Chitinases are found in species from all kingdoms, including Kingdom Animalia. We purified chitinase, poly [1,4-(N-acetyl-β-d-glucosaminide)] glycanohydrolase, by cation exchange chromatography on SP-Sepharose from the integument of a lepidopteran, the Mediterranean flour moth, Ephestia kuehniella Zeller, and further characterized it. Ephestia kuehniella chitinase has similar properties to other insect chitinases, with respect to the molecular mass. Its molecular mass was 79.7 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature for activity were 6 and 40 °C, respectively. The purified enzyme exhibited stability at a pH range from 4.5 to 8.0 and showed high sensitivity to Co2+, Mn2+, Ca2+, Hg2+ and Ag+. The Km and Vmax values of E. kuehniella chitinase were, respectively, 3.98 mg/mL and 7.11 μmol/min/mg for colloidal chitin. In comparison to the values determined for the substrate affinity, the enzyme had a 2.36-fold higher affinity for Carboxymethyl–Chitin–Remazol Brilliant Violet (CM–Chitin–RBV) as a soluble substrate. We examined the antibacterial effect of E. kuehniella chitinase on the growth of both Gram-positive and Gram-negative bacteria. The enzyme inhibited the growth of Bacillus subtilis, Bacillus thuringiensis and Escherichia coli, where the average diameter of inhibition zone was 20, 23 and 19 mm, respectively. The antimicrobial effect and chitinase activity strengthen the hypothesis that the enzyme could be used in biological control against plant pests.

Outbreaks of three orthopteran species—Tropidacris collaris (Stoll), Cornops frenatum frenatum (Marschall) and Parascopas obesus (Giglio-Tos)—occurred in three different regions of Brazil during the summers of 2012 and 2013. Insects were observed causing severe damage in commercial crops and subsistence farming areas. In this study, the three species were shown to be susceptible to infection with an oil-based formulation of the fungus Metarhizium acridum under laboratory conditions. In this article, we briefly discuss insect mortality levels for each species and behavioural response to infection. This is the first report of the pathogenicity of the entomopathogenic fungus M. acridum to P. obesus, C. f. frenatum and T. collaris.

Cacao mirids (Sahlbergella singularis, Distantiella theobroma and Bryocoropsis laticollis) were captured in pheromone traps releasing a 2:1 blend of the sex pheromone components of the two first named species in a series of five experiments on cacao (Theobroma cacao) plantations in Ghana. A total of 835 cacao mirids were caught, all male, 95% of which were S. singularis, 3% D. theobroma and 2% B. laticollis. Two sticky trap and two water trap designs made from locally available materials were as effective for capturing S. singularis and total mirids as the best sticky trap from previously reported studies. Coating the outer surface of a large water trap with sticker increased the catch 4.4×, and 2.7× for a cylindrical sticky trap. Sticker on the outside of the water trap also increased the inside catch of S. singularis by 76% and total mirids by 71%. The numbers of S. singularis and D. theobroma trapped increased with increasing trap elevation and were highest around canopy level. Those traps caught an average 12× more mirids than traps at 1.8 m, the height recommended currently. Therefore, large water traps coated with sticker and aligned with the cacao canopy should raise the current capture rates of pheromone traps for cacao mirids about 50×, which may be sufficient for effective pest management by mass trapping without synthetic insecticides.

