Behavioural and antennal responses of the sorghum chafer Pachnoda interrupta (Olivier) were tested to the synthetic compounds, such as eugenol, methyl salicylate, methyl anthranilate, isoamyl acetate and butyl butyrate. In the field, all odour-baited traps, except isoamyl acetate applied on cotton dispensers, were significantly more attractive than blank (unbaited) traps and all compounds, except isoamyl acetate, elicited dose-dependent responses in both male and female antennae. Dispenser type (cotton wick or rubber septum), trap location (inside or outside sorghum fields) and season (mating/July or feeding/September) affected the performance of the different compounds as lures. In July, methyl salicylate applied on cotton was the most attractive lure, whereas the most attractive treatments in September were eugenol and isoamyl acetate on rubber septa. Possibly due to odour and visual competition from the sorghum plants, traps placed outside the sorghum fields caught significantly more beetles than traps placed inside the fields. The trapping efficiency of a locally produced trap was found not to be competitive with that of the commercially available Japanese beetle trap. Overall, the results suggest that trapping with semiochemicals has a potential in sorghum chafer management, either for mass trapping and/or as part of an integrated pest management programme.

Female-biased sex ratios in Danaus chrysippus (Linnaeus) (family Nymphalidae, subfamily Danainae, tribe Danaini) populations are attributed to the action of an endosymbiotic ‘male-killer’ bacterium of the genus Spiroplasma. In stark contrast to the extensive geographic range of their host, the Spiroplasma appears to be restricted to East Africa, where four African D. chrysippus subspecies exist sympatrically and form a hybrid zone. In this study, specimens collected at three sample sites within the hybrid zone were screened for Spiroplasma infection. The findings demonstrate that, within the hybrid zone, the frequency of Spiroplasma infection varies both spatially and temporally. Host genotype at three biallelic wing pattern loci, representative of subspecific genetic divergence, is correlated to Spiroplasma infection. Linkage between the frequency of the recessive a allele and Spiroplasma is established, suggesting the presence of a linked allele controlling infection susceptibility. In addition, a negative correlation between D. chrysippus forewing length and Spiroplasma infection is identified, suggesting that infection has a deleterious effect on body size.

The insect fauna of rain-fed rice, Oryza sativa, was assessed using the sweep net and direct count methods. The objective of the study was to provide basic information on the insect pest complex of rice in the area and their natural enemies. One hundred and five insect species belonging to nine orders and 57 families were found. The insect orders in order of abundance were Diptera (45.67%), Coleoptera (12.77%), Lepidoptera (12.23%), Orthoptera (8.44%), Heteroptera (8.23%), Homoptera (7.03%), Hymenoptera (3.25%), Dermaptera (1.95%) and Dictyoptera (0.43%). Diopsis thoracica Westwood (Diopsidae) (69.43%) was the most abundant dipteran followed by the sarcophagids (14.93%) and calliphorids (7.11%). Members of the family Chrysomelidae represented 50% of the coleopterans followed by the coccinellids (17.46%). While 31% of the lepidopterans were noctuids, 60% were pyralids. The pentatomids (50.57%) were the most abundant heteropterans while the acridids (43%) were the most prevalent orthopterans. The homopterans were mainly Cofanaunimaculata Signoret (which represented 79%). The insects were clustered into three groups with D. thoracica alone in group 1, C. unimaculata and Sarcophaga species in group 2 and the rest in group 3. We therefore conclude that D. thoracica is the most important pest of rice in Ekpoma while C. unimaculata may also be very important, but Sarcophaga species appears to be the most important natural enemy in the system.

The reproductive behaviour of a generalist aphidophagous ladybird beetle Cheilomenes sexmaculata (Fabricius) was studied in detail. The males first mated at an age of about 2 days, while females mated at 1 day after their emergence. Mate recognition was displayed in five steps, viz. approach, watch, examine, mount and copulatory attempt. Being provided with four dummy models, the male appeared to recognize the female through visual and other possible cues, maybe chemical. The duration of mating was maximum (mean ± SE; 133.0 ± 2.8 min) when an unmated male copulated with a virgin female and minimum (95.0 ± 4.2 min) when a mated male copulated with a mated female. Mating duration seems to be influenced more by the change in male sexual status, thus revealing it to be male dominated. The maximum oviposition period (46.0 ± 1.2 days), fecundity (861.0 ± 2.2) and hatching percentage (64.0 ± 0.6) in C. sexmaculata were noticed after multiple matings, while these parameters were minimum (15.0 ± 1.0, 70.0 ± 2.8 and 37.0 ± 1.0, respectively) after single mating. Thus, multiple matings enhanced the total egg output and percentage of hatchability.

