The presence of ecdysteroids during the larval life cycle and in the abdomens and ovaries of pregnant tsetse flies was established using radioimmunoassay. The hormone titre rises on day 9 of the larval life cycle 2–3 days after the hardening of the polypneustic lobes, mouthparts, phragma and anus. How initiation of tanning of the cuticle of the polypneustic lobes and later the puparium of tsetse fly is regulated is discussed as these events are separated in time by several days. It would seem to be unlikely that the pyrokinin neuropeptide, which is responsible for initiating the events that lead up to pupariation, is also involved 2–3 days earlier in the life cycle. The objective was to ascertain whether 14C-l-p-tyrosine enters the lobe cuticle in vivo and in vitro much faster than into integument cuticle on the 7th day of the pregnancy cycle. The result showed that the uptake of tyrosine into the lobes was 11–12 times faster than into the rest of the cuticle. Some evidence is presented that haemocytes underlying the epidermis are involved in overcoming the barrier to uptake of the phenolic compounds required for sclerotization of the lobes. Pupariation could be retarded by physical means such as ligaturing of the larvae. To try to break this inhibition (retardation) of pupariation in ligatured larvae, 14C-l-p-tyrosine metabolites were injected, with and without ecdysteroids, into the anterior of ligated larvae. The result of this experiment showed that the steroid hormone did not overcome the inhibition but neither does injecting tyrosine, dihydroxyphenylalanine, dopamine or tyramine. Evidence obtained from chromatography and electrophoresis indicated that N-acetylation of dopamine did not occur in the haemolymph of larvae that were artificially retarded. This impact raises the possibility that N-acetyltransferase and acetyl-coenzyme A could be released in pre-pupae after the action of a neuropeptide breaks the retardation of tanning.

Field and laboratory observations were carried out to understand the significance of prolonged copulation and the male substance transferred from males to females in the white grub beetle Dasylepida ishigakiensis Niijima & Kinoshita. Adults emerged from the soil in the evening and formed mating pairs on sugarcane plants, where copulation lasted for 1–3 h. Mating pairs (30%) observed in the field were accompanied by one or two additional males. Some females mated with one such male after ending copulation with the first male, showing multiple mating. After mating, males dropped to the ground to burrow into the soil earlier than females. Females received a large amount of colloidal secretion from males during mating. The amount and rate of transfer of this secretion from males to females were investigated in this study. Transfer of the secretion from males to females was completed within 30 min, and females that had mated with two males in the laboratory stored a larger amount of male secretion in the bursa copulatrix than those that had mated once. The results of both field and laboratory observations might indicate a possibility that prolonged copulation serves as a post-insemination female guarding behaviour to prevent mating by other conspecific males.

The tea mosquito bug Helopeltis theivora (Waterhouse) is an important economic pest of tea in India. The development of resistance in H. theivora populations obtained from a conventional plantation and an organic plantation was studied in the laboratory for five generations, and associated changes in life cycle traits were assessed. Selection using sub-lethal concentrations of endosulphan resulted in a 4.4-fold increase in insecticide resistance ratio from the F1 to the F5 generation in the H. theivora population from the conventional plantation. By the F5 generation, nymphal duration was higher and fecundity was lower in the endosulphan-selected strain than in the non-selected strain from a conventional plantation and the susceptible strain from an organic plantation. These findings have practical implications for insecticide resistance management of this important sucking pest of tea.

We investigated the role of an entomogenic gut bacterium Pseudomonas fluorescens on larval development and survival of Culex vishnui Theobald, the mosquito vector of Japanese encephalitis, which breeds exclusively in rice field water in tropical regions. The bacterium could be isolated from the midguts of third and fourth instars of the mosquito. Pseudomonas fluorescens strain 1 (Ps1) was identified as the one vital to C. vishnui larval survival. The phenotypic characteristics of this strain are described. As part of the study, antibiotics were used to cure C. vishnui larvae of Ps1; thus cured larvae did not survive when subsequently reared in sterile or antibiotic-treated rice field water or tap water. In contrast, 93.3–100% of cured larvae developed into normal adults when subsequently reared either in unsterile or in sterile rice field water or in tap water containing Ps1 bacteria (5 × 103 ml). Thus the elimination of Ps1 from breeding water could be used as a strategy to suppress the mosquito growth, as part of an innovative approach to control Japanese encephalitis.