In this study, we investigate the spatio-temporal fluctuations of the cashew leafminer Eteoryctis gemoniella Stainton, which was recently reported as one of the most devastating cashew pests in Benin. Eteoryctis gemoniella causes serious damage, especially to the young tender leaves, thus reducing the photosynthetic capacity of trees and hence their productivity. This study was carried out in three different cashew orchards in Northern Benin, West Africa, where we monitored the fluctuations of the infestation rates and population changes of E. gemoniella during a one-year cycle, from September 2010 to August 2011. In addition, we collected cashew leaves with mines to check for emergence of hymenopteran parasitoids. Our results show that infestation rates (as well as population densities of E. gemoniella) varied through time and among orchards. The most infested orchard was at Korou, whereas, the least infested was at Okoutaossé. In general, infestation rates and number of mines per leaf passed through two peaks, the first in July–August and the second in November, whereas no infestations were observed from January to June. Spatial distribution pattern of E. gemoniella within the orchards showed that this moth almost has a random distribution. Parasitoids attacking the leafminer were recovered from the samples. These were Apanteles sp., Chelonus (Microchelonus) nr. curvimaculatus Cameron (Hymenoptera: Braconidae) and Trathala sp. (Hymenoptera: Ichneumonidae). Further detailed studies on these natural enemies will be needed for evaluating their potential in controlling E. gemoniella in cashew orchards.

Zygogramma bicolorata Pallister is a potential biocontrol agent of Parthenium hysterophorus L. (Asteraceae). This study was carried out to understand the effect of abiotic (temperature and moisture) and biotic factors (age and reproductive status) on the induction and termination of diapause in Z. bicolorata. We also evaluated the effect of diapause on longevity and fecundity of Z. bicolorata. In Z. bicolorata the induction of diapause occurred between the months of July and December. No diapause was observed in May and June, which coincided with the commencement of the monsoon rains. The percentage of diapause induction in Z. bicolorata was found to increase from one generation to another as well as with the age of adults. Diapause significantly increased the fecundity of females as compared to the fecundity in pre-diapause conditions. Soil moisture (80% RH) played an important role in providing the conditions for initiation and termination of diapause. Similarly, 18.4 and 12.5% of diapause adults resumed their activity in 6 and 5 days when exposed to temperatures of 40° and 45° C for 2 h every day, respectively. Exposure of adults to low temperatures, i.e. 5° and 10° C induced 94.3 and 92.5% diapause, respectively, with no adult mortality. Thus, our findings reveal suitable conditions for preventing and inducing diapause in Z. bicolorata, which is of great importance in the suppression of P. hysterophorus. We discuss the implications of these findings in the control of P. hysterophorus.

Effects of pesticidal plant extracts on non-targeted species are rare. Direct topical and residual sprays of crude aqueous extracts of three pesticidal plants: Datura stramonium L. Bobgunnia madagascariensis Kirkbr. & Wiersema and Solanum delagoense L. were assessed in laboratory bioassays and on-station experiments against the ladybird beetle, Hippodamia variegata (Goeze). The plants are routinely used by smallholder vegetable farmers to control aphids, Brevicoryne brassicae L. attacking rape, Brassica napus L. The crude extracts of D. stramonium fresh leaves, S. delagoense fresh fruits and B. madagascariensis dried pods, were applied separately at 5, 10, 15, 20 and 25% w/v under laboratory conditions. Application rates of 20% and 25% w/v of the plant extracts were further evaluated on-station. Negative (tap water) and positive (dimethoate® (36% E.C)) controls were included for comparison. The mortality of H. variegata was recorded 24, 48 and 72 h post-exposure. In on-station experiments, treatments were applied fortnightly and live H. variegata adults were counted at 1, 7 and 14 days post-application. Mortality of H. variegata in laboratory bioassays increased with increase in post-exposure time and B. madagascariensis (25% w/v) caused the highest mortality. Based on LD50 values, B. madagascariensis extracts were most toxic (LD50, 30% w/v) followed by D. stramonium (LD50, 34% w/v) and S. delagoense (LD50, 49% w/v) 24 h post-application. In on-station experiments, the synthetic chemical significantly lowered (P < 0.05) H. variegata numbers compared to the negative control and plant extracts. The results showed that D. stramonium and S. delagoense extracts at the application rates used in the study were relatively safer to H. variegata than B. madagascariensis (25% w/v); hence, the former two plants can be included in integrated pest management programmes.