Cocoa (Theobroma cacao L.) is an important foreign exchange earner for Ghana. However, production is constrained by a high incidence of pests and diseases. Based on farmers' needs, this study focused on the control of capsids, mainly Sahlbergella singularis Haglund and Distantiella theobroma (Distant) (both Hemiptera: Miridae). Annual crop loss caused by capsids is estimated at 25–30%. To control capsids, formal research recommends application of synthetic insecticides four times between August and December. However, farmers hardly adopt this recommendation, which they consider unsuitable for their conditions and context. Three alternative control methods were tested with farmers: mass trapping, using sex pheromones; applying crude aqueous neem Azadirachta indica A. Juss. (Meliaceae) seed extract (ANSE) and using the predatory ant Oecophylla longinoda Latreille (Hymenoptera: Formicidae) as a biological control agent. Contrary to most previous reports, studies on temporal distribution of cocoa capsids indicated that the population peaked in March. ANSE was effective against capsids and other cocoa insect pests and did not affect the predatory ant. When O. longinoda occurred in high numbers, capsid incidence was low. Shade did not influence ant or capsid abundance significantly. ANSE caused 100% mortality of capsids in cage and 79–88% in field experiments. The sex pheromone was as effective as ANSE or ants in suppressing capsids. All the three methods were effective and compatible; hence, they can be used in an integrated pest management strategy for cocoa, including organic production in Ghana.

Information on termite assemblage in a young eucalypt plantation in Kerala was generated by running a single line transect and monthly sampling for 1 year. Through the transect sampling, 11 species were recorded under two families and four subfamilies. The subfamily Macrotermitinae dominated with eight species while the other three subfamilies were represented by a single species each. A temporal pattern of abundance was observed for the different active foraging species of termites in the monthly sampling. During April–November, a single species, Odontotermes obesus (Rambur), was the most abundant. During December–January, Microcerotermes fletcheri Holmgren & Holmgren was dominant, while Odontotermes feae (Wasmann) dominated during February and March. Rainfall was found to have a negative influence on the diversity of the active/foraging species of termites. Among the 14 species of termites collected, only four were found attacking eucalypt seedlings. Of the total termite samples collected, 40% belonged to the single species O. obesus, which was the major pest species representing 12 out of the 18 recorded incidences of termites feeding on roots of eucalypt seedlings. Among the species recorded, one was a new species and two were new records for Kerala State. The large number of non-pest species of termites indicates the beneficial role of these termites as efficient decomposers.

The biology of Neoseiulus barkeri (Hughes), Typhlodromus balanites El-Badry and Amblyseius zaheri Yousef & El-Borolossy was studied using Ephestia kuehniella Zeller eggs as food source. For N. barkeri, the development was faster and reproduction was higher than for A. zaheri. Survival of immatures of T. balanites was low on eggs of E. kuehniella and all failed to develop to adulthood. A total of 50.4 and 41.0 eggs per female were obtained when N. barkeri and A. zaheri were fed on moth eggs, respectively. A diet of E. kuehniella eggs provided the highest female longevity and mean total fecundity, which resulted in the highest net reproductive rate (Ro = 32.88), intrinsic rate of natural increase (rm = 0.139) and finite rate of increase (λ = 1.149) for N. barkeri. The mean generation time ranged between 24.65 and 25.03 days for A. zaheri and N. barkeri, respectively. The sex ratio of the progeny was strongly female biased (female/total = 0.69 and 0.58) when eggs of E. kuehniella were provided for N. barkeri and A. zaheri.

The effects of pH, sunlight and rearing temperature on infectivity of nucleopolyhedrovirus (SpltNPV) were investigated against larvae of Spodoptera litura (Fabricius). The infectivity of virus increased with increased larval rearing temperature. The LT50 values were significantly reduced from 24 to 6 days when rearing temperature was increased from 20 to 35 °C. The pH of the substrate significantly affected the infectivity of the virus. The LT50 values increased to about fourfold when the pH of suspension was raised from 7 to 11. Infectivity of the virus was more adversely affected in alkaline than in acidic suspension. Sunlight also deleteriously affected infectivity of the virus. The LT50 values increased with the increase in the period of sunlight exposure. A complete viral inactivation occurred after 12 h of direct sunlight exposure.

The stored grain weevil, Sitophilus oryzae (Linnaeus), causes significant losses to maize grains in tropical countries. Despite the nutritional superiority of the quality protein maize (QPM), an important concern is the possible vulnerability of QPM genotypes to stored grain weevil infestation. In the present study, the responses of 24 QPM inbred lines, along with several non-QPM inbred lines and hybrids, were evaluated against S. oryzae under laboratory conditions. Two attributes, namely (i) % weight loss in the grains after a fixed period of incubation with the insect and (ii) the number of progeny insects (insect multiplication) generated from six pairs of adult insects, were considered. A cumulative resistance index was computed for each genotype giving equal weight to both attributes. The study revealed DMRQPM-60 and CML167 as the most resistant entries. Shaktiman-1, the released QPM hybrid in India, showed moderate resistance against the grain weevil. However, most of the elite QPM inbred lines as well as some non-QPM inbred lines and hybrids were found to be highly susceptible to the weevil infestation. To explore the possible relationship between enhanced protein quality and varying degree of kernel vitreousness and vulnerability to the grain weevil infestation, both the QPM and the non-QPM genotypes were analysed. The correlations between kernel quality traits and kernel texture with % kernel weight loss due to weevil infestation and insect multiplication were found to be non-significant, indicating possible influence of other factors, including pericarp thickness and endosperm composition, in determining the susceptibility of the QPM genotypes to S. oryzae. The study indicates that QPM genotypes are not necessarily susceptible to the stored grain weevil and identifies promising QPM genotypes with resistance to S. oryzae.