The age-specific mating incidence and mating behaviour of an aphidophagous ladybird beetle Coelophora saucia Mulsant were studied. Males started mating at the age of 4 days. Newly emerged females mated with older males albeit forcibly. The incidence of mating was 100% at the age of 10 days. Courtship involved five steps, viz. approach, watch, examine, mount and attempt, and was male dominated under laboratory conditions. Results indicate that physical cues probably play a role in the initiation of courtship, while chemical signals are probably involved in the continuation of courtship, culminating in intromission. The mating duration, latent period and number of bouts gradually decreased with increase in the number of matings; however, the interval between bouts slightly increased. Pseudo-mating with dead mates was observed in C. saucia. The oviposition period, fecundity and % egg viability were highest in females mated multiple times, while lowest in those that mated once.

In recent years, the serpentine leaf miner Liriomyza trifolii (Burgess) has become a major pest of cotton (Gossypium spp.) in India, with high levels of incidence observed at the seedling stage, particularly in transgenic Bt cotton. We monitored the severity of infestation and damage by L. trifolii to transgenic and non-transgenic genotypes of Gossypium arboreum L. and G. hirsutum L. between 2002 and 2007. Overall, significantly lower L. trifolii damage occurred in G. arboreum varieties than in G. hirsutum varieties and hybrids. Among the G. hirsutum genotypes, damage was significantly lower in varieties than in hybrids. However, no significant differences in damage were observed between Bt and non-Bt cotton hybrids. Abiotic factors had a major influence on the severity of damage; there was a significant and negative association of L. trifolii damage with open pan evaporation (E), maximum temperature, solar radiation and sunshine, and a significant and positive association with relative humidity and rainfall (RF). Multiple stepwise regression analysis indicated that 99% of the variation in L. trifolii damage was accounted for by RF, open pan E and relative humidity.

Exploratory field surveys of the natural enemies associated with balloon vine Cardiospermum grandiflorum Swartz, an environmental weed in South Africa, Australia and other countries, were conducted in northern Argentina from 2005 to 2009. The surveys included other plant species in the genus Cardiospermum and other native Sapindaceae, permitting an assessment of the distribution and host range of the natural enemies. Seventeen phytophagous insects in five orders and ten families, and two fungal pathogens were found. The nature of the potential agents' damage, their field distribution and abundance, and the results of preliminary host-specificity testing indicated that the seed-feeding weevil Cissoanthonomus tuberculipennis (Coleoptera: Curculionidae) and the fruit-galling midge Contarinia sp. (Diptera: Cecidomyiidae) were the most promising biological control agents for C. grandiflorum outside of its native range.

Host plant resistance is an important tool in the management of the banana weevil Cosmopolites sordidus (Germar). Although ovipositing females do not discriminate between resistant and susceptible cultivars, plants of resistant cultivars have smaller larval populations and sustain less damage in the field. These observations suggest that lower damage levels observed in resistant cultivars reflect larval success. This study was carried out to evaluate laboratory screening of banana cultivars as a rapid screening method for resistance to the banana weevil by determining the influence of cultivars on weevil survivorship, development duration and adult weight. Larvae were raised on corm pieces of two susceptible, three intermediate and four resistant cultivars, resistance categories having been determined from a previous field screening trial. The developmental period was prolonged in resistant cultivars. However, cultivars had less influence on survivorship and adult weight. Moreover, the ranking of survivorship did not correlate with resistance levels observed in the field. The implications of these findings for laboratory screening of cultivars for resistance to C. sordidus are highlighted.

