Scirtothrips dorsalis Hood is a polyphagous species and an important sucking pest of tea (Camellia sinensis) (Theaceae). The fitness traits of S. dorsalis on two alternative host plants: Capsicum annuum L. (chilli) (Solanaceae) and Ricinus communis (castor oil plant) (Euphorbiaceae) and on C. sinensis and corresponding levels of defence enzymes was studied. The study revealed that C. sinensis is the more suitable host of S. dorsalis based on faster development (13.6 days) compared to the alternative hosts, C. annuum (15.5 days) and R. communis (16.7 days), a higher fecundity (C. sinensis: 11.4 eggs; C. annuum: 9.7 eggs; R. communis: 8.6 eggs), and superior egg hatchability (C. sinensis, 92.6%; C. annuum: 82.5%; and R. communis: 74.6%). The host-based variation in the fitness traits of S. dorsalis corroborated in light of differential activity of three major detoxifying enzymes, such as the general esterases (GEs), glutathione S-transferases (GSTs), and cytochrome P450 mediated monooxygenases (CYPs). Densitometric analysis of GEs showed five esterase isozymes (EST I–V) with retardation factor (Rf) values of 0.17, 0.22, 0.27, 0.35 and 0.52, respectively. The pixel density, and accordingly the profile height, varied in different host-specific S. dorsalis. A significant variation of the quantity of these enzymes was also apparent in the insect when reared on the three hosts. A 2.4 and 2.7, 1.6 and 2.0, and 2.0 and 2.3-fold higher GEs, GSTs and CYPs activity on the two non-tea hosts possibly signify a predisposition of the species for higher tolerance to insecticides, enabling the pest to switch to tea where synthetic insecticides are routinely used.

The antestia bug Antestiopsis thunbergii (Gmelin 1790) is a major coffee pest in East Africa. Nymphs and adults feed on all vegetative and fruiting parts of the coffee tree leading to yield reduction and poor quality of coffee beans. Our study aimed to characterize the developmental biology and provide life table parameters for A. thunbergii reared in the laboratory. The biology of A. thunbergii was studied at four constant temperatures of 20, 25, 30 and 35°C with 80±5% RH and a photoperiod of L:D 12:12. Complete development of A. thunbergii from egg to adult occurred between 20 and 30°C, while eggs did not hatch at 35°C. Immature stage development time decreased significantly with an increase in temperature, with the exception of fifth nymphal stage, duration of which was similar for all temperatures. The fecundity was maximal at 20°C with an average of 132.8 eggs per female and 1.7 egg per female per day. The gross reproductive rate (GRR) was the highest at 20°C with 75.79 daughters per female compared to 19.56 and 2.69 daughters per female at 25 and 30°C, respectively. The intrinsic rate of increase r was maximal at 20°C with 0.013 and negative at 30°C. The time required for the reared population to double (doubling time Td) was shorter at 20°C with 53.31 days compared to 115.52 days at 25°C. Our study provides basic information on A. thunbergii biology that will contribute to a better understanding of the pest distribution and dynamics on arabica coffee in East Africa.

Termites are an important component of savannah ecosystems throughout Africa. Despite their importance in the ecosystem, they can be serious pests of structures, houses, rangelands, tropical forestry, and agriculture. For many decades, chemical insecticides have remained popular for termite management worldwide. However, with the growing environmental concerns over pesticides, biological control using entomopathogenic fungi such as Metarhizium anisopliae (Metschnikoff) Sorokin has become an often-considered alternative. Metarhizium anisopliae is an ubiquitous, naturally occurring pathogen, which has been reported infecting over 200 insect species; therefore, there is concern that use of M. anisopliae may affect non-target organisms. The effects of M. anisopliae isolate ICIPE 30 were experimentally tested on the ants which associate with Odontotermes spp. termite mounds. Laboratory bioassays were carried out to assess the effects of direct exposure to M. anisopliae on Crematogaster mimosae and Camponotus spp. In addition, ant diversity was monitored over 18 months from termite mounds treated with M. anisopliae in situ near the Mpala Research Centre in Laikipia District of central Kenya. Results obtained revealed no effects of direct exposure to M. anisopliae isolate ICIPE 30 on the mortality of C. mimosae (F1 = 7.29, P = 0.0072) or Camponotus spp. (F1 = 13.01, P = 0.0004) in the laboratory. No significant difference in Shannon indices of ant diversity from treated and untreated mounds (F1 = 0.016, P = 0.8989) was found. It is evident that M. anisopliae has no negative effects on ants that are associated with Odontotermes spp. termites.

An invasive pest, Tuta absoluta (Meyrick) has been observed infesting tomato Solanum lycopersicum L. (Solanales: Solanaceae) in Central Uganda. The affected farmer made the report, and upon visiting the farm, we observed tiny larvae, green to cream in colour with a black head feeding on tomato leaves, fruit, as well as tender stems. Also, we saw several tiny moths resting on screen house linings. Delta traps baited with TUA-Optima® (Russell IPM) were set in and around the affected farm. Dozens of moths were attracted and trapped on the sticky surface of the traps. The team tentatively identified the insect as T. absoluta. Scientists at the International Centre of Insect Physiology and Ecology (icipe) in Nairobi, Kenya identified the insect using morphological features and molecular techniques.

Herbivory by insects and mites on physic nut (Jatropha curcas L.) seedlings was investigated and compared with irrigation in the semi-arid Sahelian Niger, utilizing a randomized complete block design experiment. Three water treatment protocols were applied and the types of damage were recorded. Less than 5% of the seedlings died during the 10-month trial period with sap suckers causing the most damage on the surviving plants. Plants with high production of biomass and leaf cover (foliage) were most strongly positively correlated with irrigation and were also the plants that endured the highest degree of herbivory. The low dieback may indicate that defence mechanisms counteract seedling herbivory and that drought-stressed plants invest more in their defence mechanism system than vital plants.

Aquatic larval habitat conditions influence the development, fitness and vectorial capacity of mosquitoes. In turn, human activities can influence these conditions and shape mosquito vector distribution, thus affecting pathogen circulation and transmission. We measured environmental factors (chemical and microbial) in mosquito larval habitats and evaluated their potential as predictors for the occurrence of different mosquito species in an arbovirus and malaria endemic region of western Kenya. We found significantly greater proportions of Aedes aegypti mosquito larvae in ammonium and phosphate rich habitats, suggesting that fertilizer usage could potentially increase aquatic habitat suitability and Aedes vectored disease transmission. Anopheles gambiae larval habitats correlated significantly with higher temperatures. However, none of the Culex species’ habitats correlated with investigated variables, indicating greater larval plasticity compared to Aedes or Anopheles. Profiling of bacterial communities by 16S rRNA pyrosequencing revealed Proteobacteria, Bacterioidetes and Firmicutes as the major bacteria phyla present in mosquito aquatic microhabitats. Although there were no correlations between microbiota composition or diversity and larval species abundance, the dominant genera of microbes detected in larval habitats were reported in larval and adult mid-guts, suggesting that bacteria acquired from the larval habitats are transmitted to adult stages. This study identified the chemical and bacterial composition of aquatic microhabitats that are conducive to the development of different mosquito vectors in western Kenya. This information can inform potential vector control strategies by assessing management of breeding sites based on likely exposure to fertilizer, light and bacterial fauna.