Bacillus thuringiensis serovar israelensis is highly toxic to the coffee berry borer, Hypothenemus hampei Ferr. (Coleoptera: Scolytidae)

A native collection of Bacillus thuringiensis strains was screened, once a reliable bioassay technique to assess the toxicity against the coffee berry borer (CBB) first-instar larvae was developed. A first round of bioassays with 170 strains indicated that the great majority of them showed no or very little insecticidal activity and that very few showed significant levels of toxicity. Interestingly, only those strains that had previously been associated with mosquitocidal activity were also toxic to CBB. Qualitative bioassays (using one high dose) were carried out only with those native mosquitocidal strains, corroborating their significant toxicity towards the CBB first-instar larvae. Most of these strains belong to serovar israelensis. In a second approach, strains from the Institut Pasteur type collection, whose mosquitocidal activity had been previously demonstrated, were also subjected to bioassays. Only those strains that showed a comparable protein content in their parasporal crystals to the israelensis type strain also showed high levels of toxicity towards CBB. Finally, an accurate LC(50) was estimated, using purified parasporal crystals from B. thuringiensis serovar israelensis type strain, at 219.5 ng cm(-2) of diet. All the statistical requirements for a reliable estimator were fulfilled. This is the first report of B. thuringiensis serovar israelensis being active against a coleopteran species.     

Abiotic mortality factors of the coffee berry borer (Hypothenemus hampei)

Mortality of the coffee berry borer was studied under controlled laboratory conditions in Tapachula, Mexico. For adult female borers subjected to a range of relative humidities (RH) without food at 25°C, the longest mean survival time (20 days) was obtained at 93.5% RH. Adult borer survival was also studied at a range of temperatures for a fixed relative humidity (93.5% RH); at 20°C mean survival time was 28 days. Fecundity and mortality of borer stages in berries was studied for a range of humidities at 25°C. Maximum fecundity was obtained at 90 and 93.5% RH. Immature stages were ejected from the berry at 84% RH and above, which is interpreted as a form of brood hygiene.     

Alternative Hosts for Bethylid Parasitoids of the Coffee Berry Borer, Hypothenemus hampei (Coleoptera: Scolytidae)

Three species of bethylid wasps, Prorops nasuta Waterston, Cephalonomia stephanoderis Betrem, and C. hyalinipennis Ashmead, attack the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae), by both predation and parasitism. C. hyalinipennis has only recently been reported to attack H. hampei. Its previously recorded hosts belong to the coleopteran families Curculionidae, Anobiidae, and Scolytidae. We evaluated five further coleopteran species, in the families Curculionidae, Bostrichidae, and Bruchidae, as alternative hosts. High proportions of all five species were both fed upon and oviposited on (normally by concurrent host feeding). Offspring developmental mortality varied greatly (12–95%) on different host species. Offspring production per host was about three times greater than on H. hampei when females were presented with the curculionids Caulophilus oryzae (Gyllenhal) and two species of Sitophilus. C. stephanoderis and P. nasuta are currently the main biological control agents of H. hampei: they have long been thought to be monophagous but C. stephanoderis has recently been reported to attack H. obscurus. We evaluated C. oryzae, as a potential host or prey for P. nasuta, and both C. oryzae and Sitophilus sp. for C. stephanoderis. Host feeding was very common in both parasitoid species. The majority of females also oviposited on C. oryzae (71% P. nasuta, 60% C. stephanoderis) and 20% of C. stephanoderis parasitized Sitophilus sp. Fifty-two percent of C. stephanoderis and 7% of P. nasuta offspring survived to adulthood when developing on C. oryzae. The lifetime fecundities of these parasitoids presented with these host species were, however, low (maximum 17 eggs, mean ≤ 8.25) and preoviposition periods were generally long (ca. 19 days). Adult female C. stephanoderis lived longer when presented C. oryzae rather than Sitophilus sp. Host feeding also increased longevity. We discuss these results in the context of mass rearing these bethylids for release as biological control agents.     

Isolation,morphological and molecular characterization of Bacillus thuringiensis strains against Hypothenemus hampei Ferrari (Coleoptera: Curculionidae: Scolytinae)

The coffee berry borer Hypothenemus hampei Ferrari, 1876 (Coleoptera: Curculionidae: Scolytinae) is considered the most serious pest of the coffee crop and is controlled primarily with the use of chemical insecticides. An alternative to this control method is the use of the entomopathogenic bacterium, Bacillus thuringiensis Berliner, 1911. Therefore, the objective of this work was to select strains of B. thuringiensis virulent against H. hampei and characterize them by morphological and molecular methods to identify possible genes for the production of genetically modified plants. To achieve this objective, 34 strains of B. thuringiensis underwent a selective bioassay to evaluate their toxicity to H. hampei first-instar larvae. Among the strains tested, 11 and the standard B. thuringiensis subspecies israelensis (IPS-82) caused mortality above 90%. Then, the median lethal concentration (LC₅₀) was estimated for these strains followed by characterization using morphological, biochemical and molecular methods. The lowest LC₅₀ was obtained for strain BR58, although this concentration did not differ significantly from that of the standard strain IPS-82 or from that of strains BR137, BR80 and BR67. The molecular characterization detected cry4A, cry4B, cry10, cry11 and cyt1 genes in 10 of the most virulent strains (BR58, BR137, BR80, BR81, BR147, BR135, BR146, BR138, BR139, BR140). Strain BR67 differed completely from the others and amplified only the cry3 gene. This strain was more virulent than BR135, BR146, BR138, BR139 and BR140, but it did not differ from BR58, BR137, BR80, BR81 and BR147. The protein profile revealed proteins of 28, 65, 70 and 130 kDa, and the morphological analysis identified spherical crystalline inclusions in all strains. The results showed that the 11 strains studied have potential for use as a gene source for insertion into coffee plants for the control H. hampei, especially the cry3, cry4A, cry4B, cry10, cry11 and cyt1 genes, that were repeated in the most virulent isolates.     

Aphanogmus sp. (Hymenoptera: Ceraphronidae): a hyperparasitoid of the coffee berry borer parasitoid Prorops nasuta (Hymenoptera: Bethylidae) in Kenya

This is the first report of a hyperparasitoid of Prorops nasuta, a primary parasitoid of the coffee berry borer. Aphanogmus sp. is a gregarious ectoparasitoid of larval and pupal stages of P. nasuta, which was found in coffee berry samples collected on the ground of an organic coffee plantation in Western Kenya. The hyperparasitoid shows a clear pattern of emergence from year to year, following its host. Aphanogmus sp. parasitizes around 10% of P. nasuta immature stages under field conditions.     

Altitude and coffee production systems influence extent of infestation and bean damage by the coffee berry borer

The coffee berry borer (CBB), Hypothenemus hampei Ferrari (Coleoptera: Curculionidae: Scolytinae), is one of the major insect pests of coffee worldwide. The present study was designed to assess the level of infestation of coffee berries at different developmental stages across different altitudes and coffee management systems. The experiment was carried out at three locations in southwestern Ethiopia under two coffee management systems and four coffee berry development stages with three replications. Results of the study showed significantly highest proportion of damaged berries (37.5%), number of holes per berry (10.88) and number of adult CBB per berry (7.55) on dried leftover berries at low-altitude study sites. On the other hand, the lowest mean percent damaged berries, number of holes per berry and number of adults were recorded at mid- and high-altitude study sites. The study also showed that, CBB caused significantly highest damage in plantation coffee management system than garden coffee. Results of this study highlight proper harvesting at red ripe stage in order to minimise incidence of CBB. It is also important to design integrated management strategies to mitigate CBB damage especially in lowland plantation coffee production systems.     

几种杀虫剂对热带雨林生态区红火蚁蚁巢和工蚁的灭杀效果

为筛选出适用于云南热带雨林生态区的红火蚁Solenopsis invicta Buren防治药剂,通过7种杀虫剂对红火蚁蚁巢田间灭除效果试验测定。结果表明,20%多杀霉素悬浮剂（SC）、30%螺虫·噻虫嗪悬浮剂（SC）、70%吡虫啉可湿性粉剂（WP）、10%溴虫氟苯双酰胺悬浮剂（SC）和1%联苯·噻虫嗪颗粒剂（GR）对红火蚁蚁巢处理效果较好,药后1 d和10 d虫口减退率分别在95%和90%以上。其中10%溴虫氟苯双酰胺SC和1%联苯·噻虫嗪GR可作为红火蚁巢点处置的首选药剂;0.05%茚虫威饵剂（EB）速效性差,但药后10 d虫口减退率上升到86.8%。1.8%阿维菌素乳油（EC）药后1 d和10 d虫口减退率分别为89.3%和81%。这2种药剂可与前5种药剂交替使用。     

红火蚁的危害及其防治

一种非常危险的入侵性害虫——红火蚁近年在我国台湾和香港登陆,对中国大陆和亚洲其他地区构成严重威胁。本文介绍了红火蚁的危害以及对红火蚁的防治方法。     

Influence of host density on the reproductive strategy of Cephalonomia stephanoderis, a parasitoid of the coffee berry borer

The effect of the density of the coffee berry borer, Hypothenemus hampei (Coleoptera: Scolytidae) on reproductive and host-feeding behaviours of the parasitoid Cephalonomia stephanoderis (Hymenoptera: Bethylidae) was evaluated under laboratory conditions. The number of hosts used for oviposition was density-dependent at low host density. Beyond a density of six hosts/day, the oviposition rate reached a maximum of 1.2 eggs/day due to egg limitation. Cephalonomia stephanoderis females responded to increasing host availability with a linear increase in host feeding. Overall, parasitoids killed more coffee berry borers by feeding and paralysis than by parasitism. At low host density, the pre-oviposition phase was extended, oogenesis was delayed, more males were produced, and host feeding occasionally occurred concurrently with oviposition. We suggest that the efficacy of C. stephanoderis as a biological control agent depends on seasonal variations in host density. Inoculative vs inundative releases in coffee plantations are discussed in relation to the abundance of the coffee berry borer during the fructification and interharvest periods.     

Isolation, characterization, and molecular identification of bacteria from the red imported fire ant (Solenopsis invicta) midgut

Bacteria were isolated and cultured from the red imported fire ant (Solenopsis invicta) midgut. The small-subunit ribosomal RNA gene, (16s rRNA gene, approximately 1500 bp) was amplified from bacterial genomic DNA using the polymerase chain reaction and consensus sequence primers. Restriction fragment length polymorphism analysis revealed 10 unique profiles, indicating that at least 10 different bacteria are present in red imported fire ant midguts. The 16s rRNA gene sequence was determined for these isolates and queried against the NCBI genetic database. The results identified all isolates to at least the genus level. Antibiotic resistance profiles and biochemical activities were also determined for these species. This work provides the basis for a wider characterization of bacterial distributions in fire ant colonies and provides strains suitable for genetic manipulation to develop novel methods of fire ant control.