Use of host plant resistance for the management of the banana weevil Cosmopolites sordidus (Germar) requires development of rapid cultivar screening methods. A previous study showed prolonged development of larvae feeding on excised plant material of resistant cultivars and suggested partial breakdown of resistance in such plant material. In the current study, development and survivorship of larvae feeding on potted plants of banana cultivars with differing levels of resistance were evaluated. Weevil performance was evaluated on one susceptible (Atwalira), one intermediate (Kabula) and four resistant cultivars (FHIA 17, Kayinja, Kisubi and Yangambi Km5). Differences in development of larvae feeding on the susceptible Atwalira and intermediate/resistant cultivars became apparent at 15 days after infestation of plants. Differences in survivorship of larvae feeding on different cultivars were not statistically significant. Results of this study show that experiments using potted plants can be used to screen for resistance to banana weevil based on the development of larvae. The influence of previous feeding damage to banana plants on larval development and survivorship in a susceptible (Atwalira), an intermediate (Kabula) and a resistant cultivar (Kisubi) was also examined. While no effects on larval development rate were apparent, survivorship was reduced in previously attacked plants for the intermediate cultivar, indicating that resistance may be induced by previous weevil attack of plants.

In West Africa, Callosobruchus maculatus Fabricius mainly develops on cowpea (Vigna unguiculata (L.) Walpers) and sometimes on Bambara groundnut (Vigna subterranea (L.) Verdcourt). A survey on the development of a C. maculatus strain selected on cowpea was undertaken during eight generations on two local varieties of Bambara to determine their level of acceptability and suitability for the pest and its evolution over time and successive generations. When C. maculatus females were in contact with seeds from both Bambara varieties for the first time, they laid fewer eggs on these hosts in comparison with cowpea. However, females that have developed inside Bambara cv. Local Beige seeds deposited more eggs on their hosts of origin from the first generation onwards. The same result was obtained on Bambara cv. Local Striped seeds from the F4 generation onwards. Egg viability was not affected by host variability. On the contrary, the larval survival was significantly reduced on Bambara seeds. Larval survival and intrinsic rates of natural increase were improved on both Bambara varieties with successive generations in comparison to cowpea. Our results demonstrate that in a non-choice situation, C. maculatus is able to develop on both Bambara cv. and even increase its reproduction potential over successive generations, regardless of the climatic variations. The results help to better understand why C. maculatus is becoming a serious concern on Bambara in West Africa where the pest is frequently in contact with this occasional host.

Coconut is one of the major crops of commercial importance among the palms. The leaf-eating caterpillar Opisina arenosella Walker is the most important lepidopteran pest of coconut palm in India and Sri Lanka. Assessment of crop loss is essential for a realistic planning for research and developmental policies. Information on the yield loss in coconut due to O. arenosella attack is very meagre. In the present study, results of investigations carried out on leaf-eating caterpillar-induced yield loss in coconut palms in Kerala, India, for a period of 4 years (2002–2005) are presented. A maximum crop loss of 45.4% in terms of nut yield was recorded from infested palms in the succeeding year of severe pest incidence. The infested palms also showed reduction in bunch and leaf production to the tune of 21.0 and 13.8%, respectively. The pest-attacked palms regained their normal yield potential by the fourth year after heavy pest infestation.

In a bid to develop technologies that serve grower needs for economic management of pests and diseases of hot pepper (scotch bonnet) while protecting public health and the environment, a study to assess the potential of cover cropping and/or less-risk pesticide usage in the management of pests and diseases of hot pepper was conducted for two consecutive seasons in Uganda. A split-plot randomized complete block design with three replications was used with cropping system (main plots) and pesticide treatment (sub-plots) as the factors. There were two cropping systems: the hot pepper+cowpea system vs. a hot pepper monocrop and five pesticide treatment options: (i) prophylactic treatment of plots at transplanting with granular carbofuran; (ii) weekly sprays of a neem-based formulation; (iii) combination of the prophylactic carbofuran treatment and neem; (iv) sulphur sprays at 10-day intervals (season 2 only); and (v) the untreated control. Data were collected on population dynamics of aphids, whiteflies, thrips, mites, nematodes and on plant performance parameters of branching and fruit weight. Results indicated that the hot pepper+cowpea system greatly lowered infestations of aphids and nematodes on hot pepper, but did not decrease thrips and whiteflies; and brought about a yield penalty on hot pepper. Prophylactic applications of carbofuran and/or sprays of a neem-based formulation lowered populations of aphids and whiteflies on hot pepper to varying extents; and increased yield of pepper.

Resistance mechanisms to the pod-sucking bug (PSB) Clavigralla tomentosicollis Stäl, in cowpea genotype IT86D-716, were studied in field and laboratory. Non-preference was evaluated on three cowpea varieties (IT86D-716, Moussa local and KVx396-4-5-2D) through measuring differences in population parameters and extent of damage under field and laboratory conditions. Antibiosis was evaluated based on development parameters of C. tomentosicollis when reared on pods of the aforementioned varieties. The variety IT86D-716 consistently exhibited both non-preference and antibiosis resistance mechanisms to C. tomentosicollis. A chemical analysis of the pods was conducted to identify compounds conferring antibiosis. Several compounds including cyanogenic heterosides, flavonoids, tannins and trypsin inhibitors were present in pods of IT86D-716. Evidence suggests that antibiosis due to these compounds may contribute to the resistance to PSB. In the case of antibiosis, 5-day long exposures were adequate to observe nymphal mortality. Based on this finding, a fast, reliable and low-cost screening of pods can be carried out in the laboratory for identification of lines that are C. tomentosicollis resistant.

The use of synthetic pesticides among vegetable producers in urban and peri-urban Cotonou, Benin, has been increasing to the extent that certain insect pests have developed resistance to the pesticides. This paper assesses the impact of the farmer field school approach in an integrated pest management (IPM) project that aimed to increase IPM knowledge, adaptation/adoption of IPM options, and appropriate application of pesticides and awareness of related health hazards among vegetable producers in Cotonou. A sample of 54 semi-structured interviews was conducted with the vegetable producers, and a double difference model was used to compare the knowledge and practices before and after the project. The project led to increased knowledge about IPM, which was to some extent adapted into the participants' production systems, although no significant difference was noted for the type of synthetic pesticides used. The producers do adapt their practices when new technologies and practices emerge, but not always in ways that are environmentally sound or healthy.

We report here the pathological effects of a microsporidian isolate (Nosema sp.) from the lepidopteran teak defoliator Hyblaea puera Cramer. The spores were ovo-cylindrical and had a mean size of 5.1 × 2.8 μm. The midgut and fat body were the primary organs infected by the microsporidium. Subsequently, infection was observed in Malphigian tubules, tracheal epithelium and gonads. The sequence of infection observed was: midgut – fat body – tracheal membrane – Malpighian tubule – gonad. Infection of this microsporidium produced a marked negative effect on the growth and development of larvae. The weight of healthy larvae increased about 22 times from the 3rd instar to pupation while the increase was about 12 times in the infected larvae. Rearing experiments conducted in the laboratory revealed a high potential for horizontal transmission (>90%) of the microsporidium among the defoliator larvae developing together. A nearly equal degree of vertical transmission (88.7%) was also observed from the infected females to the progeny larvae. The observations reported here indicate the prospect of the microsporidium as a bio-control agent against the defoliator pest if exploited properly. Small subunit rRNA gene sequence analysis revealed that this microsporidium differed from Nosema bombycis of silk moth by only two nucleotides. The teak moth and the silk moth are not as closely related as these two parasites appear to be, implying the likelihood of host switching.

The life cycle of the koinobiont endoparasitoid Platygaster diplosisae Risbec was investigated to assess its suitability as a biological control agent of the African rice gall midge Orseolia oryzivora Harris & Gagné. Screen house and laboratory experiments were conducted in 2008 under ambient conditions in Ibadan, Nigeria. Morphological characteristics of the parasitoid's immature stages were observed, and its life cycle parameters were measured. The parasitoid's average egg incubation period was 12.9 days, and on average, 67.3% of eggs hatched. Three instars occurred, with average developmental durations of 2.2, 0.5 and 2.5 days for the 1st, 2nd and 3rd instars, respectively. Pupal development took 6.7 days until adult emergence. Pre-oviposition period averaged 12.1 h, and a female laid on average 95.2 eggs, with a mean oviposition period of 3.5 days. The longevity of males and females was 3.0 and 4.1 days, respectively, without food; longevity was extended when honey and water were provided. Mating and oviposition behaviours were recorded, and a sex ratio of eight females to one male was found in parasitoid progeny. The parasitoid had a total developmental period of 27.3 days, which is about 5 days longer than that of its host. In conclusion, P. diplosisae can play an important role in the biological control of O. oryzivora on rice, and should be conserved in African rice production systems.

A decision-making sampling plan was developed to initiate new and validate ongoing area-wide red palm weevil Rhynchophorus ferrugineus (Olivier) integrated pest management (IPM) programmes in date palm plantations of Saudi Arabia based on the concept of sequential sampling. Spatial distribution studies revealed that R. ferrugineus population was aggregated and followed the negative binomial series with a mean aggregation index (common K) value of 3.56. In the sampling plan developed, young date palms are inspected in a sequence in units of 100 palms (1 ha) until an accurate decision on the infestation level can be made. The plan rates infestations as low and high if d0 ≤ 0.478n − 7.519 and d1 ≥ 0.478n+7.519, respectively, where d0 and d1 are the cumulative maximum and minimum infested palms per ha (100 young palms) for not recommending and recommending area-wide management of R. ferrugineus, respectively, and n is the area sampled in ha. In this sampling plan, if 100 palms are inspected and eight or more infestations are detected, then area-wide R. ferrugineus IPM is required. On a 100 ha scale (10,000 palms) the plan becomes stricter and permits only 55 infestations.

The biology of the African rice gall midge Orseolia oryzivora Harris and Gagné was investigated in screenhouse and laboratory studies, and its incidence on cultivated wet-season rice was studied in farmers' fields during the 2006 and 2007 rice-growing seasons at two localities in Nigeria. This insect is nocturnal, and mating takes place immediately after emergence. Both mated and unmated females lay eggs, with mated females laying on average 389 eggs each, and unmated females laying about 87 sterile eggs. The egg stage takes on average 2.5 days. Larval development takes 3.6, 3.3 and 3.0 days for the first, second and third instars, respectively, while the pre-pupal and pupal stages take 2.8 and 6.1 days, respectively. Adult females live for 48–78 h, while males live for 24–30 h. The life cycle of O. oryzivora is completed within 21–24 days under screenhouse conditions. The adult male is slender and about 3 mm long, while the female is more rounded with a 4 mm long body and a bright red abdomen. The insect produces unisexual progeny. Field incidence is low at the beginning of the rainy season, peaking with the peak in rainfall and humidity that concurs with the vegetative stage of the crop. The population of the midge declines as temperatures rise. In conclusion, prediction models may be developed based on weather parameters, to aid in forecasting the field incidence of O. oryzivora and its management strategies. Furthermore, it may be possible to reduce the damage caused by O. oryzivora to rice crops by altering planting period and taking into account environmental factors.

Protease inhibitors (PIs) retard growth and development and cause mortality in a range of insect pests belonging to various orders. Some transgenic plants expressing PI genes have also been effective against insect pest attack. The effects of two purified soybean PIs, i.e. trypsin inhibitor (Kunitz type; SBTI) and trypsin–chymotrypsin inhibitor (Bowman-Birk type; SBBI), were investigated on first and third instar larvae of the melon fruit fly Bactrocera cucurbitae (Coquillett) in laboratory feeding bioassays. The larval period of both the first and third instar larvae was prolonged when the larvae were treated with various concentrations of SBTI and SBBI. The total development period prolonged significantly in both the instars of larvae treated with SBTI, but in SBBI-treated larvae, the development period was delayed significantly only in the third instar larvae. A decrease in percentage pupation and adult emergence was observed in the first and third instar larvae treated with different concentrations of both SBTI and SBBI. The present studies showed that SBTI and SBBI have a potential in inhibiting the growth and development of melon fruit fly, but further detailed and molecular level studies are required before their use in transgenics.