxidant defense systems play a major role in detoxification of pro-oxidant endobiotics and xenobiotics. The possible involvement of beetle non-enzymatic [α-tocopherol, glutathione (GSH), and ascorbic acid] and enzymatic [catalase (CAT), superoxide dismutase (SOD), peroxidase (POX), and polyphenol oxidase (PPO)] antioxidant defense system on the insecticidal activity of synthetic insecticides (cypermethrin, 2,2-dicholorovinyl dimethyl phosphate, and lgr;-cyhalothrin) and ethanolic plant extracts of Tithonia diversifolia, Cyperus rotundus, Hyptis suaveolens leaves, and Jatropha Curcas seeds was investigated. 2,2-Dicholorovinyl dimethyl phosphate (DDVP; 200 ppm, LC₅₀ = 13.24 ppm) and T. diversifolia (20,000 ppm) resulted in 100% beetle mortality at 96-hour post-treatment. The post-treatments significantly increased the beetle α-tocopherol and GSH contents. Activities of CAT, SOD, POX, and PPO were modulated by the synthetic insecticides and bioinsecticides to diminish the adverse effect of the chemical stresses. Quantitative and qualitative allelochemical compositions of bioinsecticides and chemical structure of synthetic insecticides possibly account and for modulation of their respective enzyme activities. Altogether, oxidative stress was enormous enough to cause maladaptation in insects. This study established that oxidative imbalance created could be the molecular basis of the efficacy of both insecticides and bio-insecticides. Two, there was development of functional but inadequate antioxidant defense mechanism in the beetle.

The navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), is a key pest of high-value irrigated nut crops in the arid Central Valley of California. Mating disruption is an established pest management technique for this pest, with reduced non-target impacts. This study compared laboratory survivorship and fertility data with field measurements to improve understanding of factors determining abundance of this species in the presence and absence of mating disruption. While the relative humidity is generally higher in almond orchards compared to readings from meteorological stations, the data indicate little free water in the absence of irrigation. Access to free water has a minor effect on the fertility of females if they mate soon after emergence, but a major effect if mating is delayed for 7 days. Leslie matrix projections indicate that changes in adult survivorship have much less impact than changes in larval survivorship. These findings indicate that control tactics limiting reproduction and survival of immature stages are more important for this species than those targeting adults.