Field Populations Of Larvae Research Articles

Microbial diversity in the larval gut of field and laboratory populations of the sugarcane weevil Sphenophorus levis (Coleoptera, Curculionidae)

The sugarcane weevil, Sphenophorus levis, is a wide-spread sugarcane pest in Brazil. Sphenophorus levis may depend on microorganisms that inhabit its intestinal tract. We examined the diversity of the gut microbiota of S. levis, which was characterized using culture-dependent and culture-independent methods. Analysis of 16S rRNA amplified directly from the gut community revealed the presence of 14 genera, one group from the Candidatus category, one uncultured group assigned to the family Flavobacteriaceae, and one uncultured group assigned to the family Enterobacteriaceae; all of them are members of the Alpha-Proteobacteria, Beta-Proteobacteria, Gamma-Proteobacteria, Firmicutes, and Bacteroidetes phyla. Microorganisms isolated through culture-dependent methods were classified according to morphological parameters and by 16S rRNA gene sequences. In addition to bacteria, four filamentous fungi were isolated. A higher bacterial diversity was observed in field populations of larvae than in laboratory populations, according to the Shannon index (Field H' = 3.36; Laboratory H' = 3.26). Five genera of bacteria and two filamentous fungi were found to have cellulolytic activity. This is the first report of S. levis gut microbiota; it may contribute to development of strategies for controlling this sugarcane pest.

Larval Development and Its Photoperiodic Control in the Firefly Pyractomena lucifera (Coleoptera: Lampyridae)

The firefly Pyractomena lucifera (Melscheimer) was reared successfully under laboratory and field conditions. Larval development to the pupal stage was controlled by photoperiod: under short-day conditions development to the pupal stage was delayed, but under long-day conditions development continued without delay. This is a diapause-controlled dormancy. In laboratory-rearing experiments larvae matured in 65 (males) or 80 (females) days and consumed 15.3 (males) or 20.0 (females) snails when reared under 16:8 h light-dark conditions. Larvae matured after 175–177 d when reared under 11:13 h lightdark conditions and consumed 25 (males) or 33.2 (females) snails. In field-rearing experiments larvae reared during the summer completed development to the pupal stage within 9 wk. Field-reared larvae did not pupate after 18 September but continued to feed and grow. Large larvae field-collected between October and January appeared to be in diapause, for the time for development to pupation was longer for a group of these larvae reared under short-day conditions than for another group reared under long-day conditions. Field populations of larvae did not appear to develop as rapidly as did field-reared larvae. Some larvae from the summer brood may complete development by fall, but most of the summer brood appear to overwinter as medium or large larvae and complete development the following summer.

Control of the grass grub, Costelytra zealandica (white) (Coleoptera: Scarabaeidae), by application of the bacteria Serratia spp. causing honey disease

AbstractIsolates of Serratia marinorubra and S. liquefaciens pathogenic for Costelytra zealandica (White) were artificially cultured and applied to field populations of larvae of C. zealandica in New Zealand in the late summer and autumn of 1984. In four trials, when bacteria were applied from February to late March, high levels of disease transmission were recorded. Three months after application, significant (P<0·05) reductions of 30–59% in the larval populations were obtained, and 47% of the remaining larvae in the treated plots were diseased, suggesting the long-term effect would be greater. Treatment resulted in a 30% increase in dry matter production in the pastures. There was no consistent difference between the bacterial isolates tested. Application of the bacteria in May had no effect on the larvae, suggesting that they were no longer susceptible. It is concluded that these pathogenic isolates should be developed further as microbial insecticides for control of C. zealandica.

Microbial control of the fruit tree leafroller,Archips argyrospila [Lep.: Tortricidae] in California

Field populations of larvae of the fruit tree leafrollerArchips argyrospila (Wlk). were practically eliminated following spray application ofBacillus thuringiensis Berliner serotype III at 192 and 80×106 I.U. per litre on the host trees,Cercis occidentalis. Spray applications of lower rates ofB. thurienginsis serotype III at 18.9 and 32.1×106 I.U. per litre and mist application ofB. thuringiensis serotype 1 at 8.0 and 16.0×106 I.U. per litre gave partial control of populations ofA. argyrospila larvae. A granulosis typeBaculovirus, applied by hand sprayer at 1.4×109 granules/ml produced approximately 50% reduction of 5th instarA. argyrospila larvae onC. occidentalis trees. It was concluded thatB. thuringiensis and the granulosis typeBaculovirus are promising control agents forA. argyrospila larvae.

Studies on the life-cycles of two species of soldier flies (diptera, stratiomyidae) which affect sugar-cane in queensland

AbstractIn Queensland, adults of the soldier flies Inopus rubriceps (Macq.) and I. flavus (James) emerge between March and June, usually on still warm days. The females mate and oviposit on the day of emergence, the eggs being deposited close to the soil surface under small clods or in cracks. Incubation takes 6–13 days, depending on temperature. Observations on larvae reared on maize seedlings showed that the wide size range in field populations of larvae at all times of the year was due to the differing rates of development of larvae of one generation, to overlapping generations and to a difference in size between the sexes. One-third of the larvae matured to adults at the end of one year, but only a few of the remainder survived to emerge as adults after two years, one-year larvae having 8–9 instars, and two-year larvae having 10–12. Pupation occurred within the last larval skin, and the pupal period lasted three weeks.

LIFE HISTORY AND BIOLOGY OF THE LEAF BAGWORM, HYALARCTA HUEBNERI (WESTWOOD) (LEPIDOPTERA: PSYCHIDAE)

The endemic Australian psychid Hyalarcta huebneri commonly damages Pinus radiata growing in forestry plantations, and attacks fruit trees, ornamental trees and shrubs. It occurs in subcoastal and coastal areas from north-eastern Queensland to Western Australia, and a total of 41 host plants are recorded. It is normally univoltine with 6 larval instars; the final instar in the male does not feed. Field populations of larvae have been apportioned to instars on the basis of head size. The sex ratio approximated 2 males: 1 female. The life history stages are described, the larval heads being treated in more detail.

アカイエカ幼虫自然集団の dieldrin 抵抗性の解析

アカイエカ幼虫自然集団の dieldrin 抵抗性